Engine/Transmission (1998.5 - 2002) Anyone know how to fix this?

[Fishin Guide]

This is copied from a post made on the NW BOMBers site. A link to current thread is available below.



Okay,



I have been beating my head against the wall on this one, so I am looking for some help again.



In the last several weeks, my truck has a hesitation/ bucking thing going on. Hesitation is not the right word either, it's like someone flicking the light switch on and off about twice a second. There is no obvious loss of power or change of engine tone when this is going on. You just feel it. It acts fuel related, but I have good pressure 14psi and changed the filter two weeks ago. Problem predated the filter change.



I have checked, cleaned and use dialectric grease on every connection I can think of. I just installed my DD UFM last night and there is no change from the EZ. I guess that's good and bad. Air filter is 1 month old (BHAF).



Injectors swapped a while back, checked for leaking lines, no sign of problems.



I seem to be getting erratic engaement of lockup in the transmission, but it does lock up. That's when I really feel this. Also, I have talked to Bill at DTT and he'll step me through the TPS stuff. I called Bill to rule out any transmission issues, however slight, to focus on other areas.



No codes have been set through the key on-off method, but that doesn't mean much right now. Also, no check engine light.



I am leaning towards a faulty TPS. But I am trying to diagnose this without throwing parts at it.



I guess I should mention the turbo. It's there and seems to be fine. PDR35 no real slop in the shaft to speak of, spins easy and makes good pressure on top. 35+ PSI. John will be happy to know that my boost hose clamps have been torqued by a NASA engineering extreme gravity model torque wrench. It's all good!



Thanks for any and all the ideas!!



Dave



Diagnose this problem!

 

[Fishin Guide]

Anyone? I would to figure this out. It would be like giving myself a Christmas present!



Dave

 

[DennyDay]

Bucking?

Did you try it without the EZ?



May quite well be the injector pump.



Good luck,

Denny

 

[isb360]

Dave,



I can't offer you a solution, but sympathy. My truck does something similar on occasion, sometimes worse than others. I haven't gone through all the diagnostics you've gone through, but am leaning toward APPS/TPS as a gut feel, especially since it seems to happen on mine in the throttle "sweet spot" where it spends a majority of the time.

I've seen the photos online of the autopsy of the APPS and it makes sense to me that the wiper contacts would wear out a section of the track and cause erratic signals to be sent to the ECM.

No codes or other obvious faults with mine either. Though, when I have the PM3 box turned on, it seems to "magnify" the problem slightly, something that also makes sense to me.



Take care.

Tim

 

[Dukenrock]

Torque converter? Do you have any afetrmarket kit on the engine? (banks, etc)

 

[mhenon]

Faulty crank position sensor??

Mike

 

[Fishin Guide]

Just a couple of answers to the questions posed.



I do in fact have an aftermarket transmission. I have been in contact witht the builder, but we are reasonably sure the issue lies somewhere else. time will tell.



I do have mods on the truck. Including a DD-UFM, no wire tap, EDMs, PDR35, BHAF, ect.



Dave

 

[mgoncalves]

Probably not