I have a 97 F-350 with 358,000klms (222,450 miles). Several weeks ago at -20C I started it up like always and it ran great. White smoke for about 20 seconds and and then it cleaned up and away we went. About a two minutes in the CEL came on. I'd never seen it before. Engine ran terrible, it was missing. I warmed it up and eventually after restarting it a few times, the CEL went out and it ran fine. I made another 10 minutes and it did it all over again. I limped it home, making white smoke as I went. I did my research and sure as $#!^ the UVCH had one connector melted on the outside. This engine is a two connector UVCH. I bought a new Dorman and installed it. Truck ran poorly until I discovered I pinched the supply wires under the gasket for #4 and #6. I made the repair to the pinched wires. They were cut, soldered and shrink tubed. The engine had been plugged in and was warm. It fired up and ran great. I drove it all over town with no issues. Two days later at -1c the truck wouldn't stay running after start up and the CEL was back on. Eventually I got it to stay running poorly and I warmed it up and the CEL went out and it ran fine. Next day I pulled the harness off at the IDM and checked the resistance from the IDM to the injectors. All 8 injectors circuits were 2.9 to 3.4 ohms. I was showing codes P1272, P0270 and P0276. I swapped the 6/8 five pin injector/GP connector into the 2/4 connector and left the 2/4 connector disconnected. I ran the KOEO test and the same codes appeared. My expectation was that the 6/8 connector being connected to the 2/4 UVCH connector would have registered the 2/4 injector codes but shown as 6/8 and my 2/4 codes would have changed as the connector was completely disconnected. I removed the IDM and checked for possible water ingestion. It sounded fine. All my connectors looked OK. I was field mechanic for a CAT dealer for 17 years. I've trouble shot CATs HEUIs before. My thoughts are this;
The unchanging codes when the connectors are moved makes me lean towards the IDM.
The injectors at this age also makes me think lazy (warn out) injectors, but the ohms say if the signal is sent, it should work and it does when warm.
The truck up this point has been stellar. No loss of power, no change in fuel economy and no hard starts.
I'm looking for some experience that can help me decide if its injectors or the IDM. Thanks everyone.

 

What were the codes?

 

Do you know anyone with a 7.3 truck that you could put your IDM in to see how it performs in a different truck? If the problem follows to the other truck, the problem is probably the IDM. Just a heads up, some folks have had problems with the Doorman gaskets right out of the box, while others have run them for many miles. By looking at the results o the ohm test you ran, it seems that the gasket is good though.

 

Well, I know it's a PITA, but I recently just changed over to a SD 120 IDM. So I happen to have a spare if you need to test it with. PM if you want to work something out.

As for the gaskets, I had the same thing happen to me, the rear driver plug melted and melted the pigtail. No interior damage that I could find on the gasket, so 2hrs later, I was switched to the SD wiring with a single pigtail on each side.

 

If it were me as in the past doorman was less than stellar for me...I would be doing new top quality ford gaskets,pigtails etc before I looked I to idm. It could still be idm but I would do a good baseline to build from as these can be very temperamental. I and several others have changed over to the SD style gasket and connector as they are less failure prone historically in respect to burned up pins.

 

Thanks. The cost of a new Ford gasket is about the same as an IDM. I think the gasket is OK but I will Ohm it out on your advice. You would think if I had a short it would be more prevalent throughout the range of warm and cold. Once the truck warms up even a bit, it runs great.