IDM questions / buzz test code

QuercusRubra

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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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79jasper

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

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QuercusRubra

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

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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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79jasper

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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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QuercusRubra

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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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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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79jasper

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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.
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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greenskeeper

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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.

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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Over 22 years on my 97, I've replaced the motorcraft UVCH exactly once....well worth the price

Over 20 years on my 99, I've never replaced the motorcraft UVCH

I'd suggest replacing with motorcraft or international and practically never have to mess with it again.
 
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