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CEL, low idle, what gives?

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    CEL, low idle, what gives?

    Drove my car to work this morning and it was fine. Was about to head over to a friend's house this afternoon, when I started my car and it was dying.

    The Check Engine Light is on, and the idle is either very lopy (it goes from like 400-800 and almost stalls everytime) or steady at 500rpm, which is barely enough for it to stay alive.

    I checked the fault codes, nothing is showing. I unplugged the AFM, and the car died. I unplugged the ICV and there was no change in anything. Checked all connections, looking for any loose vacuum tubes, checked the plug wires, everything looks fine. The only known issue is a leaking heater valve, and an exhaust leak at the manifold to downpipe connection.

    The exhaust leak has been around for a while, and it is on the pipe that the O2 sensor is. But if the O2 failed, why didn't it throw a fault code? And can a bad O2 cause the above symptoms? I don't think its the O2 because wouldn't it only cause trouble once it is warmed up? This started when the car was bone cold.

    Thanks in advance.

    RISING EDGE

    Let's drive fast and have fun.

    #2
    O2 sensor has nothing to do with idle. test your TPS, my car had very similar symptoms when that was going bad. the throttle body coolant hoses were leaking onto the TPS wires and causing it to short out, I ended up disconnecting the TPS until I could fix the hoses.
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      #3
      My car did this when the oil cap was loose. Check the oil cap, oil cap gasket, and valve cover gasket, as well as all the normal places for vacuum leaks.

      "See, we're adding a little something to this month's sales contest. As you all know, first prize is a Cadillac Eldorado. Anyone wanna see second prize? Second prize is a set of steak knives. Third prize is you're fired."

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        #4
        FPR hose still plugged in?
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          #5
          duh, when you unplug the ICV, the idle should crank way up.
          some's wrong there.

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            #6
            I took the valve cover off, and while nothing seems to be out of place, when I put it back on it fixed the problem.

            RISING EDGE

            Let's drive fast and have fun.

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              #7
              Originally posted by BahnE30
              duh, when you unplug the ICV, the idle should crank way up.
              some's wrong there.
              Only early cars with the silver ICV do that. The later black ICVs are opposite.
              Adam Fogg- '88 M3

              Common sense- It's the new 'gifted'

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