My 2004 Grand Prix (GT2, non-supercharged) has a cold-weather stalling problem. The car has 170k miles on it. The fuel filter is about 2 years old, fuel pump is 1 year old, and the MAP and MAF sensors are both newer as well.
This problem only happens when it is COLD outside (like 15 F or colder). The car starts fine, and then completely stalls after about 5 minutes of driving. The car will crank, but not restart for about 5 minutes. After it does restart, it runs fine.
The CEL does not turn on, and no codes are stored. I bought a BlueTooth OBDII scanner to watch various sensor readings while driving, and was able to replicate the stalling today with the scanner turned on. When it stalled, the MAF reading went to almost zero (makes sense betcause the engine was not running), but the throttle position did keep going up and down as I operated the throttle. The engine RPM would should about 200 RPM when I was cranking the engine, and it wasn't starting. This leads me to believe that it has either a fuel or ignition problem, and that the crankshaft position sensor and electronic throttle are fine (otherwise it would show 0 RPM while cranking, and the throttle position would not have been moving).
I could hear the fuel pump priming when I turned on they key, but the car would not start. A fuel filter problem would seem odd, because I don't see it causing a complete stall. However, I'll replace it this weekend anyway.
Any other problems that anyone can think of? Again, this only happens when it is COLD out - the car ran fine when it was 35 degrees the other day. Are there any other sensors, fuel, or ignition components that could be affected by the cold like this?
