I searched around and must have read 30+ threads about P0300 but very few follow ups on what the solution was. (Or maybe there were many and my fever is screwing with me.) Anyway, Monday, on the way home from work, the car suddenly surged and then the SES light started flashing. Symptoms were rough idle, engine sounded like it was struggling and it would not climb over 4000 RPMs. I plugged my bluetooth OBD II adapter in and fired up Torque. Discovered I was misfiring on cylinders 1/4 when the engine revved or loaded. Knowing that 1/4 were controlled by the same coil, I called my house and had my fiance' bring out the spare coil I had in the closet. (It came with the car)
Swapped that coil in and....still misfiring. Hmmmmm. Ok, time to swap known good coils. Then I had misfiring where I moved the coil AND 1/4. Ruh-roh. Took it to my mechanic and he quickly threw the aftermarket coil in the garbage and gave me a nasty look. The car came with 2 original coils and an aftermarket. We opened the coil and apparently the connection inside had fried and shorted out the secondary which then killed the ICM.
He SWEARS that if I buy any ignition piece OTHER than AC Delco he'll kill me. Apparently the stock stuff is so good, some tuners use them for other high HP builds. *shrug* Just what he told me. Anyway, new AC Delco ICM and Coilpack and not only does the car feel MUCH faster, I picked up about 2mpg, maybe a hair more.
I don't know if this helps anyone but I thought I would share my story. (Yah, yah, I know, cool story bro.)
Peace!
Originally Posted by darkhorizon
