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gary350
04-02-2011, 11:30 PM
There is NO activity on the GMC Yukon Chevy Tahoe forum. I signed up months ago and there has been no replies and no new threads in months.

I use to own a 1997 GMC Yukon I ordered it from the factory with a fuel economy chip. It was getting 18.5 mpg in town and 24 on the highway when I sold it with 200,000. miles on it.

Now I own a 1999 Chevy Tahoe. This is identical to the GMC Yukon only difference is I get poor gas mileage it probably has NO fuel economy chip. I bought it used with 95,000. miles on it. It was getting about 17 to 18 mph when I first bought it then the mpg went down down down. The service engine light came on and Auto Zone pulled code on the computer and it said I have an air leak.

Gas mileage was down to 9 mph. A new gas cap bought the gas mileage up to 11 mph. I disconnected the battery cable over night and put it on again next morning and the service engine light went off. The heater has not getting very hot in the winter and the thermostate guage reads 120 degrees. I replaced the old thermostate with a new 195 degree thermostate and gas mileage came up to 14 mpg the dash guage was reading 140 degrees. Next I replaced the temperature sensor that tells the computer how hot the engine is the dash guage now reads 160 degrees and gas mileage came up to 15.1 mpg in town and 17.2 on the highway. Next I put in a new high CFM air filter no change in the mpg. New sparks plugs did not change MPG either. The engine now has 108,000. miles on it.

Engine back fires when I start it. I park in the garage all night next morning it back fires. I stop at the grocery store or a restaurant for 45 minutes engine back fires when I start it. Back fire is small now but in colder weather the back fire was louder.

What else can I do to get my mpg up much higher???

I would love to have 24 mph like the GMC had.

Ken_Shea
04-02-2011, 11:38 PM
You checked all the vacuum lines, especially to the PC Valve, have you replaced that?

A hundred thousand miles the plug wires are due, oxygen sensor/s, things are so interconnected that so many single things effect other components.

Curious what engine is it 4.3?

I have a 3.4 that suddenly dropped in MPG, bad injector not closing.

gary350
04-02-2011, 11:45 PM
You checked all the vacuum lines, especially to the PC Valve, have you replaced that?

A hundred thousand miles the plug wires are due, oxygen sensor/s, things are so interconnected that so many single things effect other components.

Curious what engine is it 4.3?

I have a 3.4 that suddenly dropped in MPG, bad injector not closing.

The tag under the hood says 5.7 liter.

How does a person find a bad fuel injector?

I have been out of work 5 years and have no money. The dealer wants $85 and hour and no quanantee they can fix it in an 8 hour shift. That would be $680 plus sales tax I have no money to pay that. I need to do the work myself. I checked the plug wires in the dark there is no arcing to the engine or other metal parts and the engine runs smooth.

Ken_Shea
04-03-2011, 12:07 AM
You likely can get away with out the wires, the oxygen sensor can effect mileage quite a bit and a stuck PCV can cause issues, they are cheap, I always used AC PCV's in GM when I was in the auto repair business.

The engine codes actually pointed to the bad injector.
The mileage went from 26-28 highway to I kid you not 4-5mpg.

5.7 is a V8, it's not likely you will be getting any where near 24mpg.

Presume you are practicing good driving habits, tires a couple pounds over recommended, no long warm ups etc

Another thing and I know it's hard to swallow when you are out of work but I have had good success in using the premium fuel, MPG increases paid for the difference and it has fuel conditioners in it that help keep a cleaner engine.

tdkkart
04-03-2011, 12:56 AM
5.7 is a V8, it's not likely you will be getting any where near 24mpg.


Heh, I'd be amazed if I could verify the 17mpg he's currently claiming, 24mpg is just BS.

All the "economy" chips in the world will not change the fact that you are pushing a land yacht down the road. A vehicle of this size requires a certain amount of energy to move simply due to the laws of physics, all the wishing and hoping in the world can't change that number.

Ken_Shea
04-03-2011, 01:06 AM
Well, that's pretty blunt, unfortunately also pretty factual.

wierdscience
04-03-2011, 01:23 AM
Ethanol in the gas your buying?

When I get stuck with it my milage drops 20% or better.

Yow Ling
04-03-2011, 01:31 AM
Why not swap it for a smaller car, do you need a 6l V8?
In this part of the world not so many people drive V8s , gas is $2.20 per litre about $9.00 for a US gallon. Alot of 1 and 2 litre cars on the road.

lugnut
04-03-2011, 01:57 AM
I've had several 5.7 GMs and 18/20 MPG is as good as it gets, if your using ethanol it gets worse. Wide fat tires will kill you or at least your mileage. IF you can't stand those numbers get a rice burner. :D

saltmine
04-03-2011, 04:20 AM
Ethanol has been driving the gas mileage seekers crazy for a few years now.
What's funny is listening to people trying to figure out why their mileage is in the toilet.

Ethanol has a remarkably low energy content when compared to gasoline.

Gasoline burns at an ideal 14.7 : 1 ratio. Ethanol (by itself) burns at 7 : 1 for the same power.
Almost half.(twice as much fuel for a given amount of air.)
Adding ethanol to gasoline can easily drop your fuel economy drastically.

Example: A 2009 Ford Taurus, with average equipment and care usually gets about 22-24MPG (on the highway). If that same Taurus is a "flex fuel" car, and you can find ethanol, without gas in it, the gas mileage drops to 12-13 MPG (highway). Using Gasohol (10% ethanol by volume), the same car will deliver 16-18MPG. Assuming your Tahoe was getting 18MPG, it probably never will again as long as the Federal Government forces oil companies to add ethanol to their fuels.
Which I find amusing. It actually costs more to process corn into ethanol than it does to refine crude oil into gasoline.

On a serious note: some things can be done to improve your fuel economy. Properly inflated tires is a good place to start (if you're driving around on 24" wheels with skinny "rubber band" tires a foot wide, forget it)
Thermostat. The hotter an engine runs, the more efficient it is. If your temperature gage is laying around on "COLD" most of the time, you're wasting gas. Same goes for coolant sensors for your computer. If the computer thinks the engine is cold, it will richen the mixture to compensate. Oxygen sensors. An old or "lazy" oxygen sensor can waste plenty of gas...they fail reporting "LEAN" to the computer (except on Jeeps)...Vacuum leaks: More oxygen sensors, injectors, and catalytic converters have been replaced because of vacuum leaks than you'd ever believe. Lift kits, luggage racks, piles of junk in the back also cost fuel economy. 100lbs of useless junk can drop gas mileage 1%...think about it.
The correct grade and viscosity of oil helps. I flushed the transmission in my car and replaced the fluid with full synthetic ATF. The gas mileage increased by 1 MPG.
Get your gas at one place. You never know if the owner is "doping" the storage tanks with extra ethanol...We caught a guy locally. The Department of Weights & Measures tested his storage tanks and found he had 65% ethanol in them..Yes, he was fined.

On the subject of injectors: I worked on cars and trucks professionally for over 45 years, and only recall replacing 5 injectors the whole time. Most injector replacements are from mis-diagnosis. Don't believe me? Go to your nearby wrecking yard, and see how many injectors are missing off of the vehicles there...

Uncle O
04-03-2011, 07:06 AM
When it "backfires" on start up , is it in the exhaust, or in the intake ?

aboard_epsilon
04-03-2011, 07:42 AM
Perhaps his 24mpg ..was showing on the computer at a set speed ..which is possible ..

mpg tests should only be done ..by brimming the tank ...doing a set mileage ..then brimming it again and noting the amount put in ..and doing some calculations.

