1992 Chevy Lumina does not want to idle intermitently

KEN HEERDT

MEMBER
1992 CHEVROLET LUMINA
6 CYL
FWD
MANUAL
93,000 MILES

I have a strong running lumina z 34 3.4 engine with a manual trans, every so often does not want to idle, have replaced many components, such as idle air control, fuel pump, altenater, batt, plugs, wires , egr valve. Most times when this happens I'll have made a short trip to the store and when I come out, the engine which normally pops right off, takes an extra crank of the starter and then will not idle, and I have to keep my foot on the throttle to keep the car running. Then on the way to the repair garage the problem resolves just as I pull into the driveway of the repair garage, and the car idles soothly. It shows no codes, and the problem may not return for another 3 weeks. During these no idle periods the car runs great above idle, no hesitation or balking. So what do you think?

4 Replies

BUDDYCRAIGG

MECHANIC
2,262 POSTS

Does it only happen after start up?
It sounds like it may be related to the purging of the evap system.

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Sunday, December 7th, 2008 AT 11:42 PM

KEN HEERDT

MEMBER
3 POSTS

Thanks for your reply Buddy. The idle problem occurs after the car has been running and I make a short stop, then re-start the car. Only once that I recall did the no idle problem show up after the car had sit for 8 hrs. Would you recomend replacing the canister purge valve solenoid? Thanks for your advice. This is my first time at this sight, after posting question, I found additional lumina questions with one similar to mine his answer was a bad connection to wiring from the AIC at the ECM, which caused his intermittant idle problem. What are your thoughts? Ken

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Tuesday, December 9th, 2008 AT 11:30 AM

BUDDYCRAIGG

MECHANIC
2,262 POSTS

I can't recommend replacing parts when dealing with an intermittent problem.
I might as well tell you to buy new wiper blades.

This is why I'm leaning towards the evap system.
A short time after you start the car. The valve opens to purge the canister.
Making a controlled vacuum leak of sorts.
The computer is expecting the leak and shuts the IAC a little bit to keep the idle from going high.

If the charcoal canister is saturated or the valve doesn't open, then the extra air doesn't get sucked in to the engine so idle drops.

That's my best guess.
I know intermittent things are frustrating. You can do something and think it's fixed only to have it happen again a week later.

Good luck

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Tuesday, December 9th, 2008 AT 12:43 PM

KEN HEERDT

MEMBER
3 POSTS

THANKS FOR YOUR ADVISE BUDDY, I'LL POST THE RESULTS WHEN I DETERMINE THE FIX, KEN

Updated 7/7/09
you have probably forgotten this one because it has taken 3 mechanics and 8 months to isloate the no idle problem. After replacing altenater, batt. Spark plugs and wire IAC, ECG, intake was cleaned and boiled, evaporater system cleaned and cked, fuel pump and gas tank replaced, fuel filter replaced, and many other cks, it still had a intermitent idle problem. Then it was determined that the computer was not acknowledging the correct idle speed, don't know how this was determined, but after replacing car computer, idle is solid, and we are happy again. Please post so others can bennifit from my experience

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Thursday, December 11th, 2008 AT 10:24 AM