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The quest for higher MPG's (Phase II)

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  • The quest for higher MPG's (Phase II)

    Im getting ready for the second phase for the quest for better economy, Iv posted phase I and for the most part its essentially something within most everyones grasp, tire pressures, synthetic lubes and driving habits -- My progressive ratio throttle control is a nice help but not a must as if you pay attention you can still achieve great "metering" results. With phase I Iv taken a car thats rated 33mpg (highway) and have achieved over 50mpg's and that is in all actuality with a little mixed and slightly hilly driving, so im well into the 50's,

    Phase II will be much more involved and requires me to tap into my engines computer and overide certain situations, it differs from my first attempt in that now im entering an area where if i get too carried away I can cause detrimental damage to the power plant, My new gauges came in and right now im just getting used to where My engine has been "living" and how much elbow room I have to make improvements, I have found that I actually have much room for efficiency improvement but there is also much to consider in many situations -- and although i plan on having an economy "mode" for all driving conditions the gauges have shown me that I should make the best gains in a "controlled environment" -- this equates more to highway as it will allow me to dial in the perfect mix (well perfect for this phase)
    I believe I will break into the 60's but I dont know if I could do it with any mixed/hilly conditions, we shall see -- at the very least it should be interesting ( I am going to actually wax the car it as it hasnt been in years and also add a missing cowling/underbelly panel thats been missing)

    Here's a pic of my new little babies;

  • #2
    While I cannot justify it as yet I do have one more trick up my sleeve and if gas gets over 5 bucks a gallon I will seriously consider using it,
    Phase III would require me to buy three more exhaust temp probes -- and reposition the one I already have -- the goal would be to carefully monitor each individual cylinders exhaust temp. (instead of right now having the single probe in the collector pipe and taking a reading of all together) I will still keep just one gauge and use a switch board, much attention to detail will be given to the variance in temperatures as this will indicate that some injectors are working better than others -- I do not know what to expect here as im not sure how close toyota keeps tabs on this and also the effect of what 211,000 miles has on them, so it might take many processes of elimination and trips to salvage yard to come up with the perfect injector match, also temp probes will be swapped out and tried in different ports to verify that they are within strict parameters , all this effort is not so I can achieve the closest temperature to rich side without going to lean -- in fact its quite the opposite --- What I want to achieve is to go past the critical EGT's and onto the other side -- its called LOP or lean of peak - while many pilots know about this many also stay away from this school of thought because theres a very small window on the other side -- generally ROP (rich of peak) is the typical method thats used and been used very effectively over the decades --- LOP however is for real and is also regaining popularity with the extreme price of av-gas --- its not only been around since the days of Charles Lindbergh, There are now some major refined products (injectors and gauges ect.) that are going ballistic in the aviation market place -- not only that - its even gaining exceptance with some major aviation engine manufacturers --- done up right LOP can actually make an engine run cooler/last longer because once you do cross over to the other side and properly meter the ratio to the very lean you simply do not make enough heat there to do any damage, its way "cool" --- your biggest threat is not too lean (go any leaner and the engine will stumble), its actually a mismatch in injectors and having an injector thats a little on the rich side, this can throw that cylinder into direct peak exhaust temps and into a detonation chaos.
    The drawback for me is I can only adopt this on long stable highway cruises -- there is to many variables in throttle position and traffic and on and on for this to be practical anywhere else - it can be done on the highway, but it better be a very stable highway -- i would also be using premium fuel for added protection against detonation, also things for me to consider are that by a performance standard most N/A airplane engines are slugs, they also use fuel that has an extreme octane rating, my car engine has a much greater opportunity of hurting itself BUT---, LOP can be utilized even in the 60 percentile range of max power output of an aviation engine (and some claim much higher) , While im well under 20 percent of MPO going down the highway (and in all actuality closer to 10), and I wouldnt be using LOP for anything but.
    It would take desperate measures for me to justify this -- but if I did it all of the GPH ratings and percentage gains that have been proven by LOP aviation stats would have to put my little car well into the 70mpg range.
    For right now im content putting my focus into phase II -- I will post the progress along the way.
    Last edited by A.K. Boomer; 06-11-2008, 12:32 PM.