ALL THE BEST.MARK

gary350
04-03-2011, 07:47 AM
When it "backfires" on start up , is it in the exhaust, or in the intake ?

I really can not tell for sure. I can hear a small back fire sound but I never see any smoke. It does not do it all the time and now that I have changed a lot of parts and the weather is warmer it is not doing it as much as it was. The weather is warmer now than it has been every time we have some cold weather move through the engine starts back firing on start up again. The problem seems to have something to do with cold temperatures.

I have tire pressure at 32 psi.

Gasoline around here is 10% ethanol.

I was reading online about different types of fuel and how much power each one produces. Diesel fuel produces more power than gasoline and kerosene produces more power than diesel. I did an experement and put 1 pint of kerosene in a full tank of gas. Gas mileage went up 1/2 mpg and the engine starts and runs the same as before. That was my first experement so I don't put much faith in just 1 experement I need to do more experementing. I hope the kerosene will cancel out the low mpg effects of ethanol.

I turn off the engine every time I stop at a RED traffic light. I timed the traffic lights in town, some RED lights are 45 seconds and some are 3 minutes. This is saving me a LOT of fuel. I am getting about 4 extra days of driving on a tank of gas. Instead of filling up every 8 days I now fill up on day 11 or 12. There are 18 traffic lights between my house and Lowe's and Home Depot. Average time parked at those 18 traffic lights on a 1 way trip to Lowe's is about 15 minutes, round trip is about 30 minutes. How much fuel does an engine burn if the vehicle is parked and the engine idles for 30 minutes??? If I drive around town and stop at the same number of traffic lights every day for a whole week that is equal to having the vehicle parked with the engine running for 3 1/2 hours. How much fuel would that waste???

Rosco-P
04-03-2011, 11:17 AM
You own a re-badged Chevy Suburban and bought it expecting to get "good" mileage? Suburban owners buy them for their size, capacity and towing ability, do you really need it? 100k on platinum plugs and premium wires is about average, time for a replacement. Downstream O2 sensor usually fails first. Best to replace them both, simple wrench work. Diagnostic codes rarely identify specific components correctly, usually points to a faults at a system level.

PixMan
04-03-2011, 11:33 AM
The first and cheapest thing to do is to start replacing every single piece of vacuum hose. It's old enough and gets hot enough under that hood that it's all pretty porous by now.

Willy
04-03-2011, 02:24 PM
Diesel fuel produces more power than gasoline and kerosene produces more power than diesel. I did an experement and put 1 pint of kerosene in a full tank of gas. Gas mileage went up 1/2 mpg.....

Gasoline and kerosene have virtually identical BTU per gallon contents.
Diesel has a significantly high energy content rating.

Did you perhaps forget to include the kerosene added to the fuel tank in your calculations.
A 1/2 mpg fuel mileage difference is extremely hard to pinpoint in anything but a strictly controlled laboratory condition or in thousands of miles of identical driving conditions in order to establish a pattern. A couple of trips to the store just won't cut it. Seemingly small things like temperature, rain, traffic, etc. will all make a huge difference.

RWO
04-03-2011, 04:28 PM
For comparison, I have a 1999 Silverado ext. cab with the 5.3L V8, 3.73 rear end. Running 70 mph on flat ground with A/C on it will average about 20.5 MPG on a 200m trip. Around town, 14-15 MPG is about it. This is burning E10gasoline.

RWO

gary350
04-03-2011, 09:17 PM
I learned something interesting about an hour ago. If a fuel injector is leaking it will cause the engine to burn too much fuel. When the engine is turned off that leaking fuel injector will bleed the fuel pressure into 1 cylinder. Next time the engine is started all the fuel blows out the exhaust and BOOM it backfires.

You guys need to pay attention when you READ.

The 1997 GMC Yukon with the fuel economy chip gets 18 mpg in town and 24 mpg on the highway.

The 1999 Chevy Tahoe with NO fuel economy chip gets 15 mpg in town 17 mpg on the highway.

Here is something that was totally unexpected. Look at how streamlined my 600 lb. camp trailer is. When I pull this trailer at 75 mph on the interstate I get 1 mph better gas mileage with both vehciles. The square back of the SUV is sucking a vacuum producing drag at 75 mph the trailer streamlines the back of the SUV and reduces drag. I have double checked this several times just to make sure there is no mistake.

http://i67.photobucket.com/albums/h292/mikeweaver/td2.jpg

http://i67.photobucket.com/albums/h292/mikeweaver/td11.jpg

hardtail
04-03-2011, 09:39 PM
I agree the backfiring indicates something is wrong........You could try the off the shelf fuel injector cleaners but since you have port injection you might need the vac machine to really clean them......can't recall the proper name for it........I would also consider spark plug wires as good maintenance if you've gone through the rest of the ignition.

Willy
04-03-2011, 09:39 PM
I learned something interesting about an hour ago. If a fuel injector is leaking it will cause the engine to burn too much fuel. When the engine is turned off that leaking fuel injector will bleed the fuel pressure into 1 cylinder. Next time the engine is started all the fuel blows out the exhaust and BOOM it backfires....

Gary there are a number possible causes for an engine to backfire.
A leaking fuel injector is probably low on the list.
Do you know if you do indeed have a leaking injector? Why would an injector that leaks, only leak into the #1 cylinder?

I thought you said you did not know if it backfired out of the intake or exhaust and that it was weather dependent.


I really can not tell for sure. I can hear a small back fire sound but I never see any smoke. It does not do it all the time and now that I have changed a lot of parts and the weather is warmer it is not doing it as much as it was. The weather is warmer now than it has been every time we have some cold weather move through the engine starts back firing on start up again. The problem seems to have something to do with cold temperatures.


Somehow I doubt that you have an injector that only leaks when the weather is cool.

Ken_Shea
04-04-2011, 09:20 AM
There is no way you will be getting better mileage towing the camper, you are likely convinced that you are and it's what you believe that makes something true to you or not.
It may show an increase form the last mileage but all factors are not the same, an increase is not going to happen.

If you don't like the answers Gary, and it seems somewhat apparent from a few of your remarks that you do not, then it's best not too ask for them on a public forum.

All are trying to help, but it is IMPOSSIBLE, yes IMPOSSIBLE to diagnose today's vehicles over the phone or internet, all answers are only a best guess based upon your best guess, not real conducive to accurate solutions.

aboard_epsilon
04-04-2011, 09:34 AM
well Ive towed ..and got better mileage when i towed ..and aint towing stream lined stuff either.

i don't understand why ..
when i posted this on another forum ..a lot of other people said they had experienced same .

I'm not going to argue about it ..that's the info ...it's a strange phenomenon ..that no one can explain ..

that was with a carbed car though .

all the best.markj

Ken_Shea
04-04-2011, 09:43 AM
Sounds like we need to contact MythBusters :D

gary350
04-04-2011, 09:48 AM
There is no way you will be getting better mileage towing the camper, you are likely convinced that you are and it's what you believe that makes something true to you or not.
It may show an increase form the last mileage but all factors are not the same, an increase is not going to happen.

If you don't like the answers Gary, and it seems somewhat apparent from a few of your remarks that you do not, then it's best not too ask for them on a public forum.

All are trying to help, but it is IMPOSSIBLE, yes IMPOSSIBLE to diagnose today's vehicles over the phone or internet, all answers are only a best guess based upon your best guess, not real conducive to accurate solutions.


