Dead pedal when cold
 

My 2001 Dodge Ram 3500, 5.9L Cummins (stock) has recently been going "dead pedal" when cold (like below freezing overnight). Starts easily, idles nicely, but when first starting out the rpms won't go over about 1800 no matter how hard I push the accelerator. If I pull over, stop the engine and restart, everything is fine for a couple minutes driving, and then the pedal goes dead again. Limp mode? NO check engine lite or codes are showing up.

If i shift to neutral while running I can rev normally, but in drive the dead pedal returns until I stop/start the engine again. After warming up for 5-10 minutes the truck runs great again - until I stop for a couple hours and the engine gets cold again. Then same problem returns.

I don't think it would be lift or injection pumps (I hope) since I wouldn't expect them to be temp dependent or work ok after engine stop/start. Sounds electrical to me since stop/start seems to temporarily fix it. I have guessed that APPS or ECM or some sensor feeding the ECM may be to blame.

So far I've unplugged/replugged APPS, cleaned APPS ground, and recalibrated the ECM/APPS by slowly pressing accel down and up with key on. I didn't disconnect batt first though as some recommend - is this really necessary? (Service Manual doesn't mention this.)

Hard to troubleshoot this because many mornings here (New Hampshire) aren't cold enuf (yet) to even cause the problem.

If the problem returns (may have to wait a day of two for colder weather) I plan to measure APPS voltage next.

Any ideas on what to suspect/test next?

Thanks,
Jack

does your truck show any codes?????

do you know what your fuel pressure is looking like?

1. TPS(throttle positioning sensor), it's right above you injection pump. These are notorious for going out and causing Dead Pedal. Not an expensive fix but I'd recommend having your mechanic doing it.

2. It could be your injection pump that has cracked the diaphragm. I really hope it isn't but it's a very real possibility. Check for codes, either scanner or the key trick. Something has to come up.

Thanks guys. As I sad in first paragraph, NO CODES are showing at all. I believe the TPS on this engine is called the APPS which I already discussed.

I don't know my fuel pressure. I wasn't smart enuf to install a pressure gauge earlier. By the way, I changed the fuel filter about 2K miles ago, so it shouldn't be that.

If the ip diaphragm is cracked why would the truck work perfectly after I stop the engine and immediately restart, or when the engine isn't below freezing?

I don't have a scanner, but had it scanned at a local garage. Please tell me the "key trick" for reading the codes. Will that disclose all codes from both the ECM and PCM?

Biggest questions in my mind are still "Why only with cold engine?" and "Why no codes?" and "Why does the problem reset with stop/restart?".

Thanks.

the key trick is you turn on off on off on off on in like 5seconds leaving the key on the last time and where it shows your odometer it will come up and show you codes write them down and post them or you can look in your book or google them thats how mine showed the transmission governer pressure silenoid was bad along with a pressure sensor mine would the truck would take of and when it was about to shift outta 1st gear i would get the dead pedal only when th truck was cold if i pulled over and turned the truck off and turned it back on it would go. post up what you figure out sorry so long

Thanks much, Diesel Life. The problem you had sounds very similar to mine, especially the cold weather behavior. Interestingly, about a month ago I had a tranny problem that was FIXED by replacing the governor pressure solenoid and governor pressure sensor (same as you had done to fix your dead pedal??). It was AFTER that when my cold temp dead pedal appeared.

It was also AFTER this problem started that I had my codes read at a local service station - NO CODES appeared. I just ran your "key trick" procedure and GOT code P0216 (Fuel Injection Pump Timing Failure). However, my MIL light is NOT on. This would indicate, I think, that the ip problem was temporary (I hope!!). Since 0216 can be caused by high pressure supply restriction or low fuel pressure (according to my service manual), I'll have my local diesel injector service place test my pressure - hopefully on Monday.

Anyway, I suspect that the new ip code has nothing to do with my dead pedal since there were NO codes (for a while) AFTER my dead pedal started.

After running the key trick this morning I drove the truck around the block (33 degrees overnite) - NO problem. Guess it has to be colder to see it.

Thoughts??
Jack

Yep, STILL have the problem!
:argh:

0216 is the death of vp44 code

Altho I still have my 0216 code, my MIL (check engine lite) is NOT lit and it doesn't seem to blink on intermittently while I'm driving either. Also, the truck runs great as long as the engine is above freezing.

I checked the APPS signal voltage when the engine is cold and the dead pedal problem is present, and got 0.352 volts. Other threads have stated that it should be about 0.580 volts.
After the engine warmed up, and the truck was running great again, I remeasured the APPS voltage and got 0.357 volts, essentially the same. I was expecting/hoping that it might jump to 0.58 or so.

This suggests to me that, although the APPS voltage is lower than normal, a faulty APPS may NOT by my problem.

Has anyone ever seen a lift pump or injection pump that caused this dead petal behavior ONLY at low temperatures???

Thanks,
Jack