    • #3
      Remember the old Honda CVCC??

      Swirl chamber technology.. how about another injector dropping pressurized air stream across the port injector? with finer atomization along comes leaner allowable mixtures as you pointed out. A water injection worked on the old jap airplanes too.

      Sounds like you need to drop the ecu for a programmable one. Possibly a laptop.
      Excuse me, I farted.


      • #4
        Dave I would love to program my own "mix" but there would be much expense and this is a low budget operation thats trying to achieve maximum bang for the buck, I will have a potentiometer and maybe a few preset modes at best but in general it will be the on board factory unit that makes all the decisions but they will be "leaner" decisions throughout the range except 3/4 to full throttle where i will either never be or shall leave alone if I can. I do remember honda's cvcc set-up they did wonders with a carburator - but my Bro's HF CRX is much better and its a fuely - just better pre-programmed controls - and fuely's automatically atomize better (good ones anyways)--- The first thing I would eliminate is the cycling between rich and lean, once I installed my fuel air ratio gauge I witnessed this continues cycling, its such a waste and after checking into some oxygen sensor sites I found out what its for, its to keep the Cat alive and operating in its proper heat range, all for emissions, Yup - its ok to burn twice the amount of fuel as long as the parts per million are lower and meet regs. forget the fact that there's almost twice the volume of parts per million
        Water injection is another money consumer for me and also has setbacks in the winter, I dont want to if i dont have to, I really dont know how much farther I will go after this next attempt. I got a 1,500 mile road trip coming up this fall and would like to get something dialed in before then.
        I have the two most important gauges and am piecing things together as I go - step by step. the system is going to have to remain very practical or i dont want it on -- I will have a removable recessed knob on the potentiometer that I can re-set to stock, that way I can still have other people drive my car.

        Edit; i really believe that the next phase for auto manufacturers is to incorporate an exhaust pyrometer -- not for a gauge mind you but to tie into the ECU, and it should work hand in hand with the Oxy sensor when it comes to mixture control, I also believe that the main thing holding this back is emissions as better economy does not always follow suite --- perhaps they could at least have a nice compromise.
        Last edited by A.K. Boomer; 06-11-2008, 06:26 PM.


        • #5
          In aviation the anti-detonation injection was actually a water/methanol mixture. The methanol was of course used for its anti-freeze properties. I have some brief experience with ADI (as we called it) on R-2800 Pratts. It worked pretty well when we couldn't get 115/145 octane avgas.

          (I don't think that grade of fuel has been available for a long time, unless maybe the warbird folks have a special supply)

          You'll need a flight engineer to keep track of the variables on the highway, or a good fuel injection program on the laptop.

          Sounds like the only thing left would be reducing the drag coefficient of the car if possible. How much of a batmobile look do you want?


          • #6
            Boomer, since the O2 sensors control the injector pulse rate can you control the output of the sensor to make the computer think the engine is rich and slow the injector pulse rate?

            Have you looked into the aftermarket reprogramers the change the program in your cars computer?
            It's only ink and paper


            • #7
              Yes Carld i believe this is where im going to have to make the change, Iv ran a pair of wires from the ambient temp sensors connector to inside of the cab, had the sensor mounted directly in my heater/AC vent and ran through the entire range from burn your fingers hot to freeze them off -- I really could not detect any noticeable mixture or EGT change --- my idea of changing the TPS is out because it also controls FI shut off and other functions - coolant temp sensor manipulation is out of the question as this would not benefit and could go the opposite way depending on the computers design --- If i was the programmer I would want to lean till normal operating temp -- but -- if it surpassed then I would want to re-richen the brew for cooling - I dont like it - i want to leave it alone, I dont have an air-flow meter - I do have a map sensor BUT -- I cannot get an ohms reading on it, I dont know how it works.

