Now takes over an hour to die.

902RTU

MEMBER
1990 CHEVROLET CELEBRITY
6 CYL
2WD
AUTOMATIC
95,400 MILES

Pulled the transmission electric connection and the engine stalling stopped but, after an hour or so of driving it's back. No 'check engine' and no codes. Runs great, when it's running. Something appears to be heating to a failure point and the engine dies. The next morning, it's normal again, for a while.

7 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Check and test the TCC solenoid

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Saturday, June 4th, 2011 AT 5:11 PM

902RTU

MEMBER
6 POSTS

Since it's already unplugged, I assume it's no longer a factor. The car was finally shifting down to the lowest gear and idling while stationary but, after an extended drive, resumed the 'no downshift' problems even though still unplugged. What determines the mixture setting? My starts are requiring some throttle pressure - opening the valve and allowing more air.

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Wednesday, June 15th, 2011 AT 4:20 PM

RIVERMIKERAT

MECHANIC
6,110 POSTS

Check to be sure the 'kickdown' cable is properly adjusted. Make sure the throttle position sensor is reading properly. Flush the transmission fluid, especially if it's brown or smells bad.

Fuel/air mixture settings are determined by the mass air flow sensor, o2, sensor and throttle position sensor in conjunction with engine speed sensors. Run a bottle of quality fuel system cleaner through the tank. The engine is supposed to get an extra little shot of fuel in order to help with proper acceleration. It sounds like this shot is being diminished, most likely by varnish buildup.

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Saturday, June 25th, 2011 AT 9:36 PM

902RTU

MEMBER
6 POSTS

Another wrinkle. A while ago, I had the alternator bench-checked. It was good so replaced the battery. The new battery finally discharged to the point where all I was getting was solenoid click and the check-engine light was missing. Recharged the battery and found 14.5v at the alternator and 13.4v at the battery. Is this normal or do I have an alternator wiring problem, also what is the minumum voltage required by the ECM? When the check-engine light disppears, things get a abnormal.

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Monday, June 27th, 2011 AT 3:14 PM

RIVERMIKERAT

MECHANIC
6,110 POSTS

Alternator output is considered within norms when it's between 12.8 and 14.6, give or take half a volt. Battery voltage is usually considered within norms between 11.8 and 13.2, so your reading of 13.4 is actually a little higher than normal. However, under a load test, battery voltage shouldn't drop below 10.5 volts. It doesn't sound like there's a problem with your charging system. The ECM wants voltages between the norms. Have the battery load tested. It's ability to supply the required amount of current within acceptable voltage ranges is more important than the surface charge.

What sort of accessories are installed? Stereo? GPS? Other toys? Make sure they're all fully powering down when you shut the car off for awhile. Pull the negative cable and look for a spark. It should be very tiny, almost unnoticeable. If it's quite noticeable, find what's causing the drain. Such as a short somewhere or an electronic component not being turned off properly. We had one issue recently where it turned out there was an aftermarket stereo and it had a fan attached to the back that ran constantly.