SC stalls when warm

sd_iconoclast

Registered User
I have an '89 SC 5 speed. When warm, it will fight to idle or stall when I come to a stop. The warmer it gets, the more prone it is to stalling. It also seems more prone to stalling when I stop hard. It never stalls when it is cold.
The engine is recently rebuilt with lots of performance parts, but it did the exact same thing when it was bone stock.
I have tried adjusting the idle speed set screw and it does not seem to make a difference.
I have heard that there is a procedure to teach the ECM to idle. Is that true?
Is there a procedure to test the IAC valve or the BMAP sensor?
Any other ideas?
 
do a quick check over for vacuum leaks.

but mainly, put some new heat sink compound under the DIS. u can buy it at any computer parts store.
 
do a quick check over for vacuum leaks.

but mainly, put some new heat sink compound under the DIS. u can buy it at any computer parts store.

Thanks,
I cannot find a vacuum leak. I have tried the propane method. The car idles at about 15 psi of vacuum.
I have new heat sink compound and a new DIS as part of the rebuild.
 
...The warmer it gets, the more prone it is to stalling. It also seems more prone to stalling when I stop hard. It never stalls when it is cold.
Is there a procedure to test the IAC valve or the BMAP sensor?
Any other ideas?

DIS could be it.
BAP adjusts timing, not likely.
IAC could be working in a sluggish manner, good possiblity here.
I too would like to see a test proceedure.

swag
When it is cold the EEC is in CL, and works off default A/F ratios.
Warm, EEC is in OL, could be O2 sensors in OL, momentarily giving poor a/f read,
I read Bosch had a bad batch, and switched to NkG, from sparkplugs.com
 
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How's your fuel pressure? Believe it or not these fuel injected cars will vapor lock if the fuel pressure is too low after a hot restart. I used to have this problem in my 89 - it would stall immediately after restarting until the combined vapor/liquid trapped in the fuel lines was purged and colder fuel from the tank starting flowing. After replacing the worn out fuel pump I have never had the problem again.
 
15 hg of vac huh thats bad you got a vac leak(unless thats in gear);)

I checked again. The gauge actaully reads about 16 psi. I think that is pretty good given that 1 atmosphere is a little less than 15 psi. I always hear 15 psi as what stock cars should idle at. Am I wrong?
What should I see?
 
More info:
No codes are set in the EEC.
I have a 190 lb/hr fuel pump. I tried replacing this a while back with no luck.
It appears to me that this problem is worst when I stop hard, or when I stop going downhill. It seems much less prone to this condition when I stop going uphill.
The problem is worst when I have just disconnected the battery, as if the EEC is able to "learn" to partially overcome the problem.
Does this give any more cluues?
A bunch of people seem to have posted the same problem, but nobody posted a solution.
 
I've had the same troubles, it could be a bad;

Motor mount
Cam sensor
ECT temp sensor, the two prong one
Crank "PIP" sensor
Dis module
MAF sensor

I have replaced all these, but only the bottom three have actually caused me
problems. Hope this helps
 
I've had the same troubles, it could be a bad;

Motor mount
Cam sensor
ECT temp sensor, the two prong one
Crank "PIP" sensor
Dis module
MAF sensor

I have replaced all these, but only the bottom three have actually caused me
problems. Hope this helps

I have replaced the motor mounts with new, solid mounts.
The cam and crank sensors, and DIS were replaced as part of the rebuild and made no difference.
Is there some way I can check the MAF and ECT temp sensor?
 
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