Every time I drove on the interstate, long trips for vacation I always check gas mileage and it is always the same plus or minus 1/4 to 1/2 mpg. Driving across New Mexico with a 30 mph head wind gave me some extremely low gas mileage once but with no extreme head wind or tail wind my mileage is always within .5 mpg plus or minus. With that in mind if I pull the trailer the mileage increases 1 mph. I know this is not a very scientific test but I have tested this many times probably 15 to 20 times without the trailer and with the trailer. Ok in an attempt to make this a more accurate test I topped off the fuel tank and drove 30 miles round trip back to the same gas station top off the tank and drove the same 30 miles round trip with the trailer, same day, same gas, same road, gas mileage increases 1 mpg. I know this is still not 100% accruate but even if the test if off my 20% gas mileage will still show an increase if .8 mpg. I beleive the square back of my SUV is sucking a vacuum at 70 mph the trailer is reducing the drag and the engine does not have to work as hard at 70 mph. I think a trailer can be specially designed for a vehicle to streamline the back just for the purpose of reducing drag and increasing gas mileage. This will only be efficent at high speed 30 mph city driving it would show very little difference in gas mileage.

Reduced wind resistance plays a very important part in the vehicles ability to go fast with less power. Here is a guy that can pedal a bicycle 82 mph because of low wind resistance, reduced drag. Watch the video.

http://www.edutube.org/video/sam-whittingham-defends-82-mph-world-record-fastest-human-powered-bicycle

Ken_Shea
04-04-2011, 10:03 AM
Here are but a few things that would have to be exactly controlled for there to be any accuracy to the result/claim.

Exact Same Road
Exact Same Gross weight
Exact Same Fuel
Exact Same Amount of Fuel.
Exact Same Speed.
Exact Same OAT Temperature
Exact Same Wind
Exact Same Driving method.
Exact same amount of slowing down speeding up, passing etc.

and more.

It would be impossible to prove on a trip to Disney World.

garagemark
04-04-2011, 10:11 AM
Some of you guys are flat out wrong. A 600 pound trailer is almost nothing to the Chevy, and the pressure differential can indeed raise his gas mileage a tad. A pickup truck gets better mileage with the tailgate UP, not down. The roll of negative pressure created behind the cab with the gate up is better than a smooth airflow across the bed with it down. This WAS done on Mythbusters several years ago.

The leaking injector is a real possibility. Pooled fuel in a cylinder would cause such a backfire reaction, and could be more pronounced in cooler weather.

If you don't have an OBD II code reader, get one. Beg, borrow, or steal one. Get one that has real time drive cycle information. Is your vehicle throttle body INJECTED, or throttle body air flow only with individual injectors in the manifold? If the latter, you can tell with the OBD reader which cylinder bank is using more fuel and/or compensating the other bank. It won't tell you which injector, but it can tell you left or right bank.

Check for vacuum leaks. Use a can of brake cleaner or carburettor cleaner and spray it around fittings, intake, and lines. If you notice a quick drop in RPM, you have found a vacuum leak. Fix it.

Note: Make sure to do tests with the engine hot and the ECM loop is closed. The OBD reader will tell you if it is or isn't.

I believe your engine is designed for 210F water temp. 160 may not close the loop, or may cycle the ECM back and forth.

There is more, but that's a starting point. I just did all these tests on my 6.0? Chevy truck. Ended up as a small vacuum leak causing my issue.

If you are going to work on cars (1996 and up) the OBD II is simply a must. It can keep you from chasing your tail, check engine light or not.

Mark

Ken_Shea
04-04-2011, 10:24 AM
"Some of you guys are flat out wrong'

For sure some one is;), the test on MB was for a tail gate not a 600 pound trailer.

saltmine
04-04-2011, 12:12 PM
Yes, I saw that episode of "Mythbusters" too. And people still refuse to believe that keeping the tailgate on a pickup closed is better, aerodynamically. Oh well....

Somebody remarked that a Tahoe is a "rebadged Suburban"(?) Uh, not nessessarily. The Tahoe is the latest in a long line of Chevy "Blazers" built on a 1/2 ton chassis. Even though the sheetmetal is interchangeable, the Tahoe is designed to seat six adults, and the Suburban nine. The Suburban is also a bit heavier than the tahoe. As far as rebadging goes, yes, the Tahoe is sold under the Cadillac banner as the Escalade. And even though it resembles the Tahoe, the Chevy Avalanche shares a few components.

GM's line of SUV's has been in production the longest of any US manufacturer, and quite possibly the most successful. The first Suburban was manufactured in 1937 to meet a US Army requirement for a "steel-bodied station wagon" utility vehicle. Chevrolet was the first to actually build a station wagon type body on a 1/2 ton truck chassis. (yes, the Suburban comes in 3/4 and 1 ton versions, too...The Tahoe does not).

garagemark
04-04-2011, 01:02 PM
The little 600 pound trailer should create the same pressure effect. It would occur between the trailer and the tail of the vehicle instead of behind the cab in the bed.

Some folks have a propensity to discount anything that is even remotely out of the box. I do not. I cannot discount the mileage claim above, simply because it COULD very well be a true statement. I might call BS if he was claiming better mileage towing a 9000 pound travel trailer (I pull a fifth wheel). But... the trailer in question is little more than two large people in weight, and the disrupted airflow COULD cause a difference.

I do not call BS.

aboard_epsilon
04-04-2011, 02:12 PM
just thought of something.... speedo error

caused maybe by

weight of trailer on back tyres

when this happens the tyres have a smaller radius..but the same circumference

do you guys think there is something going on
only applies to rear wheel drive cars

all the best.markj

garagemark
04-04-2011, 02:33 PM
Ken is quite correct in his statement that there would be no possible scientific way to prove any true mileage claim one way or the other, the exception being possibly a dyno and a wind tunnel. No parameter can be identical at all times.

However, an average study CAN be taken over a period of time, with enough drive cycles over the same(ish) conditions. This is usually sufficient to claim fuel mileages in this type of environment.

I travel the same roads every day to and from work, about 53 miles each way. I have been doing so for four years now, winter, spring, summer, and fall. I check gas mileage with every tank. Yes, I hit one of three stoplights at any given time, and road conditions, along with my speeds, certainly change from one day to the next. I can tell you with pretty good authority that my car gets 33 miles to the gallon. That is the figure I have derived over a very long time.

So, for a given week or two, if my mileage drops considerably, I start looking for a problem under the hood/ drivetrain. Or I look at gasoline brands (I do not fill up at the same place all the time). I usually find some little problem that is causing the differential.

If I get significantly better mileage (doesn't happen), I would just be happy for that week! :)

Ken_Shea
04-04-2011, 03:27 PM
Exactly garagemark,
I do not doubt for a minute that the claims made are legitimate as checked, only that it would be all but impossible for the average driver to substantiate any claim that pulling the little camper give any regular and expected improvement over not pulling.

Personally, I don't buy it but that is not particularly scientific either :D

kc5ezc
04-04-2011, 04:34 PM
My 98 5.7 1/2 ton 4X4 GMC Suburban with 170,000 miles with gets about 13 mpg on the roads back and forth to town. Maybe 17 on the freeway on cruise control. Less with 5% ethanol.
Saltmine: I did not know that GMC (or chevy) made a 1 ton suburban. I need one.
Don't forget leveling the vehicle the same way each time you refuel; just to get rid of one more variable.
Wish I could afford a new 3/4 ton 4x4 suburban. Great people hauler, stuff bringer home, and trailer puller. I have had this vehicle for 4 years
I have always been a ford man, but this GMC has been super.

gary350
04-04-2011, 05:24 PM
Some of you guys are flat out wrong. A 600 pound trailer is almost nothing to the Chevy, and the pressure differential can indeed raise his gas mileage a tad. A pickup truck gets better mileage with the tailgate UP, not down. The roll of negative pressure created behind the cab with the gate up is better than a smooth airflow across the bed with it down. This WAS done on Mythbusters several years ago.

