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Thread: Intermittent Spark

  1. #1
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    Intermittent Spark

    86 New Yorker turbo 1 car. I have replaced the HEP, and all other ignition components with the exception of the coil. I have gone out to start it on 3 different occasions and had no spark. Two days ago I was out running errands and sitting in traffic it just shut down. I tried wiggling the HEP plugs, wires, and it fired up and I was able to get home. I thought that was the problem, so I replaced the plugs and several inches of the wiring, to no avail. I discovered that when this happens, I have a relay on the drivers fenderwell that clatters and makes weird noises, as well as a solenoid on the passenger fenderwell. I can hear the fuel pump power up, just no spark. Any thoughts? PCM or logic module perhaps? I have another PCM, but not another logic module. I would hate to start throwing parts at it, not knowing the actual cause. Thanks.

  2. #2
    Supporting Member Turbo Mopar Contributor
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    Re: Intermittent Spark

    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  3. #3
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    Re: Intermittent Spark

    I would try your spare power module. My 87 Dodge Daytona T2 car was shutting off at random times. There was no spark. I replaced the HEP and messed with the wiring and the connectors. I did not notice any clicking noises under the hood and I did not have any trouble codes. My car would start after the power module would cool off after sitting with the hood open for a while. It drove me crazy until I fixed it.

  4. #4
    Hybrid booster Turbo Mopar Contributor 85lebaront2's Avatar
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    Re: Intermittent Spark

    If you need it, I have a logic module from a 1986 Laser, T1 automatic, I also have a spare power module. Since I do not ever plan on using them they are available.

  5. #5
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    Re: Intermittent Spark

    It is not showing any codes.

    - - - Updated - - -

    85lebaront2 what would you have to get for your modules? Thanks.

  6. #6
    Hybrid booster Turbo Mopar Contributor 85lebaront2's Avatar
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    Re: Intermittent Spark

    Say $125 + shipping for the pair.

  7. #7
    Supporting Member Turbo Mopar Contributor GLHS60's Avatar
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    Re: Intermittent Spark

    They're famous for LM connection issues.

    Some guys have to unbolt the LM and leave it dangling or twisted to run.

    Its a free place to start.

    Thanks
    Randy


    There is no logical reason to call an Engine a motor.

    Randy Hicks
    86 GLHS60
    86 GLHS 373 : SOLD, but never forgotten
    89 Turbo Minivan
    83 Turbo Rampage : SOLD
    Edmonton,Alberta,Canada

  8. #8
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    Re: Intermittent Spark

    I have had this happen on the GLHS and it was the LM module connection although not every symptom you're describing. A few of the wires turned to dust when I pulled them from the pigtail. Not exaggerating. It was crazy that it was driving at all let alone the random shut downs.
    Also, the plug itself had expanded where the retaining clip went in so I transferred the wires to a new plug without the clip after repairing the pigtails. I have harness sections if it turns out to be your problem and/or you can't find one.

  9. #9
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    Re: Intermittent Spark

    Thanks guys, all of you. I just replaced the PM and it fired right up. I have yet to drive it, kind of scared to until my wife gets home. lol Don't want to get stuck out on the road without someone to save me! I will let you know how it goes.
    If I have to replace the LM, I think I will get an MP unit from Forward Motion. They are not much more expensive than a reman from RockAuto.

  10. #10
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    Re: Intermittent Spark

    Update. After replacing the PM, I have been driving the car around town, with a couple of miles on the freeway as well. Seems to run fine. The only problem I'm having, is that it wants to stall when I come to a stop. It starts right back up, but it has me gun shy to drive it very far. I had the battery disconnected for a couple of days and figured the computer was relearning. I'm curious as to how long it takes for the computer to do that?

  11. #11
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    Re: Intermittent Spark

    Whenever I've had that problem it was the speed sensor which goes back to your LM harness. Did you inspect that in your progress of changing out he PM?

  12. #12
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    Re: Intermittent Spark

    Yes, I did. Everything seemed fine.

