Ok, so I am getting frustrated with this and need some help.

Symptoms:
• Rough Idle, seems like it is missing. May idle up too (1100rpm). Will idle smooth at times too. Can restart engine during rough idle and it goes away.
• Dead Pedal at varying speeds. Sometimes it does just driving down the road or sometimes going down the freeway. Even did it once in the shop while revving engine up and down trying to diagnose.
• Lack of power when needed….when driving down the freeway and you try and push it, engine loses power / dead pedal. Blue smoke comes out (used to be LOTS of black during the dead pedal, now has changed to a little blue as of recent).

Codes:
PCU- 1693 / companion
ECU- P0121 (APPS) and sometimes P0122 (APPS)

Fuel Pressure is good, 14-15 at idle, 7 WOT, cannot drop it below 7. FP is consistent during dead pedal, be it 7 or 14.

The Truck (all stock, original owner): 152,000mi.
118,000- Bad LP, replaced with stock. (me)
131,000- New ECM, lots of gauge problems / dead pedal. New ECM fixed gauges. (Dodge)
135,000- New VP44, fixed dead pedal (Dodge replaced).
145,000- began noticing slight miss at idle, probably only something I would notice. “pushing it” dead pedal began.
150,000- common dead pedal began occurring, rough idle progressively worse
151,000- new APPS, $500 from dodge P/N 53031567AD. Didn’t really do much of anything.
Reset APPS numerous times, including the new APPS.

Hooked our snap-on / SOLUS scanner up at the office, reads same codes. The TPS test showed a good relationship between the pedal and TPS %. We really don’t know how to work the scanner too well, but can understand the basics. Unfortunately, the scanner was not hooked up for real time data when dead pedal / code showed up in shop playing with engine.

Thoughts:
I felt confident in the APPS, but it didn’t do the trick. Could I have gotten a bad sensor?? Symptoms could also be fueling, but FP is good and VP44 has less than 18K on it, plus why the P0121 code? ECM / Wiring problem may be in diagnosis as well, but 2 ECM’s in 20K? I think that would signify a much greater problem!

I am too the point where I am trying to decide if I am throwing good money after bad. I love my truck and it is paid off but I am getting sick of throwing money for major repairs; plus I don’t really like any of the new trucks and I had planned to hold off until 2010. Sadly, we have several 01-02 dodge cummins trucks at work, all with over 250K problem free miles; why not my personal?????

Thanks for any help!

 

" but could 2 ECM’s in 20K? I think that would signify a much greater problem!"

That's what I was think as I read your post. It sure sounds like the APPS or ECM again but there's an underlying problem there.
You might start by removing and cleaning "all" grounds and having the battery and alternator checked. Once you're sure you have a clean 12 volts (no arching or spikes) and hard grounds cleaned of grease or paint then have the codes cleared and see what pops up.
Really sounds to me there's some voltage spikes getting into sensitive electronics. Good luck running this down.
Mike

 

Truck is scheduled to go back to the same dealer that confirmed the ECM problems this past summer. They seemed to do a good job at tracking down the electrical problem and didnt want to just throw parts at it.

I am thinking the dealer is probably the best bet for electric diagnosis because they should be equipped with the best equipment and troubleshooting support.

If they trace it back to the ECM, I think I am going to seriously consider trading the truck in as there is probably an electrical issue that I will be unable to ever identify and will continue having problems. I really like my truck though and dont like the thought of a new one.

 

This is a tough one.

Dead Pedal is really only one of two things when the truck is otherwise running smoothly: ECM or APPS.

If the truck is NOT otherwise running smoothly, then the VP44 is also a possible cause. (specifically the FPCM computer inside it).

I wish I could help you. My recent APPS problem was easier to diagnose, and the APPS fixed it perfectly-- the truck no longer misbehaves.

Please let us know what resolution you get in this, even if it's regrettably having to trade in the truck.

jh

 

Update:
The shop called me yesterday and said they were unable to reproduce the dead pedal; I went in this morning and was able to get it right away, unfortunately the tech was not with me. When the tech road with me with the computer hooked up, it never did it! Very frustrating! The tech is going to look over the wiring harness and fix the common ground problem near the passenger battery and go from there. The tech also said that he has hard wired the parts, bypassing the harness, to the ECM in the past with favorable results. That is probably step 4.

Tech said he was very confident it was an electrical problem; fuel system was testing good. He did hear the slight miss at idle and pinned it on an injector issue; he is going to put some more cleaner in the fuel.

I can nearly always make the truck go to a dead pedal, except when the mechanic is with me!

 

Another Update:
So Dodge calls me yesterday afternoon and tells me that they soldered the passenger battery ground wire and investigated the wiring harness; no issues found. The tech took it for a test and did get the dead pedal (finally!). The tech found a problem with the new APPS set screw so he replaced the APPS under warranty but didn’t think it was causing the problems. Tech finally determines that the ECM is likely giving a bad signal to the APPS causing the dead pedal. Thankfully, the dealer is working with me and has agreed to warranty my ECM less labor. At this point, they think this is the problem and will keep my truck over the weekend to make sure.

Now back to one of my original questions, 2 ECM’s in 6 months / 20K miles? Is something causing this? Tech and advisor say it was probably just a bad ECM and didn’t think there were any contributing factors. Any thoughts on this?

 

This is from Blue Chip Diesel: "There are basically only two other components in the fuel system in a VP44 fueled truck and they are the ECM (Engine Control Module) and the injectors. Neither of these give any trouble typically. In 15 years of doing ONLY Dodge diesels every day, I have never seen or even heard of a bad ECM and or OEM injector. This experience, the fact that they have never been an issue, combined with the fact that replacing the injection pump after the following diagnosis, always fixes the problems, I am very confident in what I say below."
Two ECM's in 6 months indicates another problem. I would still go over the truck with a fine tooth comb looking for electrical glitches. I read about one guy with a loose wire on the connector to the PCM. Caused all kinds of trouble 'til it was run down. Your's could be something just like that.
Mike

 

Last Update:
New ECM was installed and the truck now has over 700 dead-pedal free miles so this seems to have fixed the problem (knock on wood!). Official diagnosis was “isolate as internal ECM failure. ECM reading volts but not percent of APPS change.” The dealer / tech have been great to work with, just hope I don’t have to see them again!

On another note, my miss at idle is still present and I am leaning towards an injector, but this is another thread.