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At my wits end - modded IDM and codes running issues

7K views 17 replies 7 participants last post by  smokyred 
#1 ·
uuuuugh

2000 F350 manual

Ok, I could use a little help. Its my brothers truck and Its a long story, I will give you quick run down of what's going on.

Truck starts missing bad, sounds like it is going to come apart. Can get it to repeat every time you wiggle engine harness at right valve cover. Put "clips" in uvch to hold plugs, still wiggle engine harness and it happens. Replace both VC gaskets and harnesses. Now cant get it to act up when wiggle engine harness, but still will happen on its own.

At first it has a few codes (B1352, P0470, P0478, P0603) but the main one was P1316 - do a buzz test and get P1298 - switch IDM with a known good modded IDM and no problems for a few days. Happens again same code P1316. Do buzz test, no problems found. Switch back to his original IDM but now its modded. Truck runs fine again. This time for a couple weeks. Starts acting up again. My brother seems to believe it only happen every time its raining out now?????. Pull the engine harness and check all the wires, all test with in specs, no shorts. Now here is were I am -

We have code P1316 - do buzz test get code P1668 PCM/IDM communication erros

Do buzz test again and get code P0261 Cylinder 1 injector Circuit Low and P1298 IDM Failure (because of modded IDM???)

Do buzz test again and get no codes

Do buzz test once again and get P1271 Cylinder #1 High to Low side open, P1298 IDM failure, and P1293 Injector High Side Open - bank 1

Now every time I do buzz test this is what I get. Checked all injector solenoids and then test 3.2 ohms - switch #1 and #5 solenoid and then do buzz test and no codes.

start truck and now its back to the same #### P1271, P1298, P1293.

Im not sure what to do at this point. I guess I need to pin out the harness between the PCM, IDM and engine harness but I don't know what pin numbers to test. Any Idea's or help sure would be appreciated!!!!
 
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#3 ·
Thanks, I already looked at this but for some reason, my pins are different. The 42 pin connector it shows the INJHI_L at pin 16, on this truck its at pin 11? I havn't looked at the rest of it cause I just figured it was off, but maybe its something with this truck?
 
#4 ·
hey, just wondering if u got your IDM problem fixed. I got a 99 f-350 that is doing the same thing. And like you I dont have any idea why or what is causing it. I have put two different idms in and now it will run good for 5 to 10 mins. Then go back to missing. Any info would be great.
 
#5 ·
Ok, tonight I checked four different IDM's. Three modded and one completely bone stock. I checked two of the IDM's (modded) in my brothers truck and came up with the same three codes - P1271, P1298, and P1293. Checked third IDM (modded) in a differant truck and came up with same three codes. Checked fourth IDM (stock) in yet another truck and no fault codes.

I had to do several injector Buzz test to get all three codes to come up on each IDM. I did the same on the stock and no codes came up.

For me its safe to say that codes P1271, P1298, and P1293 will come up if you mod your IDM.

Now we are going to run the truck till the next time it rains and keep our fingers crossed!!!



Chris - do you have any codes with yours or maybe give us some more information on whats its doing?
 
#6 ·
Run a bead of silicone around all the edges of the IDM. Hell just wipe silicone over the entire SOB.
 
#9 ·
See if you can borrow a PCM to swap out, otherwise I think you'll be pulling the harness out.

If you need anything give me a shout, at some point we may actually both hook at the same pull! LOL

Dave
 
#10 ·
I have a NEW engine wire harness for non-GPCM truck. Even has new relays for GP's and AIH.

Dunno if you're considering that yet, but I plugged it in trying to diagnose a problem - even though its not the right one for my truck(s). I'm not gonna try to send it back to Ed. $200 shipped if ya want it.

FWIW, I had a 1294 code (high-side open) forever, but had KOEO voltage to injectors and continuity all the way to IDM (wouldn't pass buzz test). Changed VC and harness and problem solved (I think). After swapping IDM's, PCM's, engine harness, etc, etc. My point is continuity and (low) voltage didn't mean all the parts were ok in my junk. The PCM has a limited vocabulary, the 'codes' are as close as it comes to identifying the 'problem'.

Good luck!
 
#11 ·
I got 2 codes one had to do with injector #7 circuit low input and the other somthing to do with the idm. I got a reman idm and put it in and that didnt change anything. So i sent my idm to that company and they said the glow plug circuit was fried. They sent me another reman idm and now the truck will run and idle for 5 to 10 mins then miss and run rough. I was told that it was the wiring harness under the valve cover giving me fits. But that all checked out good. I just wondering if its the reman idm thats no good. I think im going to take the truck to get a better diagnostics check at the ford garage.
 
#12 ·
Why don't you do what has been suggested to you before and check out the wiring harness yourself. All you need is a multimeter and a little bit of your time. I can guarantee you that if you take it to the dealer you will be sorry. If it runs fine for a few minutes with a new IDM and then goes back to running rough then you have a wiring issue somewhere and are cooking the IDM's.
 
#13 ·
It sure sounds like your problem is the uvch.

Change both wire harnesses - Im pretty sure this is your problem.
When you do change them take notice how much tighter the new harness plugs into the Valve cover gasket. - make sure you get the "clips" to put in the new harness plug.
 
#16 ·
It sure sounds like your problem is the uvch.

Change both wire harnesses - Im pretty sure this is your problem.

OMG don't I wish I woulda just done that A LONG TIME ago. I had all kinds of wierd sh!t going on and FINALLY swapped UVCH and VC gaskets - solved the problem. The 'old' junk ohmed out FINE, had voltage all the way to injectors and 'checked out' in every freakin way possible - but didn't work. :doh:

I did do the '$0.25 mod' to the UVCH harnesses...




Now that I think about it, this should be called the $0.50 mod, eh? LOL
 
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