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Did something stupid, now P1171 and P302 misfire even with new coil V70-XC70 1999

I'm a little embarrassed to admit this but tonight on the way home, I was tempted by a long stretch of empty highway in front of me and hit the gas in my '99 T5. Before I knew it, I hit 110 mph and felt the fuel cutoff kick in. At the same instant, my CEL started flashing, then went solid, and it was clear I was missing a cylinder.

Pulled over, and showed P302 I think, code for #2 misfire. Limped home, swapped in a new coil, and erased code. Started the car, and it still runs with a misfire. Reading back the codes again shows a pending P302 and now a P1171 "Long Term Fuel Trim (Upper Limit).

I've read about 1171 being the MAF, but I'm wondering if I've messed something up by hitting the governor and cutting off the fuel. I'm also lost as to why the car would continue to misfire with a new coil.

I'm trying to determine what my next steps should be. Can I disconnect the battery and force the computer to relearn fuel curves?

I don't want to think about burned valves, although a compression check has crossed my mind. I'm hoping the P1171 code indicates something beyond just a dead cylinder; something easy.

Any advice as to what's next?








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    Did something stupid, now P1171 and P302 misfire even with new coil V70-XC70 1999

    Self verified this morning with the worst of news.

    0 psi in cylinder 2 dry and wet. I guess I burned a valve...damn.








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      Did something stupid, now P1171 and P302 misfire even with new coil V70-XC70 1999

      What you did was not stupid, except in the eyes of the law. These are high revving engines and need to have the carbon 'cleaned out' once in a while. Besides smiling to yourself, patting the dash and saying, 'good girl.'

      You just hastened a problem that was already there. You could have saved yourself a bit of money by swapping the coil to another cylinder before putting a new one on, unless it was already sitting on the shelf.

      I wonder if you are using copper plugs? Some of the iridium or platinum plugs with multiple prongs have a tendency to loose a prong, which then can get trapped between the valve and valve seat.

      Klaus
      --
      My advice is free, so you got what you paid for...








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        Did something stupid, now P1171 and P302 misfire even with new coil V70-XC70 1999

        I've been thinking about the situation. The fuel cut out at about 4000 rpm. I routinely shift at that level, and regularly let the car go even higher after hearing that revving on these engines is good for them. Funny that it decided this moment was the failure moment given how many times it sees 4000 normally.

        Coil was sitting on my shelf, I've kept an extra around and replaced when necessary so I'm not out that part.

        I use only Volvo copper plugs, and an inspection of each showed no missing tips, although cylinder 2 was understandably fuel fouled.








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          Did something stupid, now P1171 and P302 misfire even with new coil V70-XC70 1999

          Fuel isn't supposed to cut out until you approach red line, not at 4000rpm. That is when the valve let go, for what ever reason. It could even be a broken valve spring?

          I know your history on the Brickboard, and you do not abuse your cars. Valves do break, not frequently but enough to give headaches to a couple of dozen owners - just on the Brickboard.

          I would start looking into replacing the head rather than getting a whole engine. There are at least 2 companies in the US that supply reconditioned heads - all new valves, seats, seals, etc. It is expensive, but so is the labor for replacing an engine. A junk yard head is a gamble and requires the same amount of labor.

          You might want to consider just unplugging the injector for #2, leave the plug and coil connected, and you can still hobble around. It will actually cruise fine on the straight and level.

          Klaus
          --
          My advice is free, so you got what you paid for...








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            Did something stupid, now P1171 and P302 misfire even with new coil V70-XC70 1999

            Thanks for the advice Klaus, the 4K cutoff did seem aggressive. In hind sight it makes sense, because if the valve gave at 4K, at that speed the reduced power would have felt like a fuel cut off.

            Right now I'm debating on either parting the car out or finding a way to get a reconditioned head and put it on myself. Shop labor on this job is more than the car is worth, although I'm not too keen on trying to install a head myself either.

            For now I'll be commuting in my 140.








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              Did something stupid, now P1171 and P302 misfire even with new coil V70-XC70 1999

              Repairman Jack just replaced his head on a T5 white block. Email him and ask him how it was. It is a 3 day job at home, unless you do it the way Jack did it and then it was 10 days! Plus he can give you some cost estimates regarding bolts, etc.

              Klaus
              --
              My advice is free, so you got what you paid for...







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