91 lumina, acts up one minute, then fine

[jimschue]

I have a 1991 Lumina(3.1), that has been running like a champion,, then out of the blue one night, I reversed out of a parking spot, the idle dropped and she died out. Restarted, but had to give gas to get going,,, then went on driving like a champion. The next day, i went out and drove for about a mile and the speedometer went to 0 and had a higher idle. I just kept on driving and the speedometer came back and it went back to normal. I drove some more and it happened again,, speedometer failure and had to keep the car in neutral at stoplights and rev it up so it wouldn't die. Made it to my destination, parked and when i came back it started right up like normal. Driving back home, the check engine light and the speedometer went to zero simutaneously... then came right back. Made it home, and put it in reverse and it died. The engine was hot, the radiator was cold, and the fan kicked on. It's not the thermostat and i don't think it's the water pump. I'm just baffled - any ideas?

[maxwedge]

Check engine lite went to zero means what?

[jamesslcx]

Jimschue, sounds like you may have several problems. Have you replaced the fuel filter regularly? I would check and see if any codes were set and work from there.

[jimschue]

The check engine light "came on" and the speedometer went to Zero.

And now it is running real rich and it didn't read ANY codes. It drives as long as I give it gas, as soon as I take my foot off the pedal she dies out.

[maxwedge]

The pcm usually is at fault when then speedo drops out, try firmly tapping the pcm with a screwdriver handle, see if you see any changes in engine performance.

[jeffcoslacker]

Originally Posted by maxwedge

The pcm usually is at fault when then speedo drops out, try firmly tapping the pcm with a screwdriver handle, see if you see any changes in engine performance.

Agree...sounds like something a dying computer would do. Check the wiring harness to it too, make sure it's tight and there's no water or corrosion issue happening.

[jimschue]

PCM??

I've replaced the coolent sensor and the throttle position sensor. It idles great now.. but now when i give it throttle she sputters. Where is this pcm so i can hit it w/ my sledgehammer...ha ha

[maxwedge]

Underneath the hood r/s at the fender well.

[jamesslcx]

Hello jimschue, I just remembered on my 91 when I got it it had an air pocket in the cooling system. The engine sometimes got warm but the radiator did not. Does the coolant level change sometimes? This may not be whats causing the sputtering but it's worth checking. Good Luck.

[jimschue]

I replaced the ECM. Now it's just running rich on the idle. Cruises perfect. When I let off the gas pedal it starts sputtering when the speedo hits around 30mph. It doesn't die out, just runs rough and rich. I'm going to try to replace the oxygen sensor...

[jamesslcx]

Jimschue, that might work but several sensors and other problems could cause a rich mixture too. Best of luck.

[tomj76]

Check your vacuum levels, check/clean the MAF sensor. What does the exhaust look like?

[jimschue]

ECM worked for a little while, but that wasn't the problem. Vacuum hoses next on my list : /

[jamesslcx]

Jimschue, I went through the same thing with mine, at least when you get it fixed it will be like driving a new car! Let us know how it turns out and good luck, just don't give up.