[rustyjack]

Im having the exact same issue with my truck. You just wait, its gonna get worse. before to long your truck will not run more than it does. I sure hope somebody can help us.
When you get time, please try something for me... Start your truck and let it idle for a minute. Then as fast as you can, mash the go pedal down to the floor. If Im right, your rpms will start to go up then drop back down to idle while the pedal is still on the floor. then get off the pedal and step on it slowly and the rpms will rise accordingly. but mash it... just idle. let me know if your truck does the same.

 

[6LiterTeter]

Still suspect the pcm. Are you running an Edge tuner by chance? @rustyjack what you’re describing could be a tps. If there is a discrepancy with throttle position and what the pcm actually sees, all sorts of problems occur.

 

[rustyjack]

Hi everyone. Long time reader here. I've been browsing this forum for over a decade. I am very thankful to have had access to the vast wealth of knowledege this forum provides. Its absolutely impressive. Typically I dont have to post anything. Whatever issue I come across on any of my trucks usually has pages of threads concerning the same issue and how to deal with it. This time it seems I'm not so lucky. There is posts describing the same issue I'm having now but they're old, dead and unresolved. So now I don't know what to do. I'm at the end of my rope with this truck. I don't have much hair left. I have a 2002 F350 Extended Cab Dually 4x4 with the infamously indestructable 7.3L Powerstroke . it's got 131k on the clock .Truck has aftermarket exhaust and cold air intake from the previous owner. I had a PHP hydra chip on it but have since removed it to rule it out as part of my issue. My issue is that the engine randomly just shuts off from time to time. It happens when I parked at idle and/or when I'm running 80mph down the highway. Sometimes it'll come right back to life and take back off. Other times it'll crank and crank but not fire off. It's as if the key gets turned off and back on again. Possibly the ignition switch itself shorting out???When it dies, I can hear the relays clicking under the dash and the glow pug light(WTS),water in fuel light and the engine light come on. And check gauges. just like it does when you first turn on the key. Also .when it dies, it seems I can revive it by pumping the go peddle. It seems like after the APPS resets its ok until what ever causes it to die happens again. Something else I noticed is, if I mash the go pedal to the floor it doesn't do anything and the engine light comes on until I get off the pedal. If I push on the pedal normally the engine responds as it should. But if I mash straight to the floor, the engine light comes on until I let off it and the rpm's never change.
Here's what I've already wasted time and money on and didn't help at all:
-CPS (3x's, last 2 were Motorcraft from local dealership) and pigtail.
-ICP (2x's, both Motorcraft from dealership) and pigtail
-IPR solenoid.( i bought the whole valve but only changed the solenoid so far. I don't think the valve is my issue) and pigtail.
-2 new batteries
- removed PhP Hydra chip
-new IDM
-Cleaned and inspected the battery + connection going through the firewall to fuse panel under the steering wheel on the driver's side fenderwell.

• taken the dash apart and the driverside inner fenderwell out to unplug an replug every connection and do wiggle wire test.
• unplugged aftermarket brake controller (didn't work anyway)
• oil level is good 1500+ miles until due for oil change

Here's a list of codes I pulled with ForScan U1058, U1059,U1027, U1262, B2658, B1352, B1318, P0123, P0603, and P0284.
When I do the KOEO injector buzz test, sometimes I get no buzzes at all and the P0123 comes up. Other times, it will buzz just fine on all 8 and say test completed successfully. no errors. So what do I do with that?
I took a couple videos of the truck acting up but can't figure out how to post them.
I hope somebody can steer me in the right direction. Otherwise the only thing I can think of to do next is to change the ignition switch and the accelerator pedal assembly. If that doesn't work,.. somebody needs to come get this thing before it catches on fire!
TIA

 

[rustyjack]

Thanks 6Liter Teter. They're holding 1 at the counter for me. Guess I'll go get it before they close. They sure are proud of it. I hope it does the trick. And thats a No on the Edge Tuner. or was that from a different post to somebody else?

