Hello,

I've been reading and learned a lot on this forum, but my problem stays. It's a long post to be sure I give all info.

A little history:
I bought a 2001 7.3 PSD in 2011 with 150k miles on it which sometimes had problems starting, mostly when it was cold (40°F or 5°C). Sometimes it ran rough, other times it ran perfectly. The rough running increased in frequency until this summer, when it ran roughly all the time. (feels like on 7 cylinders) By roughly I mean there's a vibration through the whole truck body.

Since I've bought it, I had the starter replaced with a denso starter because it was turning over very slowly, replaced the IPR, replaced all glow plugs, replaced both batteries and replaced the CPS with a black Delphi.

A month ago I was driving along the hi-way and began to run on 4 cylinders instead of 8. Then I've had the UVCH replaced together with the valve cover gaskets. The UVCH and gaskets are one piece now, so they can't get disconnected anymore.

Now all these things have been replaced and again it sometimes runs perfectly, but runs rough when starting with a cold engine and now it's 28°F (-2°C) and doesn't even start at all. It does blow white smoke from the exhaust, but that's after more than 10 seconds of cranking.

Since it's only when it's cold (all things being relative), I would assume it has nothing to do with wiring, but more with the electronics inside the IDM that's going bad? Can the IDM go bad when the UVCH is not well connected?

Any ideas??


Thanks,
Mark

 

I Know you have done all of the right things, I see that, but I am still going to suggest you start with Ohming out the glow plugs, then check the GPR ( Glow Plug Relay)

 

You can check the big wiring harness(42 pin connector) on the drivers side valve cover for frays in the wires.You can pull the valve covers and watch the injectors spit oil as it is running to see if one or more are getting weak.
Good luck and welcome.

 

D+ is Driver-side power to injectors. Just touch the contacts, don't insert the probe into contacts.

 

Thanks for your help. I've already done these things before and tested the relay again today.

Thanks. The mechanic told me he checked the big connector and I also don't think this is the problem, because it never happens when the truck has been indoors or when the engine is warm. If there is a short, it's there every time and not only when it's cold, IMO.

To be honest: I've never removed the valve covers myself and I'm afraid to do so because I only have very little mechanical background and it looks like I have to remove too many things that I'm afraid not to be able to reinstall it again afterwards.

 

Valve covers are a breeze.. and you have a whole mess of people here who have your back.. If you have the patience, the knowledge on this site could walk you through just about any task.

How many miles are on her? I have to aks, because it is starting to sound, to me, you are having injecotr issues.. But I am still learning as I type..

 

You've done all the right things so far.

Put a voltmeter on it the next time you start it cold, and be sure that you see a good voltage drop during the 'wait' cycle, which will show that your glow plugs and relay are all working. I added a voltmeter permanently to the dash, and it lets me monitor this, as well as alternator output. I trust you have a clean fuel filter in there?

 

150k miles. I'm particularly worried to remove the VC's myself because I live 8000 miles or so from all of you, so I can't go to a neighbor who has the same truck. You can only help me online, which worries me too much to do this.

If there's an injector issue, wouldn't that be all the time instead of only when the engine is cold?

Anyway, I think I found something else: I think that the glow plug relay and air intake heater relay were wired the wrong way, so the air intake heater works while it should be the glow plugs and vice versa. I just went outside in a hurry to check that and it looks that way. I would have to test again tomorrow to be sure, because it's already dark around here. (6 PM here) And the engine is warm at this time, so I can't try a cold start now.

Do you know where the other side of these wires end up? I'm asking because it doesn't look like the wires got mixed up on that side, so I assume they were switched on the other side.

(the truck did get sabotaged in a few ways by a previous owner, probably because he saw the repo guys coming - another story)

 

After the injectors get warm they may be spitting better.Look at post #7.It shows the top of the motor.
https://www.ford-trucks.com/forums/1...gine-soon.html

https://www.ford-trucks.com/forums/7...pr-system.html