Truck loses power after acceleration and SES light comes on

[Pigman]

I bought a 2001 F350 exactly two weeks ago and it has run great up until Wednesday. I installed a Hydra chip from GH on Wednesday and when I test drove it, I got about 1/2 mile from my house and it was almost like the engine had died during acceleration. The SES light came on and the engine was running but it was idling very roughly. I pulled into a driveway, shut it off, waited about 5 minutes and it fired up normally and I got it back to my house. I rearranged the cable for the chip, thinking maybe it was pinched, and I drove it for the next hour with no issues whatsoever. Then I drove 20 minutes to work yesterday morning with no issues, driving in the Economy and Street tunes and pushing it fairly hard. Then when I left work yesterday it started up and idled fine, but when I got out on the main road and started to accelerate it stalled out again and I wound up having to get it towed back to the house.

After reading through forums for hours last night, I went to the dealership this morning and bought a grey CPS thinking maybe that was the issue. After the new CPS, the truck started and idled fine for 10-15 minutes. Then I drove it 3 miles before it stalled out on me again during a hard acceleration. I had a friend come pick me up and when they got there I cranked it up one more time just for the hell of it and it ran long enough for me to get it home, although it did stall out about 100 yards away from the house so I had to coast the rest of the way.

Also, just to be clear, the engine doesn't completely stall out and die. It still runs and I can rev it up a little bit, but there is a SIGNIFICANT loss of power.

I'm hoping to get it towed to the shop sometime next week to get codes pulled and get to the bottom of it, unless I can figure out the issue before then.

Any ideas?

 

[Arisley]

Pull the chip out and see if the problem persists or goes away.

If it goes away, check to make sure you cleaned all of the silicone off the contacts for the chip in the PCM. Make sure you didn't take off the tinning on the contacts.

 

[powerstrokinfirefighter]

If the truck ran fine before the chip install, I'd imagine that's where your problem is. Have you tried pulling it out, and running the truck stock?

Beat me to it ^

 

[Pigman]

Sorry about that, I did pull the chip after I got the truck home yesterday. It started fine this morning without the chip and before the new CPS, idled for 5 minutes before throwing the SES light and beginning to idle roughly. The test drive described in the OP after the new CPS was also without the chip.

 

[ToMang07]

Sounds kinda like UVCH. Have a way to get the codes?

 

[mandkole]

^^^ this. Need a good scanner (not Autozone type), or auto engenuity, etc.

 

[Pigman]

I'm hoping to have a friend come out tomorrow or Sunday to scan it. Worst case, I'll have to get it towed to my friend's shop next week to get it scanned there. The previous owner mentioned that the fuel filter needed to be changed soon so I'm about to do that and see what happens. From what I've read online, it sounds like a clogged filter could cause the same issues I'm experiencing so we'll see...

 

[6.0 Tech]

Also could be plugged fuel filters in the sending unit. They like to screw with you when you really need it and are on the throttle. Had a couple of big ass trucks at work do this to me a while ago going up a nice steep hill, almost didnt make it up...

 

[mandkole]

I'm hoping to have a friend come out tomorrow or Sunday to scan it. Worst case, I'll have to get it towed to my friend's shop next week to get it scanned there. The previous owner mentioned that the fuel filter needed to be changed soon so I'm about to do that and see what happens. From what I've read online, it sounds like a clogged filter could cause the same issues I'm experiencing so we'll see...

Sure, you could a few things going on. Read the codes, clear them, see what comes back after a little drive. Typically on a 7.3 a fuel system issue won't show up on codes. Good luck!

 

[Pigman]

UPDATE: Replacing the CPS and fuel filter did not fix the problem, and 4 or 5 codes were found which my mechanic said would not have anything to do with the issues I was experiencing.

Yesterday I pulled both valve covers for the first time, and it wasn't nearly as bad as I was expecting. The passenger side UVCH was tight but the driver side was loose by about 1/4 inch. I went ahead and did the 50 cent mod and so far I have driven a total of 2 hours with no issues whatsoever! Thanks again for the help guys!

 

[mandkole]

Given your description, it wasn't the fix I was expecting but rock on! Well done! :toast:

 

[Pigman]

Well the 50 cent mod held up for a month but the truck started acting up again today. Same exact symptoms so I'm going to pull the valve covers on Friday and see what's up. I'm thinking about just replacing both harnesses but I have a couple questions.

How difficult is it to replace the harnesses? If I can do the 50 cent mod myself can I basically do the harnesses myself?

Do I need to replace the VC gaskets as well? How hard is it to attach the harness to the gasket? And what tools are required to remove/install the harnesses?

Thanks!

 

[Arisley]

Simple to replace. A good pair of needle nose pliers comes in handy, but not required. The harnesses simply plug in to the valve cover gaskets. I put a dab of Permatex No.1, the kind that hardens on the corners of the plugs where the harness plugs into the gasket. It makes the harness and the gasket pretty much one piece. I leave the outside alone, that way I can unplug the engine harness from the gasket and remove the gasket and the UVCH as a single assembly.