myribitsbroke Posted February 10, 2013 Share Posted February 10, 2013 2007 Forester 4-cyl manual NACEL and flashing cruise came on, figured it was because it was overduefor an oil change. Off and on, but most of the time on. Went off whenchanged the oil but came back a day or two later. Suddenly begins to runvery rough and CEL begins to flash on way home.Codes:p0420 (cat efficiency low)P0301 (cyl 1 misfire)P0302 (cyl 2 misfire)and the MIL readings:MisfireFuelCompCatEvapO2 SensorO2 HTREGRquite a list. where to start? are some of these codes being thrown onaccount of the more serious codes (ie misfire causing o2 sensor readingto be funky, etc) Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted February 10, 2013 Share Posted February 10, 2013 Those are emissions monitors that are set as part of the emissions testing readiness checks. Nothing to worry about there. P0420 is probably on because of the misfires. Probably just needs new spark plugs. How many miles on the engine, and when were the plugs changed last, if they've ever been changed? Quote Link to comment Share on other sites More sharing options...
myribitsbroke Posted February 10, 2013 Author Share Posted February 10, 2013 the engine has about 128k bought it in august with 115k not sure if/when last time plugs were changed but will start there. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted February 11, 2013 Share Posted February 11, 2013 Yeah, start with NGK plugs, and either Subaru or NGK spark plug wires if it isnt coil-on-plug. Might do some other basic tune-up stuff too like fuel and air filters and change the PCV valve. Quote Link to comment Share on other sites More sharing options...
myribitsbroke Posted February 12, 2013 Author Share Posted February 12, 2013 put new spark plugs in today. the old ones didn't look that bad although the passenger side rear plug (sry, i'm new to subarus, don't know which cylinder that is) had a little bit of oil on it. the gap didn't look noticeably out of spec. once installed i started the car again and it still runs like garbage. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted February 12, 2013 Share Posted February 12, 2013 That would be number 3. 3------4 1------2 Front The valve cover grommet is leaking and will need to be replaced fairly soon or it will short that spark plug and cause misfires. That could possibly be a cause of the current misfiring. Does that engine have spark plug wires or individual coils mounted directly on the plugs? Quote Link to comment Share on other sites More sharing options...
myribitsbroke Posted February 12, 2013 Author Share Posted February 12, 2013 FairTax- it has spark plug wires. i found a video that advised turning the wires almost 180 degrees before removing in order to keep the metal contact in tact so i did that. how are you sure that the valve cover grommet is leaking? Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted February 12, 2013 Share Posted February 12, 2013 That's the only source of oil in spark plug wells. If it were another leak it would make a huge mess all over the engine before getting into the plug well. Have never heard of twisting plug wires. Kinda sounds like bird to me. Swap the plug wires front to rear and see if the misfire codes follow them. Or if they look old just replace them. Quote Link to comment Share on other sites More sharing options...
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