Hi,
I have a 2001 Forester that has issued P0301, P0302, P0303, P0304 codes (most frequently cyl 3 and 4 together (not in pairs of 1 and 3, 2 and 4)). In my OBD software, I get activity on O2 bank 1 sensor 2 (0-1V), but constant 0V on bank 1 sensor 1. It never moves up no matter the how long the engine runs, nor the amount of throttle applied. I replaced the sensor with a Bosch (since it was the weekend and it was the only thing AZ had) but no change. The low RPM (takeoff and idle) is where the misfire occurs, if I am above 1500 or so, no issues at all. Also replaced the fuel filter, is my next step a fuel pressure test?
I have oem parts coming for a valve cover seal job, and will replace plugs, wires, and grommets/boots together, but don't think this is part of the misfire.
Any ideas? Thanks guys.