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IDM questions / buzz test code

Discussion in '7.3L Powerstroke Diesels' started by QuercusRubra, Jan 8, 2019.

  1. QuercusRubra

    QuercusRubra Registered User

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    Quick background, there's too much to say, but...
    I can tell by feel there's a slight miss, and cct fails on 4 and 8. I replaced LOTS of things so far for various reasons, incl. rebuilt inkectors.

    Just for kicks I tried putting in a spare supposedly good rebuilt IDM that a mechanic had left over. The truck ran really badly with the spare IDM. Barely ran, I'd say.

    With my old IDM it runs OK, like always, but with a slight lurch, especially when cold.

    Now after, this swap I did a buzz test with my old IDM just for kicks and it says "cylinder #x high to low side open" for all 4 on the driver's side.

    Now, my questions: are all idm's compatible? Most of what I see on the web says yes, but I've seen at least one thing saying not.

    Then, could the IDM cause that error? Anyone know what that might be? I have new one piece VC gasket/harness new GP's, new injectors. I do have a bad GP relay atm.

    Any thoughts?

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  2. 79jasper

    79jasper Chickenhawk

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    All idm's are interchangeable.
    Dump the junk dorman uvch.
    Who's injectors and what glowplugs?

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  3. QuercusRubra

    QuercusRubra Registered User

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    Not a Doorman VCG / UVCH. I used the kit from Accurate Diesel with the wiring direct out of the inside of the VCG.

    I jectors are correct stock code from Full Force. All the same, no LL. I swapped the injectors around to rule out a problem with them and the cct fail code stayed with te cylinder not the injector

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  4. QuercusRubra

    QuercusRubra Registered User

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    Why would putting in a different IDM make my truck run badly?

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  5. 79jasper

    79jasper Chickenhawk

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    My guess would be it is a bad idm that you put in.
    Until you get known good quality motorcraft uvch, it's a guessing game.

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  6. QuercusRubra

    QuercusRubra Registered User

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    So, you don't like the Accurate Diesel valve cover gasket/harness? They made the wiring pass straight from the plug on the outside of the gasket to the glow plugs and injectors on the inside... So there's no plug on the I side to go bad or come loose. Seems good to me.
    Might turn my old VCG into a test harness. The wiring looks good.

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  7. 79jasper

    79jasper Chickenhawk

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    All I'm saying is do a search about cheap off brand uvch.

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  8. greenskeeper

    greenskeeper Full Access Member

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    water or moisture in the faulty IDM? That's the only way I've seen them fail.
     
  9. raydav

    raydav Full Access Member

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    When you recommend a Ford under valve cover harness, it would be useful to note that Ford gaskets, harness and pigtail will ruin $500.
     
  10. 79jasper

    79jasper Chickenhawk

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    Yeah, unless you want to redo multiple times. And if I recall, you're still having trouble with your cheapie "one piece upgraded design," no?

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