Hello! I am hoping someone can give me some help bc these issues are driving me crzy. I had a GPR short, which in turn melted the plug that inserts into the valve cover gasket on the driver's side. Changed the GPR changed the gasket, changed the plug. Put it all back together and started the truck and it ran like crap w check engine light on. Ran code and got something like exhaust pressure sensor and number 8 injector low circuit. A buddy of mine told me to unplug the fuel injector and when I did she roared to life and the check engine light went off. I replaced the wiring harness to the injector and still the same issue. I next changed the IDM and let the truck idle for 30 bc the batteries were dead. After 30 minutes the truck started doing the same thing. Just happened to touch the GPR after this and it was scolding hot. Also noticed there was no buzzing sound when I went to start engine. Replaced GPR and heard buzzing started truck still had same problem w #8 injector plugged in. Unplugged it and she ran fine. Noticed the GPR was extremely hot again and not buzzing anymore. I am banging my head here. Any suggestions?

 

The GPR gets pretty hot when first starting the truck. Each glow plug draws about 8 amps per plug or 32 amps per bank. That's 64 amps total. I would start by checking the actual resistance on each glow plug. If you unplug the 5 pin harness on the heads the outside two pins go to the glow plugs. Using engine as a ground each glow plug should measure about 1.5 ohms.

On the issue where unplugging #8 injector the truck comes alive I suspect something is wrong in that area and the IDM is shutting down that bank. If you were rewiring the harness in that area I certainly would double check all your wiring making sure you did not cross connect something. As mentioned above the outer 2 pins are glow plugs, the next two pins in are injectors and the center pin is injector ground.

In any case I bump you up and see if anyone else has additional thoughts.

 

I'd start by just disconnecting the power source from the GPR. You can get by without it during the summer. Then figure out if you've damaged the pass thru connector at the valve cover gasket or the wiring harness to the injectors.

If you unplug an injector, the engine light should come on, not go off. When you replaced the wiring to the injector, did you replace the portion under the valve cover, or the wiring between the 42 pin connector and the valve cover? Or are you talking about unplugging the glow plug?

 

Ok spent another frustrating afternoon w this thing. As far as the GPR goes tested that and found that power was being supplied continuously to the post where the glow plug connects. So I went to CarQuest bought another relay which tests fine. Hopefully that issue solved.

As far as the injector goes. So far I have replaced the valve cover gasket, the pigtail that plugs into the outside of the valve cover. I also changed the harness that goes from the glow plug and fuel injector and plugs into the inside of the valve cover gasket. When I start the truck w the fuel injector unplugged and the glow plug plugged up it runs perfect, as soon as I connect that fuel injector to number 8 the engine light comes on and that side shuts down. I tried the quarter trick today on the the front plug and that didn't help either. I even switched the wires around on the #8 pigtail and it still did the same thing. Like I said I plugged another IDM up yesterday that a buddy let me borrow and it ran for 30 min great and then started acting up again. I have a feeling I ruined that IDM as well. I talked to a guy at Ford today and he seems to think the PCM is BAD??? I don't know what to think at this point. Also maybe wondering if that valve cover gasket maybe bad.

Any ideas?

 

I would double or triple check that the pigtail you put on is wired in correctly. It sounds as though the wiring may be crossed up somehow.

 

X2 on the wiring...

 

I looked at that yesterday. 2 browns on the outside go to glow plugs. The two inners are yellow and the center is orange. I switched the orange out yesterday and it did run a little better but was still acting up.

 

Any chance the two yellows are reversed? Do you have good continuity to ground from the center (orange) wire in the connector?

 

what would be a good way to test the continuity of the orange wire?

 

I would use a DVOM (Digital Volt Ohm Meter - ie. multi-meter) and put oit on the ohm setting. Test the value between the orange wire and the engine block or the - terminal on the battery. I'm not sure what IDM does with the ignition off, so if you don't get a reading with the key off, try it with the key on and the engine off (KOEO).

 

will do what kinda of reading should i get.

 

Here is a link that will help you out doing resistance checks ...

97-15A 7.3L DI Turbo Workshop Manual

Click on "I" then click on "Injector Drive circuit Operation".
Scroll down a bit and you will see the resistance checks.