bansalar

The misfires occur right around when the rpm start to decrease from being cold started. I have gotten codes P0301 p0302 p0303 p0304. I did notice that it'll sometimes be random cylinders like only cylinders 1 2 and 3 misfiring and seems to be random. One thing I've noticed though is that cylinder one seems to misfire the most. Once the car is warmed up it won't misfire at idle and runs fine underload. I've been watching the roughness count through the access port and I've had the value hit about 12 at the highest. I don't always get a CEL but the AP will pick up on it. The car only has a Cobb downpipe and I was running the stage 2 93 octane tune from Cobb. I did switch to stage 1 to see if it would fix it but it didn't.

I've done the spark plugs and ignition coils. I'm planning on cleaning the camshaft sensors and taking a look at the idle air control valve. I haven't done a compression/leak down test yet.

Is there anything else I'm missing? Could it be an O2 sensor or something emissions related? Also is there anything that I can datalog to help me diagnose?

Don Clark

Diagnostics from 2011/13 US Workshop manual