99 7.3L powerstroke diesel run problem – powerstrokenation ford powerstroke diesel forum gas leak chicago


Started running rough, like it was missing on two cylinders and had a loss of power. We parked it for a couple weeks out of necessity and used other vehicles, but when we went back to it we noted that the batteries were weak and didn’t have enough juice to even attempt to start the truck. The batteries were old and had been showing signs of age over months leading up, so we bought new batteries and the truck was fine. Started right up and ran fine. We thought that was odd – that it would run just fine suddenly. But, we’re new to diesel trucks, so we went with it. It behaved great for several days, so we took it on a trip across our state and back and it was fine. Parked it in the drive way when we got home and it rained. Not fine. Got about three miles from home when it felt like it was missing on two cylinders again and had little power. Limped it back home and shut it off, but when we went back to it, it would start and either run poorly like it was missing on two cylinders, or it would start and shut off with two seconds.

We replaced the cam position sensor because it was possibly the problem was cheap ($24) and easy to do. And, once eliminated, we could move on to other possibilities. The truck was the same with the new cam position sensor – would either start and run like it was missing two cylinders or start and shut off within two seconds.

We did a lot of research on these forums and came to the conclusion that it was likely either the injector driver module ( IDM) or the under valve cover wiring harness (UVCH). We replaced the UVCH because it was a cheaper investment (less than $150) than the IDM. We could not find any chafed wires on either of the UVCHs we replaced, but the truck is at 200,000 miles, so we feel good about having done that and the gaskets while there, even though we found the updated harnesses from International already installed. Still, now we can trust that’ll be in good shape for another 100,000 miles.

We took it for a test drive and it was great. We took it out later that evening, it didn’t have a working speedometer and the overdrive light was flashing (on the shift lever). Found that if we came to a near stop and stopped ever-so-slightly-hard, that the speedometer would work after that. Can consistently get it to come back and can then clear the overdrive light flashing with this technique.

We continued to run it, and it was great for about four days. Then, we had it ‘cough’ a couple times while running. Sudden drop in tach and change in engine sound and performance for fraction of a second. So we knew something was not right, but it wasn’t back to running poorly/missing like it had been before.

We thought that we’d clear the codes and see what ones came back, realizing that the VSS issue could be coincident and perhaps the truck just needs a new VSS. We tried to clear the codes and the code reader said it failed to do so. We did the tests again and the codes were still there. So… we can’t clear the codes to see what’s still going on after these repairs. Suggestions on that? It’s an Innova 3130 or something like that.

Then it rained. We got about 250 feet from the house and it went back to missing and then the engine shut off. We kept trying to restart it, but it would either run rough or shut right off. We’d just gotten the scanner as a gift, so we plugged it in and strangely, possibly coincidentally, while running the KOEO test, it allowed the truck to run long enough for us to get it back to the house.

We climbed back into the engine compartment and we found corrosion on the pins of the 42 pin connector, and we found a chafed wire on the wiring harness from the IDM to the 42-pin connector where the harness touches the valve cover on the driver’s side of the engine. We cleaned the 42-pin connector with electrical cleaner and wrapped the wiring harness to it with electrical tape and then added another 4 inches of high temp wire covering like the rest of the harness is covered in. (The chafed section was immediately above where the wire covering ends.)

We went back to driving it and it was fine for a few days, so figured that we were in good shape, but here’s where we’re at now: we’re still having the intermittent VSS issue, but we can still ‘fix’ that with our trick. Does it need a new VSS or is this part of the electrical problem we’re having? Truck runs great otherwise as long as it doesn’t rain. As soon as it rains it threatens to drop out cylinders again – does that abrupt ‘cough’ with loss of power for a fraction of a second so we know somethings wrong and we can’t trust it to keep running. Could drop back into missing on two or shutting down again. So, what I’m saying is that the problem persists.

Do we need to do more for the harness from the IDM to the 42-pin connector like take it apart and actually insulate the one bare wire itself? Did we cheat by just wrapping the whole thing in electrical tape? Is it possibly moisture in the IDM and we just need to replace that? Or is it the PCM we should be looking at now? Or is the moisture getting to wiring somewhere else? Maybe from the PCM to the IDM?

And, while I’m at it, what size o-rings go between the driver’s side valve cover and the dog house for the positive crankcase ventilation? Those on ours were pretty warped and leaking a small bit of oil. Would like to take care of that but can’t find part number or specs for those.

Thanks for any help with this you can do – hubby is rehabilitating from drunk driver taking his leg below knee in an accident, so we’re finding all this work on our truck challenging, and getting stranded is a bigger problem right now than we’d like. And, there’s not a lot of money so taking it to a shop isn’t really an option. Kinda need to do it ourselves. Any suggestions on what to do next would be very appreciated. Rain in the forecast this week… 🙂