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Discussion Starter #1
Engine lost 4 cylinders over memorial day weekend and after a diagnosis of a bad IDM by the dealer I put a reman (reputable company - $400) IDM in and it started right up. Almost immediately I noticed an occasional hiccup and almost stall. Took a week of vacation and got home and took the truck out this weekend and had another minor couple hiccups. Started it up tonight and it became a steady miss, stumble and shut down every few minutes. When it first did this I replaced the CPS with a new one from the dealer. IPR is only a year old. No codes have been stored. Fuel pressure is where it should be. Monitored ICP pressure and IPR duty cycle and nothing strange going on there. I'm wondering if the reman IDM could be the problem?
 

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Engine lost 4 cylinders over memorial day weekend and after a diagnosis of a bad IDM by the dealer I put a reman (reputable company - $400) IDM in and it started right up. Almost immediately I noticed an occasional hiccup and almost stall. Took a week of vacation and got home and took the truck out this weekend and had another minor couple hiccups. Started it up tonight and it became a steady miss, stumble and shut down every few minutes. When it first did this I replaced the CPS with a new one from the dealer. IPR is only a year old. No codes have been stored. Fuel pressure is where it should be. Monitored ICP pressure and IPR duty cycle and nothing strange going on there. I'm wondering if the reman IDM could be the problem?
I would look into the under valve cover harness

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Discussion Starter #3
Good suggestion on the UVCH. When the IDM went out and I put in the new IDM I had pulled the valve cover off and unplugged the UVCH to check them out before having it diagnosed by the dealer. I'm guessing I may have gotten some oil on the connections. I also noticed one of the locking tabs on the external wiring connection had broken off. Perhaps it has vibrated loose enough to not make a good connection.
 

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X2 on it being something with your UVCH. They do make a replacement connection too so you can replace the one you have a broken clip on. There's also a pigtail kit if one wanted to splice a new connector into the harness but I'm not a fan of that unless your current wires at the connection are bad too and needing replaced. Age and heat make those plastic connectors brittle.

Valve Cover Harness Connector Repair Kit 94-97 - Riffraff Diesel Performance

Valve Cover Gasket Connector Pigtail 94-97
 

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Discussion Starter #5
Pulled the intake hose and checked the drivers side rear connection and it was still fully seated. Ohmed the injector pins and didn't find anything out of range compared to any other connection. Started it up cold tonight and it started fine and idled great. It was fully warm when it was missing last night. ICP and duty cycle were 550-600 and 14% while it was cold. I can pull the valve covers to see if there is a problem with the harnesses but having trouble figuring out why they wouldn't also show a problem cold.
 

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Engine vibration may be moving the bad spot in the insulation and the bad spot may not be possibly shorting out when the engine is not running.
 

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Discussion Starter #7
Update.. Took the truck into the dealer this morning. They diagnosed it as a bad IDM which is unfortunate as I had just bought and installed the remanufactured IDM a couple weeks ago when the original one died over Memorial Day weekend. Will contact the company I bought the remanufactured unit tomorrow about fixing the situation.
 
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