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Thread: Cracking noise and missing. Tach also jumping. Help!

  1. #1
    Customized Member 81dmc's Avatar
    Join Date:  Feb 2013

    Location:  Magnolia, TX

    Posts:    527

    My VIN:    831

    Cracking noise and missing. Tach also jumping. Help!

    Could this be a bad distributer cap?

    Car wants to stall in gear (600 rpm), and I'm 40 miles from home now...

    Rodolfo

    SPEC I Stainless Exhaust, Delorean.eu Roof Box, Kenwood Double Din, Black Leather Interior, Improved Wiring, Custom Dakota Digital Instrument Cluster, QA1 Suspension, Rostra Cruise Control

  2. #2
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

    Posts:    6,902

    My VIN:    03572

    Do you have a stock ignition? I ask because I had a GM unit that needed a capacitor and it made a skip like that.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  3. #3
    Customized Member 81dmc's Avatar
    Join Date:  Feb 2013

    Location:  Magnolia, TX

    Posts:    527

    My VIN:    831

    Quote Originally Posted by Bitsyncmaster View Post
    Do you have a stock ignition? I ask because I had a GM unit that needed a capacitor and it made a skip like that.
    I have the gm unit with the capacitor you sent me...

    With further testing it actually seems like your idle ecu is malfunctioning. AC will no longer bump idle and the clicking is actually coming from the vacuum solenoid.

    Idle is randomly jumping now too, but if I unplug the ecu, it just stays low.
    Rodolfo

    SPEC I Stainless Exhaust, Delorean.eu Roof Box, Kenwood Double Din, Black Leather Interior, Improved Wiring, Custom Dakota Digital Instrument Cluster, QA1 Suspension, Rostra Cruise Control

  4. #4
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

    Posts:    6,902

    My VIN:    03572

    Quote Originally Posted by 81dmc View Post
    I have the gm unit with the capacitor you sent me...

    With further testing it actually seems like your idle ecu is malfunctioning. AC will no longer bump idle and the clicking is actually coming from the vacuum solenoid.

    Idle is randomly jumping now too, but if I unplug the ecu, it just stays low.
    At least you can bump your idle up with the curb idle screw to get home. PM me your address and I will send you another ECU and you can return the old ECU in the same box. Let me know if you have the 9 or 11 pin ECU.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  5. #5
    Administrator Ron's Avatar
    Join Date:  Jun 2011

    Location:  North GA

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    Weird noise!
    In the video, were you pinching off the line that goes to the distributor (it should be the furthest port from the electrical plug on the vacuum solenoid, iirc), or was it the feed line to the vacuum solenoid? The reason I ask is
    I don't think pinching either one should have changed anything since the vacuum solenoid should be shut and not supplying vacuum to the distributor at idle.
    Are you sure it is the vacuum solenoid causing the noise...ie not something else causing it to flutter...or maybe the vacuum advance diaphragm has a hole in it...or the plate loose?

    Just throwing out ideas...

  6. #6
    Customized Member 81dmc's Avatar
    Join Date:  Feb 2013

    Location:  Magnolia, TX

    Posts:    527

    My VIN:    831

    Went ahead and installed Dave's new ecu. Unfortunately, it did not fix my issue. I was at a loss.

    However tonight, while I was fixing a bad led tail light, I had my ignition set to run for about 30 minutes. In that time, I could hear the damn clicking noise! Turns out the clicking is coming from the idle speed motor, but also every time the idle motor clicks, the vacuum solenoid clicks open. I confirmed this by unplugging and repplugging the solenoid while the issue was occurring.

    So what could be the issue? Is it a sticking idle speed motor that causes Dave's idle ecu to reset?

    Here's a quick video while the anomaly occurred. Also, after a key cycle, it didn't happen again....

    Rodolfo

    SPEC I Stainless Exhaust, Delorean.eu Roof Box, Kenwood Double Din, Black Leather Interior, Improved Wiring, Custom Dakota Digital Instrument Cluster, QA1 Suspension, Rostra Cruise Control

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