1989 corvette idle sputter
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Heel & Toe
Joined: Aug 2018
Posts: 19
Likes: 1
1989 corvette idle sputter
I have a problem with idle on my 1989 corvette. The problem seems to present itself when the car gets hot. This is after replacing the fuel injectors, IAC, TPS, CTS, EGR, Fuel Filter etc. It will idle but throttle response is sluggish out of idle and sometimes drops all the way down to 300 and idles at a minimum of 600. The TPS is set to .51 volts, was set to .54 but when I checked it after driving it may have moved...screws are tight as they can be that attach the TPS. I do not think it is pressure regulator because we have checked pressure at the fuel rail and are getting 45 PSI with key in prestart position, haven't checked pressure while running. Car did have a hard start issue but now turns right over on first crank.
Service engine light will come on but codes don't seem to latch when jumping A and B terminals to read no codes come up. Could it be my ECM?
Can someone please give me some other advice here I am out of ideas...
Thanks!
Service engine light will come on but codes don't seem to latch when jumping A and B terminals to read no codes come up. Could it be my ECM?
Can someone please give me some other advice here I am out of ideas...
Thanks!
Last edited by acerobx; Jul 27, 2019 at 09:18 AM.
Instructor
Joined: Mar 2007
Posts: 173
Likes: 18
From: Edinburgh Midlothian
I would like to know what cause it too, my 89 does exactly the same thing, only when it is really hot, oil temperature at 230+ degf.
I was wondering if it could be fuel vaporisation as it only happens when the fuel is low and only off idle.
Never does it when the car is when been running at speed only after sitting in heavy traffic for a long time.
I think it may be the fuel vaporising in the pressure regulator, I know fuel is a different specification for summer and winter, and the vapour pressure specification is different.
I was wondering if it could be fuel vaporisation as it only happens when the fuel is low and only off idle.
Never does it when the car is when been running at speed only after sitting in heavy traffic for a long time.
I think it may be the fuel vaporising in the pressure regulator, I know fuel is a different specification for summer and winter, and the vapour pressure specification is different.
Last edited by braeburn22; Jul 27, 2019 at 11:02 AM.
Thread Starter
Heel & Toe
Joined: Aug 2018
Posts: 19
Likes: 1
I just took it down to the Chevy dealer to see my service advisor, we started it and it was OK when I got there. His advice was to take it out for a good shakedown ride so the ECM can re-learn. Took it for a nice long 50 mile drive and everything fine now. Since I replaced and adjusted everything the car needed to be driven for the ECM to relearn itself.
Its doing fine now.
Not seeing the same issue with oil temperature that you are. I would check the coolant temperature sensor first. The ECM uses that input to adjust fuel/air mixture based on engine temperature from the coolant. It is a little funky but the car is very sensitive to replacement of parts and the ECM, if not bad, will relearn when driven a good bit after changes have been made.
Its doing fine now.
Not seeing the same issue with oil temperature that you are. I would check the coolant temperature sensor first. The ECM uses that input to adjust fuel/air mixture based on engine temperature from the coolant. It is a little funky but the car is very sensitive to replacement of parts and the ECM, if not bad, will relearn when driven a good bit after changes have been made.
