Hello there.
I am trying to fix a car for someone, and it's one of those tricky problems:
2001 legacy, 2.5 AT.
Symptoms -
1) car misfires at idle, at random, or more frequently so while barely moving at slow speed or in reverse. The misfire is random, more like a single shake once every while, not continuous. Also happens when standing at a stoplight.
2) it also often skips at hard acceleration (at different speeds while driving) - again single shake, then goes up fine, not all the time though.
Codes: p0420, p0303
(the 0420 was there for a couple of years now with no issues).
So, p0303 - misfire on the 3rd. What I've done so far:
Did a "hot soak" by poring some seafoam into the intake.
Replaced plugs, checked wires - no visible arching, resistance appears to be normal (3 and 1 lower than 2 and 4). Replaced the coil pack (used part). Checked compression - 195 on both at passenger's side, 180 on both for driver's side.
What's next? Fuel injector? Do the symtoms somehow correspond with injector problem?
Any suggestions will be extremely helpful.
Thank you.