QuestionHi Ray,
Many weeks ago now, I was on a trip and my CEL came on. I took it to a garage they put an ODBII reader on it and muttered something about O2 sensor AND catalytic converter.
I waited til I got home and took it to my favorite Volvo shop (not a dealer) and they came up with cyl-1 and cyl-2 misfire AND "random cyl misfires". No longer any codes for O2 or Catalytic.
I should also mention that by this time my gas mileage has dropped from approx 23/24 mpg to 16/7 mpg. AND strong sulfur-dioxide smells spewing from my tail-pipe. AND I should mention that, according to Volvo forums on line, one should expect (not surprisingly) rough running, hard starts, etc. NOT so with me....starts great, pulls like a champ. No bucking. There IS occasionally some major bogging down of the engine after running awhile and starting up from stop signs, etc.
It went into the shop and they replaced all the plugs, wires. Didn't replace rotor and cape because they said it looked pretty new.
CEL comes on again very soon....same codes (misfires). Same bad mileage and bad smells. Same good engine power...same occasional bogging down at stops.
I bring it back and they decide to go ahead and replace rotor and cap.
CEL comes on again very soon....same codes (misfires). Same bad mileage and bad smells. Same good engine power...same occasional bogging down at stops.
Back in shop; they replace the coil.
CEL comes on again very soon....same codes (misfires). Same bad mileage and bad smells. CEL comes on again very soon....same codes (misfires). NOW....same bad smells AND my mileage drops to between 13/14mpg. NOW, every now and then, the engine bucks. But most of the time it pulls nicely.
My guys at the shop are scratching their heads. Ideas??? Is it possible that problems with the catalytic converter initially detected could result in misfires that the diagnostics picks up before "seeing" the catalytic errors? Okay...I'll shut up now, since that's why I writing you.
Thanks in advance!!!!!
Wayne
AnswerWayne,
How is the fuel pressure? Steady, no leaking from the vacuum line to the pressure regulator? How about some internal engine problems, valves sticking due to carbon, bad valve guides. I always use original replacement cap and rotors, wires, etc is it possible that the parts you have are of low quality? Bad cat I don't think so if it were plugged you would have power loss on acceleration, possibility a rattle from broken internal cat pieces.
Sorry no short answer, that is one that will need testing and driving to feel this and take some readings while doing so. You need a shop that is willing to test and drive this car for a few days while making some tests. Last 850 or the one that I still have is fixed right now and the last thing that I did was to open the wire harness to look for broken wires and found nothing, but the car has run very well all weekend and today. Can't say what was wrong. Al the wires looked ok no bare wires that I could see.
