I posted before about this awhile back and still have not solved it (I have been busy and the envoy has sat awhile) but I have a couple of updates and wanted to see if there are any fresh ideas. I saw another poster is currently having the exact same issue as me so having a solution would be nice for future reference.
4.2L 2006 Envoy XL
Essentially, this problem only happens in cold weather. The problem started last winter and since it had the issue daily I stopped driving it. When it got warmer I drove the envoy a bit during the summer (~6,000 miles) and it did not happen even once. Fast forward to this winter and it is a daily problem again. When you start the car, it starts up then immediately dies. If you try to restart it without waiting around 20 seconds it will not even crank, just one audible click. It acts as if it has a dead battery. After waiting 20 seconds, it will crank again and typically run a little longer, then stall and die after 1-3 minutes. It continues this behavior (waiting 20 seconds to start then stalling again) until the engine is up to temperature. Once the engine is up to temperature, it is as if the problem does not exist, the car runs fine all day. It does not stall again at all until the next time it has sat and gotten cold.
CE codes are:
P0014 - B camshaft position - timing over-advanced or system performance bank 1.
P0017 Crankshaft position - camshaft position correlation bank 1 sensor B.
P0171 System too lean bank 1.
P0601 Internal control module memory checksum error.
P0496 - Evaporation emission system high purge flow. (I suspect this one will be gone since I changed the valve)
Today I finally got around to changing the purge valve, It has had a problem with it for awhile and I crossed my fingers that may be it but no cigar, although it does seem to maybe stall less since changing it. I have a new ignition switch laying around I am going to throw on but I do not see how this could be the problem.
What are your guys thoughts? My gut is that it is not the fuel pump because I can hear it priming at accessory power and after driving ~6,000 miles this summer, if that was the issue I feel it would have shown other signs or quit all together by now.
4.2L 2006 Envoy XL
Essentially, this problem only happens in cold weather. The problem started last winter and since it had the issue daily I stopped driving it. When it got warmer I drove the envoy a bit during the summer (~6,000 miles) and it did not happen even once. Fast forward to this winter and it is a daily problem again. When you start the car, it starts up then immediately dies. If you try to restart it without waiting around 20 seconds it will not even crank, just one audible click. It acts as if it has a dead battery. After waiting 20 seconds, it will crank again and typically run a little longer, then stall and die after 1-3 minutes. It continues this behavior (waiting 20 seconds to start then stalling again) until the engine is up to temperature. Once the engine is up to temperature, it is as if the problem does not exist, the car runs fine all day. It does not stall again at all until the next time it has sat and gotten cold.
CE codes are:
P0014 - B camshaft position - timing over-advanced or system performance bank 1.
P0017 Crankshaft position - camshaft position correlation bank 1 sensor B.
P0171 System too lean bank 1.
P0601 Internal control module memory checksum error.
P0496 - Evaporation emission system high purge flow. (I suspect this one will be gone since I changed the valve)
Today I finally got around to changing the purge valve, It has had a problem with it for awhile and I crossed my fingers that may be it but no cigar, although it does seem to maybe stall less since changing it. I have a new ignition switch laying around I am going to throw on but I do not see how this could be the problem.
What are your guys thoughts? My gut is that it is not the fuel pump because I can hear it priming at accessory power and after driving ~6,000 miles this summer, if that was the issue I feel it would have shown other signs or quit all together by now.
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