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  • Another idle issue!!!

    Ok, I know there are lots of threads on idle issues but I couldn't find one for my particular idle problem.

    My idle sometimes hangs up! It sometimes idle perfectly on 750 and then it goes up to like 1500 and stays there. I restart the car again and it either stays at 1500 or again comes down to 750.

    My mechanic just cleaned the ICV and the intake manifold gasket (recent) has been upgraded to M5 gasket which is permanent fix.

    While the engine was running, I pulled back the throttle as much as possible from engine compartment and so the problem should not be the throttle cable.
    In addition, the ECU has been remanufactured and there is no burned up ic or transistor that a faulty ICV can cause.

    My guess? Bad ICV since the car has 230k miles so the ICV could be original.

    I wanted to know what you guys have to say about it before I spend money on wrong part because my car is almost mechanically perfect and I have already spend lots of $$$ to make sure of that!

    As always, thanking you in advance for your inputs
    sigpic
    1989 M3 Cabriolet "Reproduction" #787th?? :-)

  • #2
    idle

    Hello Vasbro:
    Check the TPS Throttle Position Switch.

    Chicco

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    • #3
      I had a similar issue that turned out to be my TPS. Turned out to be a fault with the connector of some sort which no amount of cleaning could solve.

      If you unplug the TPS, does it go to the same rpm?

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      • #4
        Originally posted by Chicco View Post
        Hello Vasbro:
        Check the TPS Throttle Position Switch.

        Chicco
        Replace the TPS Throttle Position switch.

        (Fixed) :cheer2:
        Mark Williams
        Dallas, TX

        Nothing says "welcome to the neighborhood" like a search... oh wait... looks like they are all gone! :rastajake:

        sigpic

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        • #5
          Thanks guys. I did not think about the TPS. I just cleaned the ICV. I will do so just as soon as I get a chance.
          Happy New Year everybody!!!
          sigpic
          1989 M3 Cabriolet "Reproduction" #787th?? :-)

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          • #6
            BTW: where is the Throttle Position switch so I unplug and see test it out?
            Also, does anybody know the part number for it? I tried realoem but I couldn't find it.
            Thanks
            sigpic
            1989 M3 Cabriolet "Reproduction" #787th?? :-)

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            • #7
              Here's a photo with the TPS circled. It has a 3 pin connector that you can unplug most easily by standing on the passenger side of the car, reaching across the engine, and pulling towards yourself (make sure to push in the little wire retention thingy). Be careful of the fan if the engine is running!

              Dominic

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              • #8
                Dominic to rescue again! Thanks bud. You helped me with the burned transistors in the ECU too when the faulty ICV blew them!
                Anyway, after inspecting the TPS, I noticed a small screw and adjustment rail which shows the TPS can be adjusted.
                Do you know how to adjust the TPS or how to find out whether or not it is adjusted correctly?

                Thanks again
                sigpic
                1989 M3 Cabriolet "Reproduction" #787th?? :-)

                Comment


                • #9
                  OK. I disconected the TPS while the engine was running and the idle went up a little. It also "ticked" when I touch the throttle (engine off).
                  I did read in one of the idle issue threads that checking it with multimeter is not a guarantee that the TPS is ok.
                  I guess I better replace it just to make sure. It is cheap enough.
                  sigpic
                  1989 M3 Cabriolet "Reproduction" #787th?? :-)

                  Comment

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