The leaking injector is a real possibility. Pooled fuel in a cylinder would cause such a backfire reaction, and could be more pronounced in cooler weather.

If you don't have an OBD II code reader, get one. Beg, borrow, or steal one. Get one that has real time drive cycle information. Is your vehicle throttle body INJECTED, or throttle body air flow only with individual injectors in the manifold? If the latter, you can tell with the OBD reader which cylinder bank is using more fuel and/or compensating the other bank. It won't tell you which injector, but it can tell you left or right bank.

Check for vacuum leaks. Use a can of brake cleaner or carburettor cleaner and spray it around fittings, intake, and lines. If you notice a quick drop in RPM, you have found a vacuum leak. Fix it.

Note: Make sure to do tests with the engine hot and the ECM loop is closed. The OBD reader will tell you if it is or isn't.

I believe your engine is designed for 210F water temp. 160 may not close the loop, or may cycle the ECM back and forth.

There is more, but that's a starting point. I just did all these tests on my 6.0? Chevy truck. Ended up as a small vacuum leak causing my issue.

If you are going to work on cars (1996 and up) the OBD II is simply a must. It can keep you from chasing your tail, check engine light or not.

Mark

I have been using Auto Zone code reader. I can check the codes at Auto Zone and also online at GMC/CHEVY web site. Code was saying I had an air leak I checked all the vacuum hoses and all the air intake stuff under the hood. The air intake seak had to be fixed and a new gas cap fixed the problem. You are correct about the temperature guage it shows 100.....210.....260. When I start the cold engine the needle is down below 100. After a engine runs a few minutes the needle comes up to 160 then suddenly drops to 150 when the NEW 195 thermostate opens and the water starts circulating through the radiator. The temperature guage shows the engine runs at 150 degrees F all the time. Even though the temperature guage reads 150 if I remove the radiator cap the water boils over. The laws of physics never lie water boils at 212 degrees F elevation here is about 650 ft. The guage on the dash is reading wrong but as long at the computer knows the correct temperature that is OK I replaced the temperature sensor to make sure. With the 6 new parts and repairs the Auto Zone code reader says PASS. Gas mileage has come up from 9 to 17.2 on the highway that is much better but still not what I want. We are having warm weather now so I am not noticing any back fire when I start the engine. Auto Zone and online information both show the 5.7L engine on my SUV has 8 injectors. I can raise the hood and see the throttle body but there is NO fuel rail so the injectors must be inside the intake manafold or thorttle body. Auto Zone has a fuel test kit on tool loan I am planning to use it to test the fuel system pressure. If a fuel injector is leaking the fuel system will not hold pressure after the engine is turned off. If the system is leaking it will not tell me which injector is bad. I was told by a mechanic at a local auto repair shop they can hook my vehicle to a diagnostic machine and find out if the engine is running Rich or Lean. If it is running rich they have the option to make it run Leaner up to a certain amount red line area. I am taking it one step at a time. I still may be able to get my gas mileage up a few more mpg. This engine is rated 255 hp at 4600 RPMs if I loose 20 hp to better gas mileage I will never miss that 20 hp. RPMs are about 1800 crusing at 70 mph on the interstate.

bob_s
04-04-2011, 05:53 PM
If you still have problems with a vacuum leak, make sure that you check the vac-advance diaphragm.

saltmine
04-04-2011, 09:20 PM
Gary350, the reason you don't see a fuel rail or exposed injectors is because you have an "R" code engine. The "R" engine is a 5.7L V-8 with sequential port fuel injectors. The fuel is delivered into the center of the fuel "spider" where the fuel pressure regulator lives and is distributed out to each individual injector through plastic tubes. Early "R" engines had a single centeral injector and small poppet valves on each individual injector, hence the need for a very high fuel delivery pressure. GM soon discovered that the poppet valves were prone to sticking both open or closed, and they also had a tendency to dribble fuel....which led to all kinds of fuel delivery problems and rough running. To start with, GM issued a set of instructions on how to properly clean the injectors, but the cleaning didn't last. So, as a last resort, they produced an "injector upgrade kit" that replaced the "spider", tubes, and pressure regulator with a set of tiny "Multech" type injectors, a wiring harness and new support assembly for the revised "spider". This kit was made available for both the 5.7L V-8 and the 4.3L V-6 engines to eliminate injector problems. The average Mechanic can install one in about an hour.
I've installed quite a few, on both the V-6 and the V-8's and the transition is dramatic. To make it even more attractive, the price of the kit and gasket is actually less money than if you went to NAPA and bought, new, stock injectors, tubes, pressure regulator and gasket. I'll look in my files and see if I still have the GM part number for the kit...

BTW, Bob, GM hasn't used a vacuum advance on any of their engines since the early '80's.

saltmine
04-04-2011, 09:39 PM
As luck would have it, Gary350, I found the part numbers for the V-6. So, I went online and located both the V-8 kit numbers and comprehensive instructions for installing it. Here are the part numbers:

93441235
V-8 MFI Assembly

17113206
V-8 Seal Kit

93442096
V-8 Bracket

You should be able to handle the installation, but if you need help, let me know, and I'll get you that link.

Toolguy
04-04-2011, 09:43 PM
Hi saltmine-
I have a '96 S10 Blazer with a 4.3 Vortec V6. Would this improvement be valid for that model year?

saltmine
04-04-2011, 09:57 PM
Yes, Toolguy, as long as the truck is a '96 or newer. BIG improvement. A 4.3L engine uses a different part number for the kit, and the engine code is a "W" instead of "R"

Here are the GM part numbers for the 4.3L:

12568332
V-6 MFI Assembly

88894355
V-6 Bracket

17113215
V-6 Seal Kit

Like I told Gary, I have the complete GM Service Bulletin and instructions saved as a "Microsoft Word" document, if you need it. I can also convert the document into a PDF format.

Here's a quote from the Bulletin you might find interesting:

"Condition
Some customers may comment on rough idle after start-up, especially if the vehicle has sat overnight. These symptoms may be intermittent. The Service Engine Soon (SES) light may also be illuminated. Current misfire or history misfire codes may be detected with the Tech 2 scan tool.

Cause
A deposit build-up on the CSFI poppet valve ball and/or seat may cause the poppet ball to stick open or closed. In either case, the specific cylinder will be mis-fueled, resulting in a cylinder mis-fire condition."

Toolguy
04-05-2011, 12:03 AM
Thanks a lot saltmine! I really appreciate that!:D I didn't think to ask at the time - do you have a ballpark idea of how much these parts cost? Tens, hundreds, thousands? Yes - I could use the service bulletin and instructions as a PDF. wmoore5@kc.rr.com
Thanks again.

lazarus
04-05-2011, 01:23 AM
My brother in law had one of those GM spiders take a dump on his 5.7L Suburban. The dealer wanted $600 for the part. He bought the aftermarket stainless kit for $350(I think it was Edelbrock).

I was delivering to Delphi, asked the receiver what they made there. He said, "the fuel spiders for GM 5.7L. I told him what we had done. He told me to wait a minute, left, came back and handed me a Walmart bag. He said he looked at the cost analasys of that part. It cost them $68.00 to make the entire setup-right here in the good ole USA. I told him I couldn't take it, he said,"B@$*Sh#% they shouldn't tell you to keep your GM vehicle GM, then make it so you can't afford to.

