Idle Problems
Thread Starter
Heel & Toe
Joined: Feb 2004
Posts: 18
Likes: 0
From: Perth WA
Idle Problems
The car starts and idles ok when it's cold but if I stop and restart after running for a while it doesn't maintain idle speed. The car will drop the revs to 400RPM and stall. I've run an injector cleaner thru a tank of gas and that seemed to make a small difference but it seems to be a problem still and I'm wondering if anybody has seenthis before???
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Assuming (hate that word) your 88 or 89 doesn't just need a good tune up-I'd check my vacumn lines first-then I'd suspect IAC, go to this website www.dvcorvettes.com/clean_air_passage.htm
Good Luck and let us know
Good Luck and let us know
Melting Slicks
Joined: Sep 2003
Posts: 3,031
Likes: 74
From: If you don't weigh in you don't wrestle Road America
I would try cleaning out your throttle body, just get some rags and a bottle of carb cleaner and go nuts. This will help with the IAC as well. if that doesn't work then I would look at the injectors. If you have a fuel pressure gauge just start the car and watch the gauge over 20 minutes if the fuel is leaking down the pressure will drop, it should stay solid though.
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Originally Posted by OzzyVette
The car starts and idles ok when it's cold but if I stop and restart after running for a while it doesn't maintain idle speed. The car will drop the revs to 400RPM and stall. I've run an injector cleaner thru a tank of gas and that seemed to make a small difference but it seems to be a problem still and I'm wondering if anybody has seenthis before???
I might bit the bullet and spend $65 for new IAC, and hope that solves it. When the Idle drops to ~400RPM, it sux 'cuz it feels like the engine will quit at any moment. I turn of AC to reduce load on engine, and put car in neutral at lights.
When the car cools down, everything goes back to normal.....up until I drive for 30 minutes or so.....
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Thread Starter
Heel & Toe
Joined: Feb 2004
Posts: 18
Likes: 0
From: Perth WA
I know this is going to sound dumb but what is an IAC???
Originally Posted by rick lambert
Assuming (hate that word) your 88 or 89 doesn't just need a good tune up-I'd check my vacumn lines first-then I'd suspect IAC, go to this website www.dvcorvettes.com/clean_air_passage.htm
Good Luck and let us know
Good Luck and let us know
Thread Starter
Heel & Toe
Joined: Feb 2004
Posts: 18
Likes: 0
From: Perth WA
Originally Posted by gbody5
Stock original injectors too?
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
IAC= Idle Air Control, the web site I posted is well worth going to and reading, especially if you're having Idle problems.Remember, our cars are 16-17 yrs. old, with alot of carbon build up, simply running carb cleaner thru it might help a little-but it probably needs a thourough cleaning
Last edited by rick lambert; Jan 6, 2005 at 09:09 AM.
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Originally Posted by OzzyVette
I know this is going to sound dumb but what is an IAC???
The IAC(idle air control) valve is an ECM voltage controlled stepper motor which should be open during idle. This should allow a small but sufficient amount of air into the intake through a TB cutout passage. The engine needs this air during idle time 'cuz the throttle plates should be closed at this time(unless someone has turned up the idle screw which is a no-no). Your IAC should be located at he base of your TB, with a 4 pin connector going to it. You may not be able to see it unless you remove the air intake duct which is attached to the front of the TB.
Intermediate
Joined: Aug 2004
Posts: 37
Likes: 0
From: California
hey ozzyvette,
I've been having the exact same symptoms with my '90. I talked to a friend today who has one and he suggested checking the EGR (exhaust gas recirculation) valve, which is located under the intake plenum. I checked my hoses and stuff and they appear to be ok. I'm thinking about ordering a new EGR and hoping for the best. I've tried all the TB and injector cleaning too but it dosen't seem to help. I also tried disconnecting the IAC valve and the idle shot way up to 2000 RPMs. Then I plugged it back in and it settled down, so I'm assuming the IAC is still functioning. Anyway, hope this helps. Good luck.
I've been having the exact same symptoms with my '90. I talked to a friend today who has one and he suggested checking the EGR (exhaust gas recirculation) valve, which is located under the intake plenum. I checked my hoses and stuff and they appear to be ok. I'm thinking about ordering a new EGR and hoping for the best. I've tried all the TB and injector cleaning too but it dosen't seem to help. I also tried disconnecting the IAC valve and the idle shot way up to 2000 RPMs. Then I plugged it back in and it settled down, so I'm assuming the IAC is still functioning. Anyway, hope this helps. Good luck.
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Originally Posted by 6speedshifty
hey ozzyvette,
I've been having the exact same symptoms with my '90. I talked to a friend today who has one and he suggested checking the EGR (exhaust gas recirculation) valve, which is located under the intake plenum. I checked my hoses and stuff and they appear to be ok. I'm thinking about ordering a new EGR and hoping for the best. I've tried all the TB and injector cleaning too but it dosen't seem to help. I also tried disconnecting the IAC valve and the idle shot way up to 2000 RPMs. Then I plugged it back in and it settled down, so I'm assuming the IAC is still functioning. Anyway, hope this helps. Good luck.
I've been having the exact same symptoms with my '90. I talked to a friend today who has one and he suggested checking the EGR (exhaust gas recirculation) valve, which is located under the intake plenum. I checked my hoses and stuff and they appear to be ok. I'm thinking about ordering a new EGR and hoping for the best. I've tried all the TB and injector cleaning too but it dosen't seem to help. I also tried disconnecting the IAC valve and the idle shot way up to 2000 RPMs. Then I plugged it back in and it settled down, so I'm assuming the IAC is still functioning. Anyway, hope this helps. Good luck.