Normally if one is shot so will the other.

 

I just tried pulling the 5 wire plugs off the valve covers with the truck running at idle. The 2 on drivers side killed the engine, the front on the passenger side didn't seem to make much difference the rear on pass side made a little difference.
So here is the question does the wiring or plugs on the topside of motor go bad also (the plugs look good) or is it usually the UVCH that goes bad?
Thanks RB

 

You need to OHM out the connections to the IDM and ohm out the injectors and glow plugs.

 

I have no idea how to do what you are talking about.
Is there somewhere I can get detailed instructions?
Thanks RB

 

I didn't know how to do all that, I checked the glow plugs with a test light like I found on here but I don't know how to check the IDM or the injectors.

I had some time today so I pulled the passenger side Valve Cover off to check the connections and I did not find anything that looked bad to me at all except 1 of the glow plugs had a wire that was partially bare on it.

I did notice that the gaskets and UVCH had China on them. I had these replaced a few years ago when I was too busy at work to do it myself.

How can I check the Injectors and the IDM?

 

If they say china, then they are probably dorman brand, which are known to be hit and miss on how well they work.

To ohm out the injectors, have them connected to the UVCH and VC gasket. Use a DVOM in the Ohm setting to check resistance between the center pin on the plug and the two pins on either side of the center pin. Report back with your findings.

If you have a bare GP wire, you need to replace that anyway. Go OEM on your parts, they can be purchased most affordably from riffraff diesel performance.

 

Ok I just checked them and #2 is 3.3 #4 is 3.3 #6 3.2 #8 3.3

I plan on changing the uvch and vc all out for OEM.
Thanks for the help
RB

 

Those are good. Next is to ohm the IDM connector out.

 

Thats good. How do I ohm out the IDM?
I have put 2 of these on in the last 10 yrs.

 

Measure switched ground to feed at the connector and you should be getting similar reading you had before. higher or lower means a wiring issue

 

I ckecked those all were 3.3 except #8 was 3.2
I assume that means wiring is good but the signal is not going out from the IDM?

thanks RB

 

It could mean that, but you ought to go get OEM wiring and solder the wire splices on the pigtails. You might want to look into upgrading to the SD style plugs. Its a little more work, but well worth it in my opinion. I did it to my 96, and my 97 will get the upgrade if it ever needs new UVCH, etc.

 

BY OEM wiring do you mean the wiring outside of the VC, just the pigtails or replace UVCH, gasket, and the pigtails also?

If they ohm out ok could the wiring still be the problem?
Or should I change the wiring first and then see if it fixes my problem before replacing the IDM?
What year SD would I use parts off of?

Thanks RB

 

Make sure all components are OEM. If your pig tails and gaskets are OEM and in good shape then stick with the OBS stuff.

When I had my bout with Dorman wiring everything would test fine but the truck ran like crap even with new Dorman parts. I switched to OBS OEM and it fixed it for about 3 years until I had more melted connectors. So then I switched to the SD style. Other guys run Dorman wiring without any trouble though.

For the SD Conversion:
Valve Cover Gasket for Ford 7.3L Powerstroke (99-03)
Under Valve Cover Harness 99-03 - Riffraff Diesel Performance
Valve Cover Gasket Connector Pigtail for Ford 99-03 7.3L Powerstroke

 

if you ohm ed it all out then it should be good except for the one that's a lli low.


Wiring gets confusing fast. The SD valve cover gaskets have better connectors and only one per side. They don't fail as often but you have to splice them in.


the two front pass one don't change idle when unplugging, since wiring is ok it could be IDM at fault