It's funny how the dealer could justify almost 900% markup on a part that only has one middleman(the distribution center)

gary350, if you find the spider to be defective, and I can find it in the shed, let me know. You can have for the shipping. If you want the Walmart bag it came in, that will cost you $599 extra-it's one of the old white ones you can't see thru...ie-vintage:D

saltmine
04-05-2011, 02:07 AM
Well, here's the shocker. The whole injector upgrade kit, from GM, retails for $368.50 (MSRP).
You can buy the same, identical kit from "GM PartsDirect" (online) for $259.08. I imagine there's tax and shipping costs involved, but it's nowhere near the $600 the dealer quoted. The entire job only pays 1.4 hours labor, and even at $100 an hour....well.....Somebody is getting tubesteaked...

The V-6 injector kit is a bit less: $351.02 (MSRP) and $179.43 from "GM PartsDirect". Again, the labor is 1.4 hours for the installation.

The last kit I personally bought was about 8 years ago, for a 4.3L V-6 and at the time it sold over-the-counter for $150 at a GM dealer in Phoenix.
I installed the kit in 45 minutes, myself.

Here's the GM partsDirect URL: http://www.gmpartsdirect.com/results.cfm

BTW, the Edelbrock kit is the original, stock CMFI spider, or the marine stainless steel spider(with poppet valves). GM (Delphi) is the only one who makes the factory drop-in upgrade kit.

On an additional note, Lazarus, when I worked at a GM dealer out on the "Left Coast", it was common practice for dealer parts departments to "double-net" all of the parts they sold. Basically, they would look at what they had to pay for a part....and double it.

lazarus
04-05-2011, 03:57 AM
"saltmine" On an additional note, Lazarus, when I worked at a GM dealer out on the "Left Coast", it was common practice for dealer parts departments to "double-net" all of the parts they sold. Basically, they would look at what they had to pay for a part....and double it.


Yeah, go to a city like Virginia Beach and let them see a military base permit on the front bumper. My guess is they think members of the armed forces make as much money as government contractors.

Hasn't been any problems with the Edelbrock system. Do you know if the upgrade will work with it, should he ever have any issues?

gary350
04-05-2011, 09:38 AM
Saltmine are these parts for the Chevy Tahoe?

Do I get these at Auto Zone or the dealer?

Wonder how much they cost?

I SOLD the GMC it was having transmission problems. I wish I had it back it was getting much better mileage than the Chevy Tahoe.

93441235
V-8 MFI Assembly

17113206
V-8 Seal Kit

93442096
V-8 Bracket

I use to work for a company where we made parts for Ford, Chrysler and GM. The parts cost us from 40 cents to $2 to make depending on which part. I checked with the dealer just to see how much the parts were selling for prices were $198 up to about $300. That should be illegal they know you have to have it so what can you do but pay the price.

saltmine
04-05-2011, 11:54 AM
I've never worked with the Edelbrock system, but Edelbrock usually stands behind their products pretty well. If they don't perform properly, Edelbrock won't put his name on them.

All of the part numbers I listed were GM part numbers, Gary. If you can find a decent auto parts store, they should be able to cross the part numbers over to their product line. But, I wouldn't recommend it. The parts listed are for a V-8 Tahoe.
When I needed a spider assembly and injectors for a 2000 Blazer the County owned, I called NAPA auto parts (our usual supplier) and was told the stock replacement parts (not upgraded) were going to be roughly 30% more than the GM kit, and would leave the Blazer with the same potential problem it already had. I went with the kit, and got a "cookie" from my boss for saving the County money...
Another thing I forgot to mention earlier was the fact that the fuel pump was starting to lose pressure, too. But the "Multech" type injectors and regulator didn't care, they perform perfectly all the way down to 30 PSI without any issues.
That's how you determine which injectors are "the good ones". "Multech" injectors are electronic, and have both a fuel line and an electrical harness leading out to each injector. The stock, troublesome poppet valve injectors just have a plastic line to each one.

Yeah, it should be illegal. But what can one do. You get what you pay for.

Ryobiguy
04-05-2011, 03:07 PM
It actually costs more to process corn into ethanol than it does to refine crude oil into gasoline.
...
Get your gas at one place. You never know if the owner is "doping" the storage tanks with extra ethanol...We caught a guy locally. The Department of Weights & Measures tested his storage tanks and found he had 65% ethanol in them..Yes, he was fined.


If ethanol is so expensive, then why is a shady gas station operator going to pour $$$ down the drain into his tank by doping it with way too much ethanol?
I guess that story shoots down what your first statement was implying.

-Matt

gary350
04-05-2011, 03:22 PM
Saltmine. I got the fuel pressure test kit at Auto Zone today. The book says fuel pressure should be 60-65 psi. With the engine running fuel pressure is 54 psi. Just as soon as I turned the engine off pressure jumped up to 60 psi and held there for 15 second. Pressure slowly dropped to 58 psi in about 60 seconds. Pressure held at 58 psi 15 minutes later pressure was down to 57 psi. Pressure dropped down to 56 psi after another 15 minutes. It appears the pressure will continue to drop about 1 psi every 15 minutes. I pushed the button to release the pressure and about 20 drops of fuel came out.

Is this normal?

I assume a bad injector would leak down faster than this.

saltmine
04-05-2011, 04:30 PM
Judgng by the wildly differing amounts of accuracy and calibration among fuel pressure testers, it's probably a bit low. That would lead me to suspect the fuel pressure regulator on your injector unit. With the regulator in the circuit you never get an accurate estimate of the real "deadhead" fuel pressure is.

The regulator is important in a poppet valve system to maintain pressure in all of the lines right up to each poppet. If you have a failing (or leaking)regulator, fuel can make it's way into your crankcase oil, and skew your fuel calibration. Should a poppet valve stick or seat improperly, you will lose fuel pressure there, too. A drooling injector nozzle can raise hell with fuel calibration also. The "KIT" addresses this problem with a set of good quality electronic injectors.

I often wondered about that myself, Ryobiguy, but then a factory engineer gave me a "hint" of what was really going on at the gas station level....
water. Water is free, and with a significant amount of ethanol in the storage tanks, water will easily mix with the ethanol and gasoline. Like getting free gasoline from a garden hose.

gary350
07-28-2011, 04:34 PM
UPDATE. The Chevy Tahoe is fixed. The problem was, all the fuel injectors were running wide open all the time because of low fuel pressure. Low fuel pressure was caused by a dirty fuel filter.

Black_Moons
07-28-2011, 04:42 PM
UPDATE. The Chevy Tahoe is fixed. The problem was, all the fuel injectors were running wide open all the time because of low fuel pressure. Low fuel pressure was caused by a dirty fuel filter.

hahaha. Yep. Gotta check the basics.

Amazing how complex problems can be caused by simple things?

My friend has an RV.. when he got it, it would continiously flood the horrabley ruined carb. It was ruined because someone tryed to fix it from flooding 9 too many times.

Before it flooded, Im pertty sure it starved. Why? Because theres an aftermarket fuel pump installed right at the tanks... Powered from the RV battery, Not the engine battery no less!

Why did it starve? Im guessing fuel filter.. :) But I digress. We put in a brand new (rebuilt) carb, Rebuilt from some other carb because by then, the carb in the RV was only good for the non standard linkages needed to connect the carb up, it was that ruined.

So, we put the carb in, Power the engine up and.... Floods!
.. Back to reading up online.... Turns out these carbs flood a lot... When the fuel pressure is too high. 10psi being too high. buy $10 pressure tester.. 14psi! Buy $70 fuel regulator, Problem fixed.

Im still wondering if the fuel filter was ever changed or if its just gonna ruin stuff when that added pump can't push through it anymore.

steve45
07-28-2011, 10:57 PM
Glad you found the problem--and it was simple!

I've got a '97 Tahoe with 368,000 miles on it. On the road at 70 MPH, it will give 18.5 MPG day in and day out. I used to drive 300 miles per day and fill it/calculate mileage every day. Any change in mileage was my indicator that something was wrong.