              So far the OXY sensor makes the most sense, And it is the most dominant sensor BUT - my luck has it that I have to come up with more volts to trick the computer into thinking too-rich, it would have been nice just to install a variable resistor between and bog down the volts -- but now Iv got to add more and im not a electronics guy, One of the theorys im kicking around is installing another, by having two I can wire them parallel, at first this might not seem to make sense BUT - if I keep one down stream it will catch the rich/lean cycle from the computer at a slightly different time, perhaps with the help of diodes I can then take the best of both spikes and also the highest of the highest low, maybe I wouldnt even need diodes? Or use oxy sensor 2 to charge a small cap? then it will medium out the low on the other sensor? HMMMMMMMMMMM
              As you can see --- Its electronics and I dont have it together at all here and am open to any useful suggestions, please help me turn my engine into a pile of molten gooo
              Last edited by A.K. Boomer; 06-11-2008, 06:56 PM.


              • #8
                Originally posted by Greg Q

                You'll need a flight engineer to keep track of the variables on the highway, or a good fuel injection program on the laptop.
                I hope not -- i may be in for a surprise but Iv got plenty of elbow room - My EGT's are 1175 cruising at 65mph on the flats, I should be able to induce a leaner mode and let the computer do the rest, when im really going for it I will have two fingers on the pot. almost always and will then manually control Mix/temps to get much closer to where i dare, where i dare will be data from many sources and also looking at my own cars max temps in its stock form, iv seen 1450 so far pulling 8 mile hill full throttle 5,000 rpms.
                Sounds like the only thing left would be reducing the drag coefficient of the car if possible. How much of a batmobile look do you want?
                my cars CD is .32, its not great but not too shabby, I dont want a batmobile look.


                • #9
                  Your best bet would be a resitor on the O2 sensors, but you also must keep the resitance in the factory spec or the ecm will detect a fault and run in a limp mode that will be rich. Reprograming a toyota ecu with anything other than the factory specs will be next to impossible. Toyota is well know for ecm's that are tamperproof.


                  • #10
                    Thanks Rookie, ( I think ) There will be a way and it might take getting many components involved, all I know is this, all these sensors are there for a reason, I also know what you mentioned in that if things get "off program" then the ECU will go into an extra rich failsafe limp mode, but I also have the ability to make the computer think its at 12,000 feet with more manifold vacuum than there really is and an ambiant temp thats much higher, then all the sudden the elbow room of the OXY sensor tricking the computer becomes much more without it going into failsafe.

                    Damn, I was hoping for some guru to come on here and say - heres what you need to do, tear out your ECU and go to resistor #486 and remove, install in its place two wires, run wires externally to radio shack poteniometer part #12675-333 have a nice day and hope all is good - any probs or questions please feel free to PM me.


                    • #11
                      LOL Boomer worker for toyota for 5 years, their ecu's are hard to trick. The new one monitor so much and have such tight specs its crazy. I have seen piggyback ecm's for extreme racing but they were for more fuel not less. I saw one unit that controlled the injectors past the ecm can't remember who made it though. It had fuel curves programmed via laptop and used the tps signal to control fuel. Also one thing to beware of is state emissions checks. Modifications may make you car fail on the equipment inspection even though it runs better.


                      • #12
                        Originally posted by Rookie machinist
                        Modifications may make you car fail on the equipment inspection even though it runs better.

                        This can be a real problem, even if the engine meets all smog spec’s it could fail a visual inspection. This has been known to happen. However around here an emission check, after they spent millions of dollars installing dynamometers, now just consists of plugging in to the CPU and looking for error codes.

                        With your two new meters you are on the right track.
                        You might want to check out this forum for more ideas.

                        It is a bunch of hands-on guys trying different mileage tricks.


                        • #13
                          An ECU is an ECU -- I dont care who's the manufacturer --- its totally reliant on sensor input --- if i have to flip a couple of resistance toggles and then ramp up a potentiometer so be it -- it will be tricked and it will be in the area's where i need it, (granted I may not be able to achieve "phase III" with it)
                          the thing is is its not my cup of tea and will most likely take me ten times the amount of time to get it where i want it.
                          No worries about emissions as we dont have testing in CC.
                          Last edited by A.K. Boomer; 06-11-2008, 11:40 PM.


                          • #14
                            Thanks Mad, im off to see what they can add.