Need Help!

J

JBrady5979

New member
Hey i need some help and i figured this would be the place to start. i Have a 94 Gen1 and the past couple weeks i have been having an issue that i cant pin point but have ideas of what it could be. So i was driving to work and came to a stop at a light and the truck started to seem like it was going to choke out and drop to about 400 RPMS and come back to about a grand( normal idle at a stop) and would contin. Now after a full service the problem seems to be getting worse and check engine light is on and off. But also the truck runs fine while im driving its only at a stop or at an idle in drive when the rpms drop. I am leaning towards EGR sensor and or IAT, and this is where i need Help. Am I right or wrong or both..HELP PLEASE I DONT WANT TO LOOSE MY TRUCK!!!!!!!!!!:help::flamed:
 
1st recommendation: if you have a question like this, post it to Gen 1 Lightnings - The National Lightning Owners Club Inc, not to "Times and Modifications"

2nd recommendation: before you post a question like this, read the current discussions like this one http://www.nloc.net/vbforum/gen-1-lightnings/216268-erratic-idle-wont-idle-where-start.html that might answer your question before you ask it.

3rd recommendation: if you've got a check engine light, pull the codes before you go on an easter-egg hunt and swap out perfectly good parts.
 
Appreciate the quick reply. I did run the codes got nothing the first time, got bad o2 sensor and the 3rd time vac issue. I also appreciat the links, found that thread a while back and couldn't find it when I needed it so I figured here would be a Good place for any kind of help wich i got. I'm pretty new to this site so i apologize, i didn't think I was going to get hounded by the forum police, just looking for help. Thanks hopefully ill have some additions to be qualified for this thread.
 
First thing Id do is remove and clean both the IAC valve and the TB. Iknow I know the sticker on the TB says DO NOT CLEAN but Ive done it many times.
Oil and sludge tend to build up in the IAC and on the back of teh throttle blade due to the lovely PCV system. Cleaning them will usually will fix a surgeing/hanging/dropping idle issue on most injected 5.0/5.8
 
Sorry, guess I was tired and cranky last night. It's just that there are so many things/combinations of things that can cause idle problems, and there are so many posts about fixing idle problems...

Not sure what you mean by "a full service" ... new plugs, wires, cap, rotor, air filter & fuel filter? If you've done all that, then Jim's recommendation is a good place to start.

A bad O2 sensor or EVP sensor won't cause your idle problems, but a vacuum issue will. The only "vacuum" code is 128 - "Manifold absolute pressure sensor / vacuum hose disconnected / damaged" so while you've got the throttle body off to clean, check the vacuum hose tree back there - especially the one on the MAP. If the hose is good, replace the MAP.

When you've done all that, fire her up and let us know how it goes.
 
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