see post #42, page 3
Out of curiosity, did you get your code almost immediately once you noticed the rough idle/surge?My 2008 3.7 with 165k km stumbles like that sometimes too. It even stalls sometimes when the RPM falls.
I am getting a P0411 code lately.
Is there an update for open loop idle operation? If so, that might just be it. As for the crankshaft variation relearn, would that also affect closed loop operation? Truck seems to drive fine and has a rock solid idle once the secondary air injection pump turns on (closed loop).I would take it to a GM dealer and have them update the PCM with the newest version software along with a crankshaft variation relearn procedure.
I've had the rough startup with and without the CEL on. It is fairly sporadic though.Out of curiosity, did you get your code almost immediately once you noticed the rough idle/surge?
Mine has yet to throw a code and I've filled the gas tank 7 times since the symptoms started (tank fill #4 with a full can of seafoam, tank fill #7 with a full bottle of Redline SI1). No codes yet, no codes pending/stored, CEL functions properly.
- Battery check, no problems
On another note, my battery tested fine, but measures 11.5V with the truck off. 14.3V with the truck on.
I only mention this because other posts around here find out that a weak battery is the root of their problems.
Well that's funny, guess there is a bit of a disagreement between Autozone battery testers and the source of your pictures. Either way, a voltage drop is a voltage drop. Wouldn't hurt getting another battery!
If a lead acid battery only measures 11.5-volts you have less than a 20% state of charge remaining and that might cause a cold startup issue.
You either have a major parasitic draw problem or the battery is defective.