2000 Chevy Impala Can anyone help with a really tricky stal

Tiny
BUICK301
  • MEMBER
  • 2000 CHEVROLET IMPALA
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 160,000 MILES
I have a 2000 Chevy Impala with the 3.8L V6. It has nearly 160,000 miles on it but it runs strong. When it's running. The trouble is, seemingly for no reason, it stalls out. It has stalled on me at various times but usually it is when I'm slowing for a stop or under 40MPH. (Most of the time, it stalls within the first 20 minutes of driving but not always.) I've already replaced the fuel pressure regulator, the ignition module, the crank sensor, the cam sensor, the spark plug wires, the spark plugs, the fuel filter and a number of other tune up related items. I don't suspect the fuel pump because there always seems to be a strong source of fuel at the rail when I break down and I haven't stalled at highway speeds. I've cleaned the mass airflow sensor with an approved cleaning solution and examined the idle control motor which looks okay but I'm not sure how to test that under load. When the car stalls, my scanner tells me there are no engine codes or other signs that there is an engine fault. When I try to restart the car, I'm usually able to give it some gas and keep the RPMs really high while it lurches and sputters to the side of the road. I can usually do this a couple of times before I'm no longer able to force the engine to run like this. (Another indicator for me that this isn't a fuel delivery problem is the fact that I smell a lot of unburned gas when I try to restart.) Between 30 minutes and an hour later, the car will start up perfectly fine and run flawlessly for hundreds of miles or more before it suddenly dies again! Any ideas?
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Wednesday, September 1st, 2010 AT 9:52 AM

6 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
When it doesn't start, are you getting good fuel pressure and spark to the engine?
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Friday, September 3rd, 2010 AT 10:42 AM
Tiny
BUICK301
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I have to make a couple assumptions here because the car hasn't died since I've begun keeping test equipment in the trunk. I'm assuming that their is at least good enough fuel pressure to start because I pushed the needle in the schrader valve on the fuel rail and got quite a bit of fuel squirting out after it died.(I didn't use a gauge however). The exhaust stinks like unburned fuel after a few start attempts which is the other fact that makes me believe it isn't a fuel problem. As for the spark, I suppose some intermittently bad coil packs could be causing the problem (I've replaced all the other parts of the ignition system). I'm carrying a spark tester to check this out the next time it happens.

-Joe
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Friday, September 3rd, 2010 AT 3:29 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
I understand and agree on the fuel pressure. As far as a bad coil pack, it should have set an engine code. Has the check engine light ever come on?
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Friday, September 3rd, 2010 AT 11:24 PM
Tiny
BUICK301
  • MEMBER
No, there haven't been any engine codes. Someone suggested a faulty MAF sensor. What are your thoughts on that?
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Saturday, September 4th, 2010 AT 9:10 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
It could cause it too. Again, it should have set a check engine code. If you want, they make a special cleaner for the MAF. Try cleaning it to see if that helps.

Let me know.

Joe
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Sunday, September 5th, 2010 AT 11:20 PM
Tiny
TAKECHARGESARGE
  • MEMBER
Hi buick301,

This sounds so much like my 2000 Chevy Impala stalling problem. No warning lights, no codes, stalling for no reason, and able to restart and drive as if there was nothing wrong.

My problem was found to be caused by the Crankshaft Position Sensor.

I read that you have already changed the sensor, so all I can suggest is that you remove the good sensor and make sure the grooves in it are clean of debris (magnetic particles that build up during driving). Also,
I have read that there was a time when a bad batch of these sensors were put in service.

There is a max. Resistance test for this sensor, but I don't have the numbers or the procedure for it, and if it happens as a heatsoaking problem, it'll need to be heated for the test.

Good luck,

TakeChargeSarge
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Monday, September 13th, 2010 AT 12:07 AM

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