  13. #13
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    Re: Intermittent Spark

    My 87 T1 does this at times. Mine is an AIS issue.
    The AIS seems to want to closeup when you are steady drive along for a few moments and suddenly stop. It stumbles as the AIS is OFF and the bypass flow is low. under approx 600RPM the ALT field shutdown in an attempt to regain RPM. I find if you give the throttle a pump shot, the engine will recover.
    The solution is to clean the AIS using my procedure here on this site. For my DD I need to do this every six months and it takes 10-15 minutes. I did this last Saturday btw
    http://www.turbo-mopar.com/forums/sh...7-and-older-T1
    The next thing I would suggest is to open up the AIS air bypass that is set to run the engine at 600RPM when the AIS is off as per FSM.
    I would suggest to set the bypass to 700-750 RPM.
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  14. #14
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    Re: Intermittent Spark

    Rosie, are you talking about the connector at the LM?

  15. #15
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    Re: Intermittent Spark

    Quote Originally Posted by elmor353 View Post
    Rosie, are you talking about the connector at the LM?
    Yes. Under the passenger kick panel. Not to be confused with the PCM which is driverside behind battery.

    - - - Updated - - -

    Check to see if it's one solid connector (one red one blue) or if its a connector with a plastic insert that locks the wires into place. I had a bad experience with the multi piece units.

  16. #16
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    Re: Intermittent Spark

    Okay, I pulled the LM out and looked at all the connections there. They are perfect and look like they just came from the factory. I slid the plugs on and off the connectors, hoping to make a better connection if possible. I pulled the battery and looked at the PM connectors. Some of the pins and female connectors looked crappy, so I sprayed them with degreaser and slid them back and forth together as well, before pushing the plugs into the clips. I fired up the car and let it idle while I was repairing my power window and the cooling fan came on. I know this is a normal function when the engine comes up to temperature, but this is the first time since I've owned the car, that the cooling fan has come on. Typically the temp would go up while sitting in traffic and go down once I started moving and air was passing through the radiator. I'm really hoping that the connections have been the problem. I took it out and drove it around town for a few minutes and it seems ok, but I'm still gun shy about driving it very far.

  17. #17
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    Re: Intermittent Spark

    If it happens again, pull the coolant temp sensor (on head at upper radiator hose) and see if the fan turns on. If it doesn't, start "jiggling" the wires that go to the PCM. If that doesn't do any thing, use the butt of a screw driver and tap the fan relay. In fact I would swap out all of those relays on the fender preemptively if they haven't been changed since 2009. Which most haven't been changed since 87. They get rusty on the inside and get stuck or the coil wire breaks/gets flaky.

    If you want specifics I'll grab my FSMs

    Let us know...



    Quote Originally Posted by elmor353 View Post
    Okay, I pulled the LM out and looked at all the connections there. They are perfect and look like they just came from the factory. I slid the plugs on and off the connectors, hoping to make a better connection if possible. I pulled the battery and looked at the PM connectors. Some of the pins and female connectors looked crappy, so I sprayed them with degreaser and slid them back and forth together as well, before pushing the plugs into the clips. I fired up the car and let it idle while I was repairing my power window and the cooling fan came on. I know this is a normal function when the engine comes up to temperature, but this is the first time since I've owned the car, that the cooling fan has come on. Typically the temp would go up while sitting in traffic and go down once I started moving and air was passing through the radiator. I'm really hoping that the connections have been the problem. I took it out and drove it around town for a few minutes and it seems ok, but I'm still gun shy about driving it very far.

  18. #18
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    Re: Intermittent Spark

    Thanks. I appreciate all the info and help.

  19. #19
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    Re: Intermittent Spark

    Just a quick thought... could a faulty ignition switch cause an intermittent spark issue?

  20. #20
    Supporting Member Turbo Mopar Contributor
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    Re: Intermittent Spark

    Quote Originally Posted by elmor353 View Post
    Just a quick thought... could a faulty ignition switch cause an intermittent spark issue?
    It can cause all sorts of issues, Cordes has seen more than his fair share of IGN switch issues
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

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