Been lurking on the sight for a while and finally joined. I have gotten a lot of good info and need a little more past what I have found so far.

99.5 F-250 with 7.3 and 234,000 miles.

It all started when the glow plugs were not working correctly (at all). Replaced the GP relay and now it starts and runs fine on cold mornings. Following GPR replacement, I now have another problem. About 6 months ago I filled up and thought I bought bad diesel. It ran REALLY bad and sounded like it had an injector going out (extremely rough idle). Sometimes it would smooth out and run fine and others it would run poorly (even with other brands of diesel now).

The problem: the truck starts and runs perfect when I first turn it on, but the "service engine soon" light is on. It also has very little power when the light is on. If I do not move the truck and just let it idle, the light will stay on for about 3 minutes. Then immediately after the light goes off, the truck sounds like it just about dies, then kicks back up to normal RPM's but the engine runs rough (I can even see the shifter moving side to side)...buuuuuuut, the truck has all the power it normally has. I take it through town and if I get off the fuel it has a sharp jerk (like hitting the brake hard). If I drive it for a while it will just go away like nothing is wrong.

It does not do this all the time. Right after and during a road trip nothing seems to be wrong (starts and runs fine).

I live 55 miles from the nearest ford house and nobody in this town has a tool to check the codes correctly (all say the "service engine soon" light needs to be on for it to get checked. I replaced the CPS with the new $25 version about 30K miles ago. I live in Alpine, TX for the next 2 weeks and I will need to tow a 10,000 lb. trailer to Pinetop, AZ.

Sorry for such a long description, but I figured it would be better not to leave anything out. Any help is MORE than appreciated. I only have one clue what it MIGHT be but I do not know what UVCH stands for.

 

Welcome to FTE. Definitley try to get your codes read first. UVCH Under Valve Cover Harness. This is a very commmon problem with our trucks. The harness under the valve covers works itself back and out and therefore the individual contacts inside the component plug will make a false contact and work intermittently, and sometimes not at all. You can see in the first Picture where the harness has pulled away. The second and third pic's show the common fix for this problem. You cut an edge of a quater, and insert in the area of the clip. This spreads the clip retainers out enough to keep it from sliding out again.

 

Do you know where the ICP sensor is? Driver's side head, front inside corner.

Pull the electrical plug on it and see if there is oil in there.

 

Thanks for the welcome!! Definitly thank you for posting up the pics...I had no clue what people were talking about when they said it would take my time and 50 cents. I may go ahead and check to make sure everything is still good under the covers because of the year of the truck but for now...

Yes, there is oil in that sensor. The one that I found is where you said it would be and more on top (very easy to get to)...is that the correct one?

 

Welcome aboard! I too was a lurker for a little while. These folks are so helpful I just had to sign on! Before you know it you'll be sharing the knowledge you gain and helping someone else out who might have the same symptoms/problems you will/have experienced. I would definitely look at your ipr sensor (as recommended by clux) first since it is easily accessible. If it is clean I would pull the valve covers (as recommended by countrycar) and look at the wiring harness. One other item you might want to check is the exhaust pressure sensor and tube.

 

Oil in the ICP connector is one indication the sensor is bad. (yes it's very easy to get to).

If you look closely at Country's pics, you'll notice the loose UVCH connector in the first pic, and the quarter inserted in the connector to act as a shim in the last pic. It takes one quarter for each side, so that's where the 50 cents comes from.

Welcome to FTE.

 

That is the correct sensor. Probably time for a new one.
I won't guarantee that will fix your problem, but it's a good place to start.

Now, leave the ICP unplugged, start your engine, and see if your symptoms change any.

 

symptoms definitly changed for the good. The check engine light stays on and does not go off...now it seems to run fine and does not have the rough idle if I leave it for a while. The truck just seems to have a nice idle. Any recommendation on where to get that sensor? And wow...thank you, thank you, thank you.

After I get that sensor I am definitly going to post up to let everybody know how it is running.

I am still going to pull the valve covers because I do have the surge when I am going through town about about 40 mph. I did look around on the site and it may be the plug...and it will give me a chance to torque everything back down to spec just in case anything is loose.

I'll also post what happens and what I find after I take off the valve covers.

 

You can probably order one on-line cheaper than you can buy one from a dealer, depending on how much of a hurry you are in. It's ok to leave the ICP unplugged and drive it, as well.

And don't be alarmed if the new sensor looks different, ford has changed the sensor used.

 

Well, the cheapest one that I have found online was $169. Thought that may be kinda high until I went to Napa here in town - $315. So I will be going with 169 (Pure Diesel Performance) and post back up my results.

If anybody knows of one cheaper let me know...I will probably be ordering one tonight or tomorrow morning.

 

Jeez, the last one I bought was from E-bay and I think I paid about $45 for it.

That's inflation I guess.

 

No need to hury, won't hurt driving w/o the ICP hooked up. You should be able to pick up a new ICP for $50-$60 if your patient...

http://cgi.ebay.com/ebaymotors/icp-s...Q5fAccessories