When I bought the vehicle (with 30,000 miles) it averaged 17.0 MPG. A customer suggested going to a K&N air filter. With the MAP sensor, I couldn't see how it could possibly improve mileage, but it did--measurably. Some people badmouth the K&Ns, saying that they pass too much dirt. Well, I live in West Texas, which is about as dry and dusty as you can get (we've had less than a half inch of rain in the last 9 months). My engine uses about a quart of oil every 5000 miles, which I don't think is excessive.

As far as spark plugs, I changed the original plugs and wires at 200,000 miles. I measured the gaps on the plugs and they were worn less than .003". There was no improvement with new plugs and wires, only increased ignition noise on the radio. In my opinion, with the precious metal plugs and unleaded fuel, plugs are a lifetime part. No reason to ever replace them.

As far as the trailer pictured, yes, I believe that it certainly could increase the mileage. It's shape is very similar to the drag reducing cowling that was used on radial engine airplanes. The sliding canopy on my airplane (Navion) is similar. The airplane can be flown with the canopy slid back, but in flight, it wants to move forward. There is a cable arrangement to allow the pilot to pull the canopy open, aerodynamic forces actually push the canopy forward to the closed position.

bborr01
07-28-2011, 11:15 PM
Gary,

Glad you got your ride running good. Keep us posted on your mileage when you get a record of it.

A friend of mine ran a fairly large auto repair facility.

One day I asked him what is a repair that people could do to save money later.

He said that's easy: replacing a fuel filter. A fuel filter usually costs less than $20 for the part and is easy to replace.

A fuel pump costs $300 to $600 to drop the tank and replace the pump. Having a plugged filter makes the pump work harder and fail prematurely.

Which reminds me, my Trailblazer is due for a fuel filter.

Brian

justanengineer
07-28-2011, 11:50 PM
If it takes more than three revolutions to start...I put a filter in.

With fuel filters today, you have to be really careful what you buy. They should be stainless, but many of the parts chains sell cheap lightly galvanized tin fuel filters and IMHO these can be rather dangerous to the average vehicle owner. When I was still wrenching for a living, one of my favorite customers' cars burned up due to a combination of road salt, a cheap non stainless filter, and 50 psi fuel pressure. To answer the unasked question, no I wasnt the one that installed it nor did I know about it until too late.

Bill736
07-29-2011, 12:26 AM
I've solved a few fuel injector and fuel system problems by adding Chevron Techron Fuel System Cleaner to the gasoline. It's an easy, and cheap, first step before you dive into more complex fixes.
And, to add to the mpg data base, my 2000 GMC Sierra pickup with the 5.3 liter V-8 engine and overdrive automatic averages 17.3 mpg overall. I'm pleased with that number.

J Tiers
07-29-2011, 09:43 AM
Exactly garagemark,
I do not doubt for a minute that the claims made are legitimate as checked, only that it would be all but impossible for the average driver to substantiate any claim that pulling the little camper give any regular and expected improvement over not pulling.

Personally, I don't buy it but that is not particularly scientific either :D

1) ANYONE can check mileage pretty accurately......

2) OF COURSE the trailer can improve mileage

3) If you don't like the miles per gallon figure for ethanol, then check it out as miles per kg. Ethanol is lower in density, but per unit mass the energy content will look better. Hardly any drop for even E85. Now if they would just charge on that basis........
*
*
*

To check mileage, don't rely on one fillup and the odometer, UNLESS the mileage is a lot different, in which case you can see it just fine.....

Unless you fill the same amount and all the tiny contributors you commented on are the same, a 0.5 or 1.0 mpg number change is well within error limits.

BUT if the mileage drops 20 or 30%, you can KNOW something is wrong, and no BS about headwinds etc has to be even mentioned... it's irrelevant.

And history with a route makes a difference

I have distances I drive regularly..... 1000 mile trips. I know where I will need to get gas, and they are the same places regardless of wet roads, weather, temperature, winds, etc, plus or minus a few miles. I KNOW I can get from St Louis to near Lima OH on a tank, any time of the year.

if I needed gas in Dayton, or Knightstown, I'd know something was up.... I don't have to carefully balance all the minor effects you claim discredit mileage results.



*

A lightweight trailer can and DOES add length, as well as possible streamlining. Length helps with net air resistance, it acts a bit like streamlining.

if the trailer is not so heavy as to add a significant amount to the load, that's better, of course. A very heavy trailer would cut mileage from that cause alone, regardless of shape.

aboard_epsilon
07-29-2011, 10:06 AM
Fuels that are higher octane are only of benefit, if your car has the equipment to recognize this ..by detecting knock fresh-hold and adjusting timing to suit

My present car, has a knock sensor and only adjusts the timing to prevent knock....So using my higher octane lpg ..it does not compensate.

My old car was a bit primative..i ran that on lpg.......it had fly leads that you could interchange to move the timing more towards tdc ...3 and 6 degrees to prevent knock on poor fuels ..i took advantage of this ..i moved the dizzy around, so it was at 14 degrees before tdc instead of 8...and used the fly leads connected to a switch in the cabin, to switch back to 8 when i was running on petrol.

other more modern cars will take the car right up to the knock point automatically...so will take advantage of higher octane fuels.

not all of them do it though .

ALL THE BEST.MARKJ

J Tiers
07-29-2011, 11:44 PM
Fuels that are higher octane are only of benefit, if your car has the equipment to recognize this ..by detecting knock fresh-hold and adjusting timing to suit

My present car, has a knock sensor and only adjusts the timing to prevent knock....So using my higher octane lpg ..it does not compensate.



Perhaps the adjustment has an effect on mileage? having to fix the timing from what it "should" be is unlikely to *improve* the MPG......

On that basis, the higher octane could help by allowing an optimal timing, instead of a radically "de-tuned" and adjusted one to compensate for knocking.

A.K. Boomer
07-30-2011, 12:15 AM
There is no way you will be getting better mileage towing the camper, you are likely convinced that you are and it's what you believe that makes something true to you or not.
It may show an increase form the last mileage but all factors are not the same, an increase is not going to happen.

If you don't like the answers Gary, and it seems somewhat apparent from a few of your remarks that you do not, then it's best not too ask for them on a public forum.



Ken - you need to learn a thing or two about the energies required for overcoming air drag at certain speeds in comparison to rolling resistance and such, higher speeds and things get way lopsided...
It's not only entirely possible to get better mileage while pulling something light it's actually well documented --- it's called an "aerodynamic long tail"
and it's why a tapered turd will go way faster down the sewer pipe than a blunt backed one - even if the taper turd is twice as long...

fluid dynamics are very similar - ever see a blunt back fish? nope ----- - Garys not imagining anything - he's actually very observant - his little light weight trailer that's a far better shape the the flat back of his truck is piecing the air back together before it leaves and this creates less overall drag on the vehicle - enough to make up for the tire friction and bearings of the trailer - and then some...

Magnum164
07-30-2011, 09:32 AM
Love those Yukons, had a 1995 that I loved. However when I got married I had to get something that got better than 6MPG in the city. Taking step-kids to and from activities was killing us.

Of course mine did have a 400+HP 383 stroker stuffed under the hood and was 4x4.

http://i60.photobucket.com/albums/h15/kd4vcu/Cars/05250022.jpg

aboard_epsilon
07-30-2011, 10:08 AM
Perhaps the adjustment has an effect on mileage? having to fix the timing from what it "should" be is unlikely to *improve* the MPG......

On that basis, the higher octane could help by allowing an optimal timing, instead of a radically "de-tuned" and adjusted one to compensate for knocking.

