I have a Subaru 2011 WRX sedan with a turbo. Manual transmission with about 170k miles on it. Got the thing off the car lot used and for about 800 miles it ran pretty good. It does have a K&N cold air intake on it and likely tuned because you can't really run a cold air intake on them without doing so. Started misfiring and flashing lights suddenly. Was still mostly running but got so bad I had to limp it home. Was thinking it was a bad coil. So, I went to rock auto and got NGK coils and plugs changing them all out. At first it seemed to be fixed but after about 50 miles it came back and even died a couple times. Towed it to my mechanic which has 30 years experience but on domestic cars. He did his best but after two weeks told me I needed to take it elsewhere.
Well, I knew it had a iffy ground terminal and I got to messing around with it changing it. The lights went off and it seemed perfectly fine but just to tease me it seems the thing misfired again. Some people thought it might have been tune related but after I talked to a tuner that knew a lot about a WRX he didn't think so seeing how it had been driving that good for the 800 miles I put on it. Though he did advise me to have it's tune checked out just to make sure the map was right and not just close. We talked about potential causes but at the end of the day he couldn't help me not being here and it would be too expensive to tow it to him.
It's not been on the scan tool they have to charge me but the reader is more just showing that it's misfiring with nothing to really go on. My mechanic said he believed it was doing it just a little at idle but it seems to sit there and idle fine and rev up fine. I've noticed the last time it sorta jumped up a little at 3000 rpm and then misfired once after that with a flash of the check engine light on and off. Seems to be if you let it sit it will run just a bit better but the more you run it the worse it gets.
The car parts are just way too expensive to just parts cannon the thing. I really need some help to try to narrow this down a bit. There is so many things that can cause it and so few mechanics here that know much about a WRX.
