serious misfire issue!
I have a 2007 subaru wrx AT with a stage 2 tune. Earlier this month i had a deer jump out in front of me and damage the whole front end. The body shop had my car for about 3 weeks to repair everything. They said they had someone check the motor of the car to make sure nothing was wrong with it. Anyways when i picked it up i was driving home and had no problem with it as far as feeling any power loss or anything, in fact once im driving the car theres no serious issue. Yet when i come to stop the rpms at first would fluctuate and now the car shakes and feels like its going to bog out but the rpms arent fluctuating anymore. It hasnt thrown any codes and just to be sure my check engine light worked i unplugged the MAF sensor and that threw a code so i know the check engine light works, but when i hooked my computer up to it and ran the romraider logger it shows roughness on cylinder 4 and only that cylinder. It misfires the whole time i sit at idle but never throws a code. What could cause this?
Ive replaced the spark plug and switched coil packs to see if it would follow but it still shows on cylinder 4. Ive read where an injectore could go bad or could be a compression issure, but every thread i have read about this people have had codes thrown. Could it be somethin as simple as bad gas doing this? I will say as the tank has gotten lower the shake has gotten worse. Is it possible the body shopdrove it around and then put like a gallon or 2 of the wrong gas in my car and cause this? Or would that cause all the cylinders to act like this. Any ideas would be helpful before i have to go spend the diagnostic money from subaru when i might be able to figure it out myself.