On the older car it was open loop lpg..i did quite a few things on it to improve the mpg ..

that was one of them ..

the system on it was a bit restrictive ..doughnut shaped mixer.
about 15 mph off the top speed and about 20 percent less acceleration..
still i got 38 mpg on a run with lpg compared to the same on petrol

my present system ..i have no facility for adjustment of timing ..and its sequential injection lpg..

it does on long runs 41 mpg on petrol ..and only 31 on lpg :(

all the best.markj

saltmine
07-30-2011, 12:03 PM
Gas mileage can be an incidental thing...Depends on what you're using the vehicle for.
My nephew, bought a brand new Dodge Neon SRT-4 with a turbocharger.
It went like jet stink, but there was barely enough room for two people inside it. He added a stage III kit and made it even faster, until the flywheel fell off, three blocks from home. Yeah, the dealer fixed it, no charge.

But when he got married, and realized they had a little one on the way, he started looking around for a "family" car....And, since gasoline prices were starting to climb, he decided the "family" car was going to have to be somewhat economical. His son was born and the SRT-4 continued to soldier on. His wife complained sometimes about having to make two trips to the store to get everything, and naturally, the ride quality was horrible.

When the second child was confirmed, on the way, he looked even harder.

He finally settled on a well-cared-for 2003 Chevy Suburban 1/2 ton, two-wheel-drive, 5.3L V-8. A deal was struck, and very little money changed hands.

Much to their surprise, the Suburban, with it's limousine-like ride, and ample room for everything, was getting almost double the fuel economy the Dodge SRT-4 was. And, his wife discovered she could go shopping once, and bring everything home in one trip. They have been driving it now for four years, and outside of a new set of tires and a battery, the Suburban has done it's job without the slightest problem. It still delivers remarkably good gas mileage, and his wife has grown attached to the beast.
They go on family trips, shopping, and never have to leave anybody home, or go back for them later.

My nephew firmly believes that if he'd kept the Neon, they would never have been able to do so many things together, as a family. And, he also is convinced the Dodge would have turned itself into a lawn ornament long ago.

gary350
08-21-2011, 05:56 PM
After driving my vehicle 2 weeks the gas mileage is worse than every 10 mpg. The dealer wants to do tests and replace parts to find the problem. It could cost $1000 or more and no guarantee they can fix it. I don't like giving anyone a blank check so I am back to square one.

I checked online one person had a low mileage problem that was caused by the fuel regulator pressure being too high. Wonder how to test that and where is the pressure regulator.

Another person had 2 fuel injectors leaking.

I did a search I cannot find any photos of what my fuel injector system looks like. I am sure it is inside the throttle body but I have no idea what tools or gaskets, etc I will need if I take it apart. I want to install the new upgrade fuel injector system myself I wish I could find a video on You Tube to see how it is done.

Arcane
08-21-2011, 06:09 PM
Maybe you could buy a service manual on Ebay...

Boostinjdm
08-21-2011, 06:12 PM
I did a search I cannot find any photos of what my fuel injector system looks like.

Try opening the hood....

IF it's throttle body injected, you will have a couple injectors sticking out of the throttle body. It's fairly obvious, they'll have wires and fuel lines running to them.
IF it's multiport injection, you will have 8 injectors in the manifold just inside the valve covers with most likely a steel or aluminum fuel rail and wires running to them.
When in doubt, buy a book.

gary350
08-21-2011, 08:53 PM
Try opening the hood....

IF it's throttle body injected, you will have a couple injectors sticking out of the throttle body. It's fairly obvious, they'll have wires and fuel lines running to them.
IF it's multiport injection, you will have 8 injectors in the manifold just inside the valve covers with most likely a steel or aluminum fuel rail and wires running to them.
When in doubt, buy a book.

Every thing I read says, there is 1 fuel injector, 1 fuel regulator, and 8 popits inside the throttle body. The new upgrade kit has 8 fuel injectes and the regulator inside the throttle body.

saltmine
08-21-2011, 09:32 PM
Yep, Gary, that's the sequential injection system. If you were to remove the upper plenum (plastic), you would see one fuel line entering the "spider" and one exiting it. Of course there's eight plastic pipes connected to 8 poppet valves just above the intake ports of the cylinders. The pressure regulator is inside the "spider"... Your 1999 engine is an "R" engine. Check the 8th number of the VIN...it will be "R".

Sticking injector poppet valves.

Though it was reliable and simple to work on, GM discontinued the Rochester TBI system on all their vehicles in 1994. After 2000 GM went to the GEN 3 "LS" type engines which are fitted with port injection and COP (coil on plug) ignition systems.

Boostinjdm
08-21-2011, 10:02 PM
Every thing I read says, there is 1 fuel injector, 1 fuel regulator, and 8 popits inside the throttle body. The new upgrade kit has 8 fuel injectes and the regulator inside the throttle body.

I didn't look up your vehicle. Just saying what I've seen and believe to be common.

saltmine
08-21-2011, 10:06 PM
Here's a couple of photos of intake manifolds from Chevy V-8's


http://i643.photobucket.com/albums/uu155/saltmine_album/injection.jpg


The one on the left is a sequential injection manifold off of an "R" engine.
The other one is a late model port injection manifold from a newer engine.
The throttle bodies have been removed so the sequential injection "spider" can be seen (it's that rectangular item in the back of it, with the silver colored lines....those are the fuel lines from the filter) Of course to get a better look at the "spider" you need to remove the upper manifold. Those fuel lines need to come off too.

saltmine
08-21-2011, 10:23 PM
OK Gary, here's a page from NAPA's online web page.


http://i643.photobucket.com/albums/uu155/saltmine_album/add.jpg

The single injector at the top is a poppet valve injector with it's plastic fuel pipe.

The photo below is a photo of the MFI conversion kit..which NAPA now sells..

garagemark
08-22-2011, 10:19 AM
Once again, I'm advising anyone who's going to work on their own vehicles to go buy a DECENT OBD II READER. Get at least the mid-level model with real time drive cycle data (the next step up is a data recorder). It'll cost you about 85-90 bucks and you'll have it forever. It is much easier to get on a forum and tell them that "my throttle position shows XXX% open (TPS)" or "my MAP sensor shows XXX".

I do not concentrate so much on MIL (malfunction Indicator Lamp)(Check Engine Light) codes unless the code(s) are very self explanatory. You can have bad things going on in the engine and/or emission system that won't set a code until they get real bad.

I know that you (we) are concentrating of fuel delivery in this thread, but there are a whole host of sensors, percentages, temperatures, and other parameters that can cause your ECM to tell the fuel system to deliver more/ too much juice. You may actually be looking at a symptom, not a root cause.

It's just been my limited experiences......

