91 Lumina stalls- even tried a psychic :-)

[tmcsherr]

tblake: excellent feedback, thanks....I'm surprised, if it's that common, that there aren/t more post about it here....maybe everyone that has the problem is smart enough to know what it is without asking. Tell you what though...just for confirmation...if you happen to be talking to your friend again....would you ask him what he thinks about THIS problem? Just for confirmation? The car never starts hard....just cuts out sometimes then when restarted, wont accellerate without stumbling/dying.

Jeremy: thanks, but the ignition throws a wicked spark, even when it's acting up.

[Jeremy-WI]

The ICM has the ability to trigger a spark even without the ECM hooked up, it just goes into a default mode with 10 degree BTDC spark timing. The ECM is supposed to bypass this timing once the engine hits 400 rpms by sending 5V through a wire. It could be a solder joint inside the ICM that doesn't allow it to get the 5V signal

[tblake]

Um, ya, I might see him later tonight, or tomorrow, but for sure within a week, I will ask him, and keep you informed. You said your ignition throws a wicked spark? I would, just for the sake of arguement, drive your lumina somewhere where it is completely, 100% pitch black, and let it idle in park, get out, and just look at, DONT TOUCH, the plug wires, and make sure they arent arching over to the block anywhere. Especially watch right around where the boot meets the plug. If you see any evidence of a little arc, anything at all, replace the plug wires, and also the plugs just because I say so. There might just be a bad spot on a wire where it got hot at one time and melted, or cracked, or anything, that when a little bump in the road, or anything causes it to get close to a ground, and since electricity wants to take the quickest path with the least resistance, its gonna arc right there, and probably cut your engine out, or at least cause it to run rough. But I will defenatly ask my mechanic friend, and report back asap. Good Luck.

[tmcsherr]

Thanks, but plugs and wires have been replaced. Spark is great.

[jeffcoslacker]

Originally Posted by tmcsherr

Again, it always starts...and it always idles nicely as long as you dont give it gas...just cant accelerate.

.

I missed this statement before. That says throttle position sensor to me. You can test it with an ohmmeter (I forget what range-but you can figure it out) and check for a smooth rise and fall to the reading as you slowly sweep the throttle open and closed. Any drop-outs or fluctuations not consistant with the throttle plate's movement indicates bad TPS.

[DLHUTCHENS]

2 year ago i was online asking these same questions. Replaced every sensor the car had. Plus 2 complete tune ups. 1 year ago my mechanic took a "video" of the computer's activity while driving and discovered the computer was sending wrong information intermittently, which was causing the fuel injector's to overload 1 or more cylinders with fuel. I had the exact same symptoms you described. After replacing the main computer twice, (mechanic's mistake) The car has had no more problems at all. He used a Snap-On Tools brand computer that plugged into the car's code plug under the dash and drove it for hours before finding the problem. Apparently the symptoms are worse when it is cold outdoors. So morning drives are the best time to diagnose.
Cost me around $900.00 for two years of problems. Hope this helps cut your costs.

[jeffcoslacker]

I really feel for you guys. I have had this '97 since it was new, and have never had a day's trouble with the motor or trans, even after 115,000 miles. I have put on one serp belt, 1 water pump, (put both on as a precaution before a road trip, figured it was time) 6 spark plugs and a battery. That's it. Guess I'm overdue, huh?

[tblake]

I talked to my friend.... He said that he needs more info, and that it is very hard to diagnose a problem over the internet. He did say however that the problem could be the fuel pressure regulator. I'd say if its just a 50.00 part as he states, buy one, and replace, that can never hurt. If I were to guess right now, the more and more I think about it, the more I believe it is Ignition related. My first guess is probably the Ignition Module. But if you have already replaced it, I believe maybe the problem is computer related. Not much you can do to test for a bad computer. Also, when was the last time the fuel filter was changed? Try that. Never know, sorry I nor my friend cant be of more help. Good luck, and keep us informed.

[Kooterskkar]

Guess I'm overdue, huh?

Noooo, never say that, you jinx yourself. Hey if you take good care of it nothin should go wrong for a long time. But I hope you got some money somewhere to drop on that thing. Once you hit 100,000 miles theres that much more of a chance that something will go wrong.

[tblake]

Its a chevy, its quality, if you dont beat up on it, it will last forever.

[lefty13lefty]

It could be a O2 censor they will cause the motor to run like crap and wont let it idle right, id check that then check the throttle position sensor

[tblake]

Thats the first thing I said. What I'd do is catch the car when its running great, and just simply disconnect the O2 sensor, and then start, or attempt to start, the car. If you have the same outcome as when the car stalls out, or runs crappy, then chances are faulty O2 sensor, or a bad connetsion to it somewhere.

[Kooterskkar]

once it happens, you can go out in the morning to a perfectly cold car and have the same problem....you just have to wait until it decides to go again.

That completely rules out the O2 sensor right there. It still looks like a faulty TPS to me.

[anniette]

Originally Posted by Kooterskkar

That completely rules out the O2 sensor right there. It still looks like a faulty TPS to me.

My 93 was doing the same thing, we unplugged the overdrive sensor on the front. Ran fine after that.

[richtazz]

IF it's acting up when cold, it can't be a computer related sensor, as teh car doesn't use any of them until it goes into closed loop when the motor is warm. I still say it's a fuel pressure regulator, and its a pretty simple job. The only difficult part is getting to the two small coolant hoses on the bottom of the throttle body, other than that, its gravy, shouldn't take more than 45 minutes if thos two hoses really fight you.