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Thread: Help with a high idle....

  1. #31
    Senior Member NckT's Avatar
    Join Date:  Jun 2011

    Location:  Yorkshire UK

    Posts:    198

    My VIN:    No. 4068

    The 'thermister' is physically located on the V coolant pipe under the inlet manifold.

    To test it, just remove the white electrical connection from the idle ecu that has 4 wires on it.

    Set your multi meter to resistance (0-100 k ohm) and connect the multi meter probes to the Black/Slate (grey colour) and the Black/Yellow cables (not the ecu itself)

    You should get approx 12k ohm at engine warm temperature.

    If you get open circuit then that's your problem. I.e. a wiring problem or connection problem.

    Good luck

    Nick
    RIP Rob van de Veer Top bloke

    I say Sir, I must be mad, one loves fixing K-Jet !

    Make sure there's plenty in the tank for the weekend chaps....

  2. #32
    Senior Member
    Join Date:  Jun 2011

    Posts:    4,807

    My VIN:    3937

    I added a thermister location photo here: http://dmctalk.org/showthread.php?10...l=1#post222057


    Sept. 81, auto, black interior

  3. #33
    Senior Member
    Join Date:  May 2011

    Posts:    605

    Quote Originally Posted by rjd2 View Post
    yes, thanks for that test. If I'm understanding correctly, I pull the 3 pin black electrical connector to the idle speed motor, bridge the middle pin(+12V), and then tap either of the left or right pins to ground. My alligator clip method is a bit janky, but I was able to do this and at least bridge the left pin to ground. It goosed the idle speed up to about 1500-ish for about 1-2 seconds, then it fell back to the ~500-ish range that it idles at with the motor disconnected. I will try to test the right pin tapped to ground, and see what it does.

    thanks for the help!

    I am wondering a bit - why would the speed drop after 1-2 seconds ?
    The idle motors that I know stay in their position, they do not close by themselves.

    I did not expect this answer.

    The goal was to find out if the idle is to high because of a mechanical problem or
    because of the ECU. I don't undestand why your car would be different.

    If it's the ECU -it could be the thermistor or simply the power stage transistor that failed ( very common).

  4. #34
    Senior Member
    Join Date:  Mar 2016

    Posts:    182

    It was suggested to "just tap" either the left or right pin to ground, so that's what I did. I just tapped a jumper wire very quicklyf from the left pin on the motor to ground; it raised the idle to ~1500 for about 2 seconds, and then it fell back to it's resting rate with the black idle speed harness DISconnected(~500 or so). If any of my testing methodolies are off here, please correct me! Thanks!

    Quote Originally Posted by Elvis View Post
    I am wondering a bit - why would the speed drop after 1-2 seconds ?
    The idle motors that I know stay in their position, they do not close by themselves.

    I did not expect this answer.

    The goal was to find out if the idle is to high because of a mechanical problem or
    because of the ECU. I don't undestand why your car would be different.

    If it's the ECU -it could be the thermistor or simply the power stage transistor that failed ( very common).

  5. #35
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

    Posts:    9,000

    My VIN:    03572

    Quote Originally Posted by rjd2 View Post
    It was suggested to "just tap" either the left or right pin to ground, so that's what I did. I just tapped a jumper wire very quicklyf from the left pin on the motor to ground; it raised the idle to ~1500 for about 2 seconds, and then it fell back to it's resting rate with the black idle speed harness DISconnected(~500 or so). If any of my testing methodolies are off here, please correct me! Thanks!
    I wonder if your idle speed motor is installed backwards. Can you post a photo of it.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  6. #36
    Senior Member
    Join Date:  Mar 2016

    Posts:    182

    Thanks. I just did this test; at resting temp, it read ~4.5k. After running the car for about one minute, it read ~2.4k. That sounds off, eh?

    Quote Originally Posted by NckT View Post
    The 'thermister' is physically located on the V coolant pipe under the inlet manifold.

    To test it, just remove the white electrical connection from the idle ecu that has 4 wires on it.

    Set your multi meter to resistance (0-100 k ohm) and connect the multi meter probes to the Black/Slate (grey colour) and the Black/Yellow cables (not the ecu itself)

    You should get approx 12k ohm at engine warm temperature.

    If you get open circuit then that's your problem. I.e. a wiring problem or connection problem.

    Good luck

    Nick

  7. #37
    Senior Member
    Join Date:  Mar 2016

    Posts:    182

    Also, I'm not sure if this matters, but in the attached pic, you will see a red wire with a fuse in line. The fuse socket was empty. With the car not running, or keys in, i seated a fuse, and the fuse blew immediately. Not sure what that means, if anything...IMG_1182.jpg

  8. #38
    Senior Member
    Join Date:  May 2011

    Posts:    605

    tapping ground on one side fully opens the valve, on the other side fully closes the valve.

    so simple.



    and that fuseholder is from the power antenna

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