Please help - surging/stuttering when cold - SOLVED
*EDIT* - Looks like there is actually an issue with the ECT circuit to the PCM. I've started another thread with more details regarding this.
Long post, sorry... here goes:
My '02 WS6 M6 has taken to running like crap while its cold. I noticed the problem most obviously while I was watching the car warm up in the morning about a month ago. Upon the first start in the morning, the car's temp gauge fluctuates up and down from dead cold to say 140-160*. The PCM is also obviously seeing this same reading, because the engine idles up and down according to the temp (a bit faster when it reads cold and a bit slower when it reads warm). The needle fluctuates between the two different readings, in about 1 second intervals. So the car sits there and goes, "raaaaaaaaaaah, ruuuuuuuuuuh, raaaaaaaaaaah, ruuuuuuuuuuh, raaaaaaaaaaah, ruuuuuuuuuuh" at idle in the AM until the gauge reads past the first tick mark and then all seems well. When it wants to act real shitty on me, it stutters @ 1-2k RPM for a second or two and then just all the sudden recovers and corrects itself and runs fine suddenly and mysteriously...
My mileage hasn't suffered, nor has overall performance of the car. The N2O (wet) has been used a few times since this started (after its warmed up obviously) and there has been no problem at all... other than burning up my tires...
The neighbor is a mechanic who has a basic code reader. I've gotten codes thrown for all sorts of reasons, P0128 (Coolant Temp/Thermostat failure), P0134 (HO2 voltage), P0300 (multi misfire), P0301(misfire cyl1), P0306 (misfire cyl6), P0430(drivers side catalytic failure). Unfortunately, I do not have a tool to read real time data from the car...
As for the misfires and drivers side cat failure codes - I subsequently found out that I had two spark plug wires that had worked themselves off their coil packs... I fixed that problem and then the misfire codes went away. Both plugs were on the drivers side so I figured I could have toasted the O2 sensor (when pulled it had a whiteish color to it), so thats why it was replaced.
So far I've replaced: The drivers side pre-cat O2, the temp sender (ECT), and the idle air temp (IAT).
The temp gauge fluctuating is whats killing me. I can't see how there could be ANY way that the coolant temp is actually changing that much 10 seconds after the car is started in the morning.
Does anyone know what sensors are involved with calculating the temp that the PCM uses to determine engine speed during warm up?
I so just want this fixed so I don't have to pull the nitrous out of the car and take it to the stealer (dealer) to fix it under warranty...
I'll get off the now and hopefully someone can help. Thanks for the read.
-Eagle