Mark

saltmine
08-22-2011, 12:47 PM
Most of the time, it's a good idea, Mark. But, in this case, the solution is quite obvious. No, I didn't need a $50 to $80 code reader...mainly because even the more expensive DIY code readers available don't do real-time or live data display. I went looking recently with a friend who wanted something that would give him a bit more information than a glorified paperclip. The cheapest scanners we found were over $200, and you had to be careful which one you got, because year model and application coverage is spotty at best. When I was working, we had a couple of professional grade scan tools (note: I said scan tool....not "code reader") they were good sized and expensive ($3500-$4000) and had to be updated every year ($1000 to $1500 per year). But they delivered more data than the average "home mechanic" would ever be able to use. They were also bi-directional, which means you could initiate tests and turn on and off functions from the scanner. But, no matter how much you paid for a scan tool, it takes years of experience to turn the data being displayed into something one can understand. A common pitfall of "code scanners" is trying to solve the problem with displayed codes. Most of the time, a displayed code isn't the problem, it's something making the code show up.
Most of the DIY retail auto parts stores offer to scan your car for codes. Unfortunately, the guy operating the scanner is usually not qualified to use it, and, believe it or not, hundreds and thousands of oxygen sensors, TPS's, map sensors, MAF sensors, and catalytic converters are sold DAILY because of these poorly deployed scanners.
Gary's problem was fairly easy to diagnose.
But too many guys want to dash off "willy-nilly" testing single wire resistance and flux capacitor density%, when it's usually (90% of the time) something simple.
That's the frustrating thing about offering advice on forums. Even if you're right, there will be 25-30 guys out there who will smugly state "You don't know what you're talking about." Sometimes the negative comments get so bad, that I leave the web-site or refuse to post comments....much to the dismay of the guys who really need the help.
I offered, the ball is in your court, Gary.

garagemark
08-22-2011, 03:38 PM
Gary, indeed you can purchase scan tools for many thousands. But for the home mechanic, this little devil does a pretty good job:

http://www.actron.com/product_detail.php?pid=16362

Actron has it listed for $144. Mine cost $85 with a little shopping. It WILL do real time data, as well as read MIL codes and erase them. It is actually quite interesting what you can see while doing a drive cycle. I don't need to know what all the numbers mean, but when I go to a forum of car people for my car specific, I can tell them the data during a drive cycle, or idle, or anywhere in between. And I have gotten great results from doing just that.

Will it do what a professional instrument can do? No. But it has helped me several times find an issue that, on the surface was one thing.... but was caused by something else entirely.

Oh, and by the way- I don't really think you can expect Kia fuel mileage with a V-8 monster grocery getter. If he does figure out how to do it, he'll certainly be rich. ;)

Black_Moons
08-22-2011, 04:48 PM
Oh, and by the way- I don't really think you can expect Kia fuel mileage with a V-8 monster grocery getter. If he does figure out how to do it, he'll certainly be rich. ;)

I allways liked the idea of those V16 (Caddy?) motors that can shut down cylinders to become a V8 or V4...

However I suspect they don't clutch the crankshaft, And even if you do something funky and lock the intake valves open (and/or exhaust valves? I doubt you'd wanna suck exhaust in/outta a non operating cylinder, or let intake/exhaust mix), you still have pumping losses.... But the remaining cylinders can run closer to WOT to reduce pumping losses...

gary350
08-22-2011, 07:27 PM
I talked to several mechanic today some said it could be fuel injectors, some said it could be bad catalitic converters, some said if you want to keep guessing replace the spark plug wires and rotor next, they all said it is best to get a full diagnostic if you keep throwing money into new parts it is going to get expensive before you find the real problem.

I checked with the dealer I was told $95 per hour for labor and $400 for the diagnostic. I"m not ready for an enema yet.

I checked with the local Automotive School they said $5 for diagnostic but you have to wait 2 weeks.

Black_Moons
08-22-2011, 07:56 PM
I talked to several mechanic today some said it could be fuel injectors, some said it could be bad catalitic converters, some said if you want to keep guessing replace the spark plug wires and rotor next, they all said it is best to get a full diagnostic if you keep throwing money into new parts it is going to get expensive before you find the real problem.

I checked with the dealer I was told $95 per hour for labor and $400 for the diagnostic. I"m not ready for an enema yet.

I checked with the local Automotive School they said $5 for diagnostic but you have to wait 2 weeks.

So,The question is: Do you plan to burn more, or less then $395 in gas in 2 weeks? :)

MrSleepy
08-22-2011, 08:07 PM
It might be cheaper to p/ex it at the dealers for one with lower mileage ..and more mpg.
Then the next buyer can get the dealer to fix it under warranty.

gary350
08-22-2011, 09:38 PM
New discovery. I have about 11,000 miles on the new spark plugs. I removed all the spark plugs 3 of them look like the cylinger is running lean. The gap on those 3 plugs have change the tiny little needle wire is burned shorter gap is, .092, 096, .099 not .060 like it should be. I regapped them all to make sure. It was getting dark and I tested each plug hanging on the end of the spark plug wire with the engine running. They all spark but there is NO nice blue spark. They all have a very orange spark like a match or candle burning. I don't think orange is right??? If there is a capacitor in the circuit it must be bad.

The engine only has 111,000. miles not much of a 1999 vehicle.

saltmine
08-22-2011, 11:05 PM
Now that really hurts...."I talked to several mechanic today and some said it could be injectors, some said it could be catalytic converters, etc, etc, etc..."

What am I? Chopped liver? I guess your local mechanics have all of the GM and ASE certifications, A/C license, and a California emissions license. Not to mention 45 years of turning wrenches on everything from lawn mowers to diesel semi trucks....

Makes me want to scream...I'm offering to help, and you want to listen to a tatted out, pinball wizard...just because he works "down the street"...
Maybe that's it...I offer my help for free....Would it make you feel any better if I charged you $100 an hour for it?

Scan tools? I used to teach people how to use scan tools!


Sheesh! Give me a break!

J Tiers
08-23-2011, 12:12 AM
As a point of info, which may or may not relate...

On SOME GM vehicles, the fuel pressure is apparently set by a bleedoff valve on the fuel filter.

I have an S10, 2000, and that is apparently the case. I had bad mileage, and an oxy sensor code thrown.

Dealer had just replaced the filter, and the POS had a bad bleedoff valve, that set the fuel pressure 25 lb high.

After the free replacement, all was back to the normal 25 or so mpg.

flutedchamber
08-23-2011, 12:43 AM
New discovery. It was getting dark and I tested each plug hanging on the end of the spark plug wire with the engine running. They all spark but there is NO nice blue spark. They all have a very orange spark like a match or candle burning. I don't think orange is right??? If there is a capacitor in the circuit it must be bad.

The engine only has 111,000. miles not much of a 1999 vehicle.

How did the engine run with all of the plugs out of it? The spark won't be blue if you have a piss poor ground for the plug.

gary350
08-23-2011, 08:50 AM
Now that really hurts...."I talked to several mechanic today and some said it could be injectors, some said it could be catalytic converters, etc, etc, etc..."

What am I? Chopped liver? I guess your local mechanics have all of the GM and ASE certifications, A/C license, and a California emissions license. Not to mention 45 years of turning wrenches on everything from lawn mowers to diesel semi trucks....

Makes me want to scream...I'm offering to help, and you want to listen to a tatted out, pinball wizard...just because he works "down the street"...
Maybe that's it...I offer my help for free....Would it make you feel any better if I charged you $100 an hour for it?

Scan tools? I used to teach people how to use scan tools!

Sheesh! Give me a break!

I went to several shops to check prices to see if I can get someone to fix it at a reasonable price. When they said it is the fuel injectors that confirms what you said. When they said it is the cat converter that makes me wonder if they know what they are doing I had a Toyota once several people said it needs a new converter. After replacing the converter the exhaust manafold still turned red hot from the engine block down about 3 ft below the engine. When people tell me it needs a new converter I naturally thing, yea right. When someone suggests new wires and dis cap that is work I can do myself and it is cheap and easy its worth a try. I have had several vehicles that needed new wires and distribtur cap after 100K miles. So I think I will change the wires today. It 2 weeks I can get the Automotive School to change the injector spider. Auto Zone has the spider $299. O Reily has it $317. The dealer has it $600. The spider at Auto Zone and O Reily are not 100% identical the pressure regulator is a little different wonder why.

The guy at Auto Zone said he has changes the spiders himself so we raised the hood and he told me how to do it. I can do it myself too but it will be easier to let the Automotive school do it, I buy the parts the students get the experience.