HELP!! Was running rough now no start.

[Dale Hackbarth]

On my '96 7.3 I have had a problem for a while now. It would run as normal and (usually a few times within 20 min. of first start up) out of the blue it would run super rough with no power and the check engine light would come on. After running rough for anywhere from 10-30 seconds the check engine light would go off and it would run as if nothing ever happened. It was a regular occurrence. Now it will not start at all. It also threw 2 DTC's. P0113 & P0472 since then I have cleaned out the EBS (exhaust back pressure sensor) (it was plugged) and it seemed to run better after that for a little while. When the problem returned I replaced the EBS (no change except it removed the P0472 DTC) than I replaced the IAT (intake air temp. sensor) (no change except it removed the P0113 DTC). I had a lift pump that was leaking so I thought maybe it was starving for fuel. I replaced it and no change. Because there are no more codes (just a P1111 which is a system pass with no DTC's available) I am stumped as to where to go next.
Any help would be great. Thanks in advance.

[justinmix]

My first guess would be something with the IDM or injector circuits, or possibly a ICP issue. I'm thinking more of a IDM issue though because a ICP issue should be logging codes. OBS trucks are prone to the valve cover gasket wiring going to the injectors burning up. I'd start with pulling all the plugs out of the valve covers and looking for burnt terminals. They tend to melt up on the outside terminals, which are for the glow plugs. If they melt enough they cause the injectors to short out and have the same symptoms you're describing.

Normally this should cause it to log a P1316, IDM codes detected. I'm surprised you don't have this code, but at the same time it depends on how good of a scanner you have. What are you using to check codes?

[Dale Hackbarth]

I am using a Superchips programmer. It's nothing too fancy. I'll check out the plugs tonight. Thanks

[erics diesel]

Have you checked the cps yet

[Dale Hackbarth]

I have not but it has crossed my mind. When it cranks I am getting an RPM reading on the tach and it is not throwing any codes to indicate the CPS. Other than the code and RPM reading I mentioned do you know of another way to check it?

[erics diesel]

It might not be totally gone yet and just gets a hiccup once in a while. I don't know of a way to check it most people just replace it and carry a spare one since they are known to have issues

[Dale Hackbarth]

Yes, over the years I have replaced it many times. That's probably what I will do. Thanks

[Dale Hackbarth]

Good call on the melted plugs outside of the valve covers. Three of them look pretty good but one is totally melted on one of the outside terminals. If that's not my problem I'm sure it is part of it. I assume on the male end it is just a matter of splicing in a new plug. On the female end (on the valve cover) how is that end replaced? Does the valve cover need to come off? How does that part of the plug get removed/replaced?

[justinmix]

More then likely you will need to replace the valve cover, the UVCH under the valve cover, and the plug on the wiring harness going into the valve cover. You can get these items thru ford or napa carries a whole after market kit that comes with all the above items.

[Dale Hackbarth]

Ha, I guess I can thank Ford for that one. They couldn't design a plug to where you don't have to replace a valve cover to replace the plug. Thanks, I'll get it done and post back as to whether or not that is the entire problem.