 

[Heavy_GD]

I tried to bring it all together for you, it could have been to someone else.

 

[bismic]

First thing you MUST do is address the low battery voltage code.

The second is to inspect the TPS wiring VERY carefully, from the pedal to the PCM. Test the TPS if the wiring looks OK.

The third is pull the valve cover and inspect #8 cylinder/injector - valve train, lifter, injector wiring, etc. It is possible (low probability IMO) to even be wiring to/from the IDM. Could be a bad injector.

 

[Hydro]

Post your vids to youtube, then post the link here
As far as the flaky injector test, may be the power relay -- that buzz test should repeat the same each time -- dont just go by a "successful" test - part of the test is you listening to each injector as it clicks
Clear those old codes and see if any fresh codes popup
Cutting off and resetting the dash unit like that indicates a loss of electrical power -- take a look at the back side of the fuse box under the hood -- looking for corroded terminals / wires

 

[rustyjack]

Hey Hydro, Im still trying to post those vids. I got them up on Utube, but I have no idea where the link is or was.
I keep clearing the codes every time I think I fixed it. They all come back.
I dont understand why I dont hear the buzzes during the buzz test sometimes. other times, they all sound off just fine.
Doesn't look like I have a fuse box under the hood. there's several relays with little covers on them. they're not in a box or a panel tho. I have checked the battery connection over the drivers fenderwell. Have any other input or ideas? I appreciate the help. Im totally stumped!

 

[bismic]

Even though they are new, charge you batteries and then have them load tested ............

Then have the alternator tested.

There is more, but do that first (post 6)

 

[rustyjack]

First thing you MUST do is address the low battery voltage code.

The second is to inspect the TPS wiring VERY carefully, from the pedal to the PCM. Test the TPS if the wiring looks OK.

The third is pull the valve cover and inspect #8 cylinder/injector - valve train, lifter, injector wiring, etc. It is possible (low probability IMO) to even be wiring to/from the IDM. Could be a bad injector.

Bismic, P0284 is one of codes that hasn't come back and the low voltage code is what prompted me to get new batteries..But just to rule them out for sure, I will charge them individually and load test them.
And for the TPS, what am I looking for exactly? How can I test it?

 

[Hydro]

You have the PC or lite version of ForScan ?

You can monitor the TPS from ForScan and also the Idle Verification Switch while you operate the throttle -- can do this with the engine off, key on
The IVS should only switch at the idle position, and is the cause of a lot of problems in these trucks
The TPS has multiple resistance track that are monitored, you should be able to see the voltages change in ForScan

A common failure is the harness near the TPS especially if you have the adjustable pedals -- also the floor mat can get pushed up and mess with the harness

 

[rustyjack]

Update; New Ignition switch didn't help. It actually ran (idled) for almost 30 min with out a hiccup. Which made me start thinking maybe I got it. So Started putting everything back together so I could go for a test ride. Got the dash almost buttoned up and started on the inner fenderwell. while I was trying to get the inner fender well in place ( hard push back to get it tucked under the fender) it studdered a bit. DAMM! I was getting excited. And as I gave the liner one last push to get it tucked behind the fender it died. when I tried to restart it the relays were going crazy and it would just crank and crank and almost fire and crank and on and on. I removed the inner fender liner again and tried it again and she fired right up. So now I think the problem is somewhere in one of the wire harnesses right there under the master cylinder. Possibly going to PCM. Im gonna try and recreate the isssue like when I was putting the fender liner back in.

You have the PC or lite version of ForScan ?

You can monitor the TPS from ForScan and also the Idle Verification Switch while you operate the throttle -- can do this with the engine off, key on
The IVS should only switch at the idle position, and is the cause of a lot of problems in these trucks
The TPS has multiple resistance track that are monitored, you should be able to see the voltages change in ForScan

A common failure is the harness near the TPS especially if you have the adjustable pedals -- also the floor mat can get pushed up and mess with the harness

Ill go out and check that now. I have the windows version on my laptop.

 

[Hydro]

Do you have this junction block and is it in good shape ?

