So I have a hybrid motor(2.5 Sti block/ 2.0 heads) with 90k mikes on it. I was driving back from Boston and accelerated to wot and it started to misfire and got the flashing cel. Got home pulled plugs and packs. Changed all 4 plugs and replaced the cylinder 3 and 1 packs. It was a cylinder 3 misfire code. Drove fine for a few weeks and then again at wot I had a misfire, no flashing cel though and then a slight knock. The knock got louder so I drained the oil looking for metal thinking it might be rod knock, it was clean. Less than 100 miles I drained it again and still clean. So onto the timing belt thinking it might have jumped and bent a valve. Everything was lined up like it should have been, but I changed it and all the idlers and waterpump. The knocking only happens under load, nothing if I just rev it up in the driveway. It's def coming from the motor and not the trans. Did a compression test today and #3 was 120 and the rest were 100. Any ideas before I pull the motor?
Possible bent valves?
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CoupedUpSubie
FWD-FTW
Have a leak down test done on it also. With #3 being higher then the others I wouldn't suspect a problem with that cylinder. As far as the tune, did you get it tuned at a shop or find an OTS tune? Driving to Boston and back doesn't make me think its a fuel quality problem as you probably stopped at random stations on the way.
JoshP
New member
I think you would see worse numbers from bent valves, at least more variance. Plus those numbers are all low, below the minimum spec for sure.