Hi all, about a year ago I started getting random misfires on cylinder 4 on my 2002 WRX. I worked myself into a panic after reading various horror stories about burnt valves, cracked rings, etc. Fortunately for me my wife wasn't working at the time, so I borrowed her car until I could diagnose the problem. Well, before I could figure it out (because honestly, I couldn't make time), I got sent on a 6 month assignment for work. I really missed driving the WRX (her name is Betty) and the commutes to and from work in a CRV only made things worse. Well, I got back last month and finally found time to do both leakdown and compression tests. Here's the numbers:
Cylinder 1: Compression - 156 PSI...... Leakdown - 6.7%
Cylinder 2: Compression - 153 PSI...... Leakdown - 5.5%
Cylinder 3: Compression - 154 PSI...... Leakdown - 4.4%
Cylinder 4: Compression - 158 PSI...... Leakdown - 6.7%
Now I don't now about everyone else, but seeing these numbers gives me chills Pretty good for an engine with 170,xxx miles!!! And not bad for a Monday!
I've been following this list, so clearly I've got a few more things to try, but it's good to know it's not the internals:
IF YOU HAVE A MISFIRE CODE ,PLEASE READ THIS!!!
I hope if you find this after searching "cylinder 4 misfire" that it gives you hope. It's not always rings or valves!