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850 running rough, no start 850

Hi everyone,

I'm usually a RWD guy, but I'm trying to help my sister out with her 850. The car is a 1997 non-turbo. It was running fine for a half hour drive but when she pulled into the parking lot, it acted as if it was going to stall until she put it in park. For the drive home, it would just about stall at every stoplight unless she put it in park and it seemed to be running rough. When she got home the car sounded loud- kind of like it had an exhaust leak, but more hollow sounding. She called me so I could listen and I thought it sounded like a boat outboard motor. The next day, it started, idled a bit and quit- now it will not restart. I checked it today and pulled a couple of obd codes- P0102 and P1507. Couldn't find any vacuum leaks and unplugging the MAF did not make any difference. After doing some research, I'm looking at the fuel pump, fuel pump relay, and cam position sensor- none of those explain the noise though (unless maybe the engine is kaput- it's at 225k).

Any help or advice would be appreciated.

thanks

john








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    850 running rough, no start 850

    P1507 Idle Air Control Underspeed Error

    Hmmmm, could the IAC be a little dirty?????

    Forget the fuel pump or relay or CPS, none of these will cause a poor idle. The IAC hose could be broken also, along with the accordian section of the air hose from the cleaner to the throttle body.

    Klaus
    --
    Proud owner of a 220S. If I had more room, I would have more Volvos.








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      850 running rough, no start 850

      Still haven’t figured this out and I’m afraid my sister my have to take the car to a paid professional! Here’s what I’ve tried:

      Replaced cam position sensor
      Replaced IAC motor
      New spark plugs- old ones had 40k miles and were black & oily
      Replaced fuel filter
      Replaced fuel pump relay
      Checked for vac leaks

      Figured out that it was running loud because the exhaust broke at the cat- probably from the engine running rough & shaking.

      After each of these, it would not start. It doesn’t seem like a fuel issue, because I can hear the pump running with the key on and I’ve got pressurized fuel when I crack open the connection at the fuel rail. I read that the cylinder walls might be getting washed with fuel and lowering compression, so I decided to dump a tablespoon of oil into each of the spark plug holes and do a compression test at the same time. I got 85, 85, 95, 75, 95 at first and 165, 180, 165, 150, 170 after dumping in the oil. The car fired up and idled fine after that! I hoped that one of the things I had done fixed it and my sister drove it on her 10 mile commute for the next 2 days with no problems. On the third day, it started acting up again- the Lambda light came on and it would idle rough unless it was put in park. Eventually it stalled and would not restart.

      I was thinking about replacing the coil, plug wires, and maybe the TPS before giving up. Any other ideas?








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        850 running rough, no start 850

        +1

        A hole in the exhaust ahead of either of the O2 sensors == big trouble for the fuel computer.
        --
        1998 V70 AWD->FWD Turbo 200k+








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        850 running rough, no start 850

        If the exhaust broke just in front of the cat, that would explain a lot! The O2 sensors are expecting exhaust and getting air instead. Their readings are way off, the sensors not getting hot enought to keep clean, and the Lambda light turns on.

        Take the exhaust pipe and CAT off and bring them to a welding shop. That will fix most of the problems. Check the exhaust hangers and make sure they still support the pipe, if they rust off that will cause the crack.

        The plugs will foul from the ECU being told to enrich the gas/air mix by the O2 sensors. I suspect the plugs are completely black and the rings washed with gasoline again.

        Klaus
        --
        Praying for Cynthia Amendt, heaven bound








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          850 running rough, no start 850

          The exhaust is broken after the 1st O2 sensor, which I thought had the most impact on the fuel mixture. I was thinking the post-cat sensor was more emissions related. I suppose it would make sense that the 1st sensor might not be heating up enough if it's too near the break. I just replaced it 3 months ago- wonder if it's ruined now.

          Would it be easier to just have the exhaust repaired on the car or will they have to remove it anyway?

          thanks for the help








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            850 running rough, no start 850

            Much cheaper if YOU remove it and take it to a welder. It is quite difficult to weld around the pipe when it is still on the car, plus the battery will have to be disconnected messing up your ECU.

            Yes, you will have to disconnect the 2 O2 sensors. The front O2 sensor does all of the work, the rear one verifies that the front O2 sensor has done its job correctly.

            Klaus
            --
            Praying for Cynthia Amendt, heaven bound







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