Mechanics

WHAT IS WRONG WITH MY ?

1991 Chevrolet Lumina • 170 miles

I have a 91 Lumina 3.1. Ity stalls after warming up and wont restart untill it cools down. I check codes and it told me MAP sensor and IAC. MAP sensor was unplugged and IAC works. I removed it and tried to start and plunger retracted. Reste computer it still tells me IAC and now it tells me code 44. I beleive that is a O2 sensor. Now is my original problem a battery issue. I know my O2 sensor is bad cause I can smell the richness of the fuel now, but was fine when problem started.I have seen alot of post about this and they have replaced everything but the car and still have this problem. Anyone know how to fix my workmobile
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Tshort66
October 22, 2011.




My 90 Lumina 3.1 was having similar problems and it ended up being 2 bad fuel injectors. You can check this by taking off the plenum and removing the electrical connectors for the injectors. On the injector itself are two metal prongs. Using an Ohm Meter touch 1 prong with the positive line and the other with the negative line. Each injector should read between 11 and 13 ohms. If it reads 7.5 to 10.5 it will cause some issues but wont necessarily make your car not run but if it reads anything less your car will stall. I had also replaced the brain or ECM. While changing the injectors I replaced all the sensors in that area and the crankshaft position sensor which is located on the back side of the block to the side and down from the oxygen sensor under the spark plug on the passenger side. I used a mirror to locate it. It is easier to remove the alternator to get to it but not necessary. Be careful if you do change this sensor as it fits tightly and is known to break apart. The new ones have metal clips but the old original ones are plastic. I replaces this sensor, the oxygen sensor, the throttle position sensor, and coolant temperature sensor. I figured if I'm taking it off I'm putting on a new one! Good luck and I hope this helps!

Tiny
Tinkergirl
Oct 26, 2011.
Ok. I have cleaned the IAC OHMed all injectors. Tested EGR, 02 sensor, temp sending unit and control sensor. Still starts fine when cold and idles great then just dies when car warms up. Got good spark and great fuel pressure. What now

Tiny
Tshort66
Oct 31, 2011.
Could it be a defaulting PCM. I sure hope not. Lol
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Tiny
Tshort66
Oct 31, 2011.
I agree. It could be your ECM/PCM. They are very easy to change but mine cost 100 + a core charge. Make sure it is this before you purchase a new one and put it in, because once you change it, you cannot return it. You also have to make sure you put the memory stick from your old one and put it into the new one if you end up having to replace it.

Tiny
Tinkergirl
Oct 31, 2011.

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