 

[rustyjack]

Ill go out and check that now. I have the windows version on my laptop.

OK. Im out in the truck with my laptop. with the key on looks like IVS is working. Idle or Off Idle depending on if I step on the pedal or not. For throttle position I found TP Rate, TP Mode, and TP_F. TP mode and TP F dont ever seem to change. For TP Mode it says PT and for TP_F I get NO. TP Rate however is all over the place. It starts out at 1024.00 with pedal at rest. If I step on slightly it jumps up to 1792.00 then down to 256 then 1280.00, 768, 0.00, 512.00, 256.00, 1536.00, 0.0 and so on. it changes when ever I move the pedal but there doesn't seem to be any ryme or reason or pattern to what it will change to. And if I floor it it goes back to 1024.00 (same as Idle not on pedal at all).
Does this sound normal for the TP Rate?

Do you have this junction block and is it in good shape ?

View attachment 784286

Yes. It's clean and in good shape.

View attachment 784287

Yes. It's clean and in good shape.

 

[Hydro]

Sounds like the throttle potentiometer is bad -- you should get a steady reading that increases as you push the pedal
Did you try with the engine off, then with the engine running -- just to see if there is a difference

Would be nice to have one of each truck model in the garage to check against your readings -- but that is impractical
Maybe when I get independently wealthy ...

 

[bismic]

Those (TPS potentiometers) are pretty good at throwing codes. It is the best instrumented system on our trucks.

 

[rustyjack]

Sounds like the throttle potentiometer is bad -- you should get a steady reading that increases as you push the pedal
Did you try with the engine off, then with the engine running -- just to see if there is a difference

Would be nice to have one of each truck model in the garage to check against your readings -- but that is impractical
Maybe when I get independently wealthy ...

Ah ****. So far I only looked at the TP rate with engine off. I'll start it and check it running in the morning.

Does anybody have any info on the SCP wiring? Where does this SCP wiring begin and end.

 

[NoRalPh]

No, no, no, no.... You're thinking about this all wrong

This isn't a "buss bar", hardware connection, kind of thing. This is a "communication protocol" (serial information flowing between modules) error that says that everybody isn't (or hasn't in the Past) sending/receiving information between them flawlessly. VERY Often these "U" codes are the result of Low Voltage.

So, what you want to do is to be sure you've ERASED ALL CODES, and watch carefully for what returns right away.

I would get a Meter and make-up, from some old Cig Ltr Adapter I would hope you have somewhere, a connection that will allow you to monitor Voltage from the in-cab "Outlet". See what that voltage does before/during/after you crank it as well as as it runs and starts to give you trouble. The location for measuring this is more important than At the Batteries themselves.

Google "Ford SCP Buss" and do some reading...

 

[Hydro]

Been down a few rabbit holes in this thread -- From the original complaint, it looks like a connection issue -- Def monitoring that outlet would be a good place to check

I thought the OP was onto something with the problem showing when he was installing the inner fender liner -- nothing further on that one, but in that area is where I think he should concentrate

Main power from the battery to the cab is where I think the problem lies -- testing at that outlet would be a good start

 

[rustyjack]

OK guys. I dug up an old cigarette lighter adapter, cut the end off and connected my digital multimeter to it. Turned it on to V. Showed 12. Dropped to 11 when I started the truck. After a few seconds it came back up to 12, and about 10 seconds more 13. It stayed at 13 as the truck idled for several minutes. Then the relays clicked and the engine died and on the multimeter 13 went down to 12 after the engine stopped.
Now isnt there a PID in forscan that I can monitor voltage? Im pretty sure I remember watching it and noticed a significant drop in voltage when the engine was trying to die and I would pump the gas pedal to try to keep it going. At the time I thought the glow plugs must have caused the drop because they kept getting turned on.
Well its dark now so thats gonna be it for tonight. I want to thank yall for all your help. I feel like a pain in the ***. I really appreciate yall taking the time to try and help me out. Hopefully we can resolve this soon. Thank You!