I have a 2004 Subaru WRX and a few weeks ago my check engine light came on and when I checked there were five codes, P0301, P0302, P0303, P0304, and P-0171. When I'm driving everything seems to run okay, but when I stop and let it idle it idles very rough and almost sounds like the engine is going to die, but it never has. I've read a few of the threads on here about things that can resolve the problem but so far nothing I've done has helped.
Some things that I've done so far include running several bottles of fuel injector cleaner through the gas tank, replaced the mass air flow sensor, replaced the fuel filter, and replaced all four spark plugs. When I had the spark plugs out I performed a compression test on all four cylinders and they average out to around 50 PSI which seems really low to me. I've been reading on one of the threads about misfires and it seems like the next step I should take is to replace the Cam Sensor? I've already verified that the coil packs aren't mixed up, that I have the right spark plugs and that they are gaped correctly.
Does anyone have any suggestions of what step I should take next or what the issue may be?
Some things that I've done so far include running several bottles of fuel injector cleaner through the gas tank, replaced the mass air flow sensor, replaced the fuel filter, and replaced all four spark plugs. When I had the spark plugs out I performed a compression test on all four cylinders and they average out to around 50 PSI which seems really low to me. I've been reading on one of the threads about misfires and it seems like the next step I should take is to replace the Cam Sensor? I've already verified that the coil packs aren't mixed up, that I have the right spark plugs and that they are gaped correctly.
Does anyone have any suggestions of what step I should take next or what the issue may be?