QuestionI have read a good many of your responses to questions, and thank you for answering questions for everyone. It is a wonderful service to everyone.
My question is in regards to my 1999 Impreza 2.5 RS (2.5 liter EJ25 SOHC) with about 82,000 miles.
I have decided it is time to get my seals replaced. The engine has been drinking oil and my tail pipe is black because of it. It spits out black smoke under hard acceleration. I know you have mentioned in other posts about the seals to replace and the other parts to replace while the engine is apart, but the other posts I saw were referring more to the DOHC engines, not the SOHC. I am not sure if there is a large difference between them as far as seals go. Could you run through the list of parts to replace when I get her 'surgery' performed?
My other question has to do with misfire codes. I have recently replaced my stock exhaust with a borla header and cat-back and a stromung cat. The stock exhaust was rusting pretty severely and the cost of an upgrade wasn't that much more. The header was the first to be replaced. As soon as it was put on, I began getting misfire codes (P301,P303) for cylinder 1 and 3, but didn't really feel any skip in the engine. I figured it was an issue with the fuel being too lean or rich, but I can't seem to duplicate it. Sometimes it happens shortly after I fill the gas tank too. And I do make sure the cap is securely tightened. I have a scanner and I check the codes each time. And it seemed strange to only occur in cylinder 1 and 3. It generally happens when I am idling, rather than under acceleration. Then I thought it may be my coil pack, but didn't really know a way to check it without replacing it. The plugs and wires are not that old. I checked the plugs on the 1&3 side and they seem ok.
Any ideas, advice, etc would be wonderful.
I thank you in advance for the info. I am sure it will help me and others who read it as well.
AnswerThe misfires may go completely unnoticed to you as they generally will happen at higher rpms and can be hard for you to detect.But this should be your primary focus as a engine that is misfiring can not only damage a catalytic convertor it also excessively pollutes Our envirnment.my first thought is maybe the header pipe isn't properly sealing at the cylinder heads.When a vehicle runs too rich you will the oil can be contaminated with fuel lowering its flash temperture and making more susceptible to burning away.I feel pretty confident that if you get the engine performing better you will decrease your oil consumption as well.Any ways when a engine burns oil out of the tailpipe as a result of a internal mechanical issue such as worn valve guides,seals or piston rings the smoke will be more of a blue color.I hope this helps you but you may have to let someone who Knows Subaru properly diagnose the misfires.And not with a scan tool.Also that year RS may have a recalled mass air flow sensor
