When I am driving around at mostly slower speeds (like around 25mph), I have been getting bucked and jerked to death- as if I were repeatedly applying and releasing the throttle. I have done some research and it seemed that everyone was saying to consider resetting the APPS. I did that...and, made sure to clean all battery terminals well at the same time with no improvement. I tried to key cycle 3 times to pull a code from the odometer and all it said was "pdone". I did the key cycle AFTER I did the APPS reset so, I am unsure if there were any there before I did the reset (When I reset- I left it all unplugged for an hour). When driving around, if I hold the throttle at a specific point, you can actually feel the pedal going "dead" and coming back. This truck has had the vp44 and the LP replaced about a year ago at cummins and I am praying that it is not related (1 yr/100kmi warranty is just past). The APPS is only an assumption- for all that I know, it could be anything. I have no idea if it is sensor or ecm related and I never found a chart on here or anywhere else saying..."ok, if the truck is doing this, its the cam sensor", etc. I cannot afford the $90. and hour diagnosis by Cummins so, I would like to try to figure this out without them. Any ideas? Any and all help will be greatly appreciated!!

 

find someone with a smarty or hypertech programmer that can read codes or i think atuozone will check it for free

 

Thanks! That is very good advise! btw, since I obviously should have checked for a code before the reset, does anyone know how long or how many key cycles before they are supposed to show back up (provided I did not temporarily "fix" the problem)?

Also, from what I have written, does this appear to be an APPS problem like I was originally thinking?

 

It does, but the reset procedure should have marked the bad spot, and then the ECM will ignore it, unless you have more bad spots than good spots and the reset procedure won't help any.
I'd hate for you to put a new APPS on it ($350+) and find out it wasn't the problem.


phox

 

Do you have a fuel pressure guage??? If you don't, then you need to get your pressure checked ASAP. Then, at least you'll know it's not VP44/lift pump related.

 

we had a similar problem on our 2001 ctd. it ended up being the TPS ( throttle position sensor), expensive i though. somewhere around the neighborhood of 280 if i remember right. easy change though.

 

Thank you all! Good Info!

Negative on the fuel pressure gauge. Im gonna get to work on that ASAP. I guess I'll just go with a simple underhood mounted deal.

As far as findin out what it is...
Im going to look for codes everytime I drive it- just to see if anything shows up.

Also, after a couple of days of driving, I will take it to my local Advanced Auto and see if they can run the machine on it to pull any codes.

Again,
Thank You!

 

You're perfectly describing the symptoms I had when my APPS took a dirt nap. I eventually got a CEL and P0121 code though.

Symptoms alone aren't enough to justify a $330 purchase though. I agree with finding someone with a code scanner.

 

This is what mine does and it isn't the APPS. The new injectors and the good reman vp44 only made the bucking worse, like shaking the stick at idle and bucks going down a 8% hill. PM me if yours doesn't seem fixable. Hope it is the apps.

 

As an update, I have put about 50 or so miles on it. I guess it is a little better than it was. It seems to still be there though. Its definitely at lower rpm's. With 3.55's and a 5 speed, if I am cruising around some winding secondary roads in say... 4th gear at 30 ish mph, it will jerk and buck you to death -at which point you either have to 1) mash the throttle if not on a grade to pick up speed or, 2) downshift to 3rd- which is just way to low of a gear given the circumstances of strolling along thru neighborhoods. Its not a speed and gear selection that I would consider to be lugging it or too high of a gear for the speed and conditions. Except for being a 24v, its identical to my old 12'er- and it never had that type of problem. As a matter of fact, i used to be able to run MUCH slower in that gear before that happened (thinkin' out loud I guess). I took it to the local Advanced Auto and they hooked up a scanner and it read "Pass" & "No Codes". I truly wish the throttle would just die (at home of course) so I could easily justify the new APPS cost.
Thanks Again All!

 

just a quick question and something you could verify quite easily.... does the truck "act up" if you use the cruise control??

 

Unfortuanately, I cannot say. My cruise control has never worked. I was going to try and figure out why but I'm so used to not using it that I never pursued it.

 

Mine has started doing this same thing here lately. Cruise control won't work at those slow a speeds in these years, so no it doesn't do it with the the cruise on. This is pretty much a city driving or winding country road problem, where your adjusting speeds all the time.

 

so you're both saying it's more of an issue at low speeds and/or low RPM's?

when mine went, it was much more noticeable at low speed/RPM conditions(city driving around 40 mph) but mine also came with a CEL and P0121.

There is another reset procedure(not the one in the tech facts here) but I don't know the link. Hopefully someone will have it and post.

 

Payed more attention to it today, mine doesn't do it much at all while the engine is still cold. Only at operating temp. If you remember first learning to drive a stick shift when you took off in first gear it bucked and kicked until you got it moving, it's the same thing here. My apologies for jumpin in on your thread, just sounds like were havin the same problems here.