This truck belongs to a friend and i'm not very experienced with the powerstroke engines. The truck runs extremely rough at idle and pretty much has no power. The check engine light is on and I've used three different scan tools on it and none will read the codes or even interact with the computer

I expected the communication problem to be a bad IDM, I replaced it with a reman IDM and the problem is still there. The only odd things i've noticed is that the rough running is directly linked to the check engine light, as dumb as that may sound. After unplugging the batteries, the truck will fire up with the CEL on, then the CEL goes out and the truck runs great. Then if you shut the truck off and restart it, the light stays on and it runs very rough still.

One of the generic scan tools I tried had a "Cylinder Balance Test" while trying to just get the tool to do something I tried this test and while it was locked into an eternal " preparing for test " screen, It somehow made the CEL go out and the truck ran smooth again. However, restarting the truck caused the issue to come right back.

I checked out the valve cover injector connections and they look ok, but I do have the parts and plan on replacing them.

Any ideas on this thing?

Thanks in advance

 

If it has a chip ,it may have come loose ..

 

This truck doesn't have a chip, it's more or less stock short of a full aftermarket exhaust. We also replaced the CPS on this shortly before resorting to the IDM

 

Do you have a spare PCM ?

Have you ohmed the wiring to the injectors?

 

For a '94, you might need an OBD I reader.

 

I haven't ohmed the wires to the injectors yet but i have new ones with the valve cover gasket kit i was going to replace here shortly. I did, however, find that when i disconnect the ICP sensor, the truck runs exactly the same. Would this indicate that the ICP sensor is bad, and causing it to lock into a "fail safe" mode? Any ideas on a cheap place to pick one up? Napa price i found was around $340

 

I'm thinking an entire bank is shutting down when the cel comes on. IDM will do that to protect itself. If you can get it to do it when the engine is somewhat cold then feel on the exhaust pipes and see if one side is cold. If so then you have found the side creating the issue and look closely at the valve cover gaskets connections.

 

Hi Hussler,
My father in law is having the same problem as you are describing, the passenger side is much cooler replaced valve cover gasket and repaired one connection but still has the same problem.

Thanks

 

Take the IDM out & shake it , Listen for water inside ...

 

Where will it be located on a 96 E series van

 

in the same basic place. I pulled an IDM from a van/ambulance once and it was a little different (maybe next to a win/ wipe reservoir or something) but basically in the same place

 

I will check that
Thank you

 

When I looked at the pins I couldn't see anything wrong when I was having problems. The reply I got was to LOOK AGAIN!! I used a magifine glass and sure enough, one side was burned.

 

I went through and finally replaced the valve cover gaskets and the inner wiring. There was on connector that was burnt pretty bad where it met the gasket, Though the burnt wires were for the glow plug. After all the work i fired it up and it ran smooth for about 2 seconds and then back to running really rough again.

So it has a new IDM, new valve cover gaskets / wiring to injectors, Any idea on what would cause it to run really rough and have no power if these are good?

Also, the bit the still eats at my mind is the fact that if you use a scan too that does OBD1 it won't communicate with the computer to read codes and if you try to run a "cylinder balance test" It'll start it and freeze up, but after about 30 seconds it will run fine again for quite awhile or until restarted

Talk about a nightmare, haha