OT: Auto repair question

[Evan]

I am getting a rough idle on my '88 Ford Ranger 2.9 liter V6 4x4. It will occasionally flash up the check engine light and then it goes out by itself. I don't have an OBD-1 code reader but I understand it is possible to read them with a voltmeter in some way.

Does anybody know how or where I can find out how? I can't seem to find any info online.

[rebelrodder]

Your best bet is to get a Hayne's or Chilton's manual for your truck. The procedure will be in there. It is fairly straight forward stuff.

I haven't been successful locating that sort of stuff on the net.

[3 Phase Lightbulb]

Is it fuel injected? If not, I'd check all of breather lines going to the air filter, and check all of the vacume lines going to the carb. If those look good, then block off the vacume lines going to the accessories because if anything leaks from the aaccessory vacume system, it might drop your intake manafold pressure and possibly cause an issue with the vacume lines going to the carb/and/or emmision related items.

If it's fuel injected, and nothing wrong with the vacume lines or sensors, get an ODB reader

[HWooldridge]

I also think it's a vacuum issue. Put your AC on max and see if the air damper engages. These are typically supplied by a small diameter hose that occasionally get cracks and pinholes, which can be enough to cause a rough idle or stumble. Like 3Phase said, eliminate any possible leaks and start reconnecting stuff.

[Dawai]

MAF sensor in the air box.. first thing I would look at. I worked on one for about a week before finding it.

I got a EFI repair book, lemme look to see if the codes can be retrieved.. GM you can put a jumper in that era and it will flash a code on the dash.

[ragold]

you can get the codes out with a paper clip
you will need a haynes book to see what they mean
if its rough idle the egr valve may just be cloged
at last somthing i know a little about
this is a great bbs
rag

[Your Old Dog]

I had that problem on a Merc and like ragold says, it turned out to be the egr valve sticking due to dirty rod after a hard acceleration. Spent over $1000.00 only finally taking it to a lincoln/merc dealer in defeat and having a 20 year old kid tell me it just has to be the egr valve! He was right. The clown that charged me $900 to replace my cam chains and carburation system was wrong, rich, but wrong.

[Carl]

I agree with those above. A vaccum line might be damaged or has fallen off somewhere. Any air that gets into the system, other than the air that is metered into the system intentionally, leans it out and makes it rough.

[Kansas_Farmer]

I just tore apart a 'tree fiddy' that wouldn't start, wouldn't idle too. It had all the signs of a stuck EGR valve (closed). The thing was, the EGR wasn't stuck. The manifold ports the egr valve uses were plugged plum full tight with carbon and whats worse, it wasn't plugged at the valve connection, it was plugged up at the head connection. The EGR system wasn't working no matter what the ECM wanted.

[Evan]

The rough idle only happens under a particular circumstance. It starts and runs fine cold. After it has mostly warmed up if you come to a stop at a light or something it will suddenly start surging and stumbling for a 10-15 seconds and then catch itself and idle perfectly. After that it is fine until it has a chance to cool off completely and is then restarted. It usually only does this once per time it is started. The ECL doesn't come on at this time but does come on randomly shortly after starting the engine when warm. Reving it up once or restarting it puts the light out. It has a new fuel filter, good plugs. It does have EFI.


It's OBD-1 and I think I found how to read it and all the codes.

http://fordfuelinjection.com/?p=13

[This message has been edited by Evan (edited 01-12-2006).]