Flickering Check Engine

So the truck has been running well since I picked it up. Have had an issue with fuel pressure based on the fuel system and a sticking valve. Which is getting replaced this weekend... But yesterday, the truck started throwing some codes. I was stopping by TomS house to borrow a leak detector and he hooked it up to AE. Couldn't get AE to run cylinder contribution test or communicate with PCM (much). On the buzz test... It would consistently buzz 5 injectors and then on retest only 3. Not sure if that is a symptom of the root problem or is related to the communication errors AE was giving.

The truck obviously has a miss (thank you Tom). Runs extremely rough, sky high EGTs, low boost, no power, etc. The check engine light will stay on while this behavior is happening. I left Tom's house and headed home to check injector harnesses and 1/2 way home CE light goes off and truck runs normal. The truck ran perfect rest of the way home - maybe slightly high EGTs and low boost but I wasn't pushing it to find out. I checked the valve cover harnesses and they appeared to be nice and snug. I drive in to work today and 1/4 of the way in and the CE light turns on. Truck loses power and has a miss. 30 seconds later - CE light is off and seems to be running fine. It did that most of the way into work (20 miles).

So what I need is a list of things to check. Here is my thoughts so far:

Chip - is it seated and good contact
External Harness - disconnect, electrical cleaner, reconnect
Main Harness - Make sure connection is tight
Under valve cover harness - well this is my last resort...

Any ides?

Sam

Sam, I think it is the under cover harnesses that are an issue on SD trucks but not sure. You might also put up those codes that were present. When I tried to run contribution or buzz AE would say unknown error has occured. I had not seen that on a truck before.

Codes:

B1352 - Ignition Key-In Circuit Failure
P0381 - Glow PLug/Heater Indicator Circuit
P0475 - Exhaust Pressure Control Valve
P0541 - Intake Air Heater A Circuit Low
P0733 - Gear 3 Incorrect Ratio
P1119 - Manifold Air Temperature Circuit High Input
P1211 - ICP Higher/Lower Than Desired (engine running)
P1212 - ICP Lower Than Desired (engine crank or run)
P1247 - Turbocharger Boost Pressure low
P1248 - Turbocharger Boost Pressure Not Detected
P1316 - IDM Codes Detected
U1262 - SCP (J1850) Communication Bus Fault

Sam

Sam if you need to get that cut out box from Austin let me know.

I am going to trouble shoot tonight before I rip the fuel system out. If I can't get find it, I will let you know. Thank you!

Sam

Easy way to check the under valve cover harness. When its running rough. Unplug one side at a time from up top. If it stays running, plug that side back in and unplug the other. If it stalls. That lets you know what side has come loose.

Tom S said:

Sam, I think it is the under cover harnesses that are an issue on SD trucks but not sure. .

Click to expand...

Definitely. There is a Ford repair clip, or you can use a quarter cut in half, or so Pocket says.

Sounds like UVC harness to me for whatever that's worth.

It sounds like you have a loose electrical connection somewhere

Sam I can drive up to your place if needed as well. You need a break.

Gotti2k7 said:

Easy way to check the under valve cover harness. When its running rough. Unplug one side at a time from up top. If it stays running, plug that side back in and unplug the other. If it stalls. That lets you know what side has come loose.

Click to expand...

So I wiggled and applied pressure to the passenger side and it runs smoother. I unplug it and truck runs but really rough... I tried getting the driver side off and couldn't quite get it off but there was no change when fiddling with it. Am I correct in my assumption that I should start with the passenger UVCH?

Sam

Tom S said:

Sam I can drive up to your place if needed as well. You need a break.

Click to expand...

Tom - you are welcome up anytime. I think it figured itself out (passenger UVCH) like you thought. I should be able to get repair kit tomorrow and have it running in no time. If not - back to the drawing board :doh:

Sam

Would be a good cover to pull first

I would say so, if the outside VC harness connector is bad you may need to replace it, be careful, see my post here on nightmare engine problem.

If you need a valve cover gasket, let me know, I have a good one.

Looks like Tom (and others) nailed it... Loose under valve cover harness on passenger side. No parts needed just pushed it over the clip...

Came out to find this wandering around the house...





Sam

So does it run better on 8 instead of 5, 6 or 7?

Tom S said:

So does it run better on 8 instead of 5, 6 or 7?

Click to expand...

Should find out tomorrow when it'll hold 70psi during a run... But for now, no shaken baby syndrome when shifting

Sam

Nice thread timing, my truck just started missing just like yours this morning, a few of the same codes. I figured UVCH and this strengthens my theory.

One of you SD guys could post up the info on those clips. I do not have that saved.

Those clips are definitely a known issue for superdutys. On my old truck when I had the injectors out I used very small zip ties to keep them together. I wish I would have taken a picture.

Tom, are you going to Bandimere tomorrow? I can bring your box of diagnostic goodies with me if you'd like.