Sorry for the double post, but I am in desperate need of some help! Please read and offer any ideas you might have...


Ok, I just went on a 5000k trip and on the way back my truck (2001 F350 7.3) started doing the weirdest things. First the turbo kept blowing off pressure at much lower RMS than it should (BTW I was towing about 6k and had a camper on it) usually about 2000 RPM or so. it normally doesn't blow off until around 2600-2800 RPM with a load. So it became almost impossible to do more than about 30k up standard hills I should fly up. I pulled over at the side of the road and checked for codes, I had a code saying that the Barometric sensor had a problem, and I had a code that said that my turbo pressure sensor was having probs. I cleared the codes and returned all programming to stock. All was fine for about 10min when it began to progress again from slight problems to the point at witch I couldn't even drive up a hill. Cleared codes again and all as good for a while.
After reading online through this process I found something that said to disconnect the MAP sensor if these codes were coming up, I did so and the truck ran like it was brand new again. (BTW Disconnecting the MAP sensor is the only thing in this whole process that gave me the check engine light in the dash.) I drove for quite some time, satified that the MAP sensor was the problem until the truck began to miss and run like a bag of crap. I was now unable to even go faster than about 30k on straight roads.
I hooked the MAP back up and pulled more codes, now the codes were telling me that I had an "OPEN CYL 7 Circuit" and a few other major weird ones that I can't think of right now. I cleared them and that didn't fix the problem.
After letting the truck sit for about 10min all was good again. Then after driving for the ferry it acted up again. Getting progressivly worse.
I got on the ferry (FINALLY) and let the truck sit. 1.5hours later I leave the ferry and all is fine and no problems now. Now that I am in my own town I figured I would TRY to make it happen again, so I shift @ 2500RPM and work the truck a little to try to heat it up so to speak. And the turbo begins to blow off pressure early again @ about 2000rpm and the lack of power and trubo problems return, but no codes now. I removed camper and trailer and now I can't even make it return by beating on it.
It appears that this problem is somehow HEAT related maybe? My truck requires a major LOAD to make this happen...

 

check your UVCH (under vavle cover harness) that could be what is giving the #7 cylinder code. the drivers side has all the even cylinder #s and the pax side is the odds. starting from front driver side is 2468, and pax starting from front is 1357. if it is not the UVCH then you may have an injector going bad.

I am not sure I understand what you mean by" blowing off" when you refer to the turbo.
Do you have guages, and can you tell what PSI your max boost is?

 

Blowing off, I mean that you can hear the turbo spin up but loose boost & power @ much lower RPM like 2000. I have heard the turbo release pressure under heavy load before but usually on a hill @ much higher RPM like 2600 it will start to release making a quiet SHHHHT SHHHT SHHT noise... It was now making this noise @ 2000 RPM before the TURBO even had a chance to spin up fully. Then left alone for a short period of time, all was great until I beat on it for a while then it would start doing it again... and of course... no power once it started... to check the UVCH do I have to replace all of the gasgets? And do I need to remove anything to get access to remove them?

Thanks for the input......

 

This will explain the wiring harnesses, but not the turbo blowing off.
https://www.ford-trucks.com/forums/2...or-wiring.html


Perhaps you might also have a boost leak.

 

What you are experiencing with the turbo is called surge. it can change what RPM it becomes appearant at just by different altitude/load. You don't hear it know that you have everything unloaded from the truck, and the truck is not working near as hard. Surge can be helped one of two ways.(or both if your up to it)
You can do a search for "surge" and it will provide you with many hrs of reading.

1. install a wicked wheel turbo impeller.($70 not guarenteed to cure , but will help)
2. install a ported compressor housing on your turbo. ATS makes a nice one.($400 to 500 and most likely will cure all compressor surge)

Your valve cover gaskets are all reusable oring style gaskets that only need replacing if you should damage them when removing them.

 

Ok, "SURGE" that you are reffering to if normal should only effect the vehicle a little bit I am sure... The "Surge" I am reffering to completely incapacitated me to the point where I was lucky to go 30kms up hills that transport trucks were passing me on. (The same hills that at the beginning of my trip when I was carrying more load I was able to do 100+) So what could cause this "Surge" to happen and progressivly get worse all of a sudden? To me it appeared to be a HEAT like effect... If I beat on the turbo (the same as I did 10 days prior with more load) it would start failing and in fact threw a turbo pressure sensor code which never returned even though the problem returned?

 

the link u sent reffers to '99 7.3... does this problem still exist in '01?

 

Massive exhaust leak maybe, up pipes or manifolds. No power to be had that way. That is my stab. Maybe a cut donut that gets worse with heat.

 

Gotcha, yeah, youre right, normal surge is just a little annoying, I beliee you have an exhaust leak that is not allowing complete spool of the turbo. but first things first check out those UVC harness' and lets make sure all 8 are firing . then we can get to boost leak issues.

To answer the other question, Yes the procedure is the same for an 01 as a 99. (99 to 01 only saw minor changes, mainly in interior, the motor reamins the same)

 

UVC or harness chaffing. Pretty easy to check and probably your #7 issue.

The boost issue. Do you have a boost gauge? If so, how much are you making.

 

UVC harness and the plug and wire assembly on the driver side near the VC always bear checking when there is a problem, but I don't think they care what load or rpm you are at when they act up causing a funny boost loss sound. How's that for a runon sentence?

 

sounds like a couple things going on

couple thngs I may have missed
did you change the fuel filter
not sure if the blow off sound may be waiste gate opening,did you try disconecting waist gate line

 

The only think I disconnected was the MAP sensor when I saw a post here suggesting it as a test for some codes. The blow off sounds like the waste gate opening, but only after some abuse and @ WAY WAY to low RPM compared to normal. Then it progressivly gets worse until the truck is undrivable. U let it sit for 10min and all is good as long as you don't beat it up.

Fuel filter was a thought I had at the time, so I stopped in the dark at the side of the road and changed it anyways, just to make sure. (Didn't help)

Funny thing is, since I have removed my camper and trailer, I have not been able to make the problem return. Not enough load...

 

No Gauge to be able to check, but pretty obvious loss of turbo spin up, and of course loss of power. When the turbo problem started I was not missing on cyls or getting the #7 cyl open code either. That came later when the prolem progressed. Weird thing is, that once camper and trailer removed, all is good... No more probs... Can't even beat on it hard enough to make the problem return. Only seemed to be able to re-create it with a load.

 

I would have thought that any UVC wiring probs would be there almost all of the time, not just under load???
Is there a turbo pressure sensor I can check or test in some way? Could it be effected by heat somehow and then failing?

BTW everyone I appreciate the brainstorming here and really do appreciate your time and help on this... I just feel that if I take it into the dealer for a checkup that it will come back with a clean bill of health... I am not getting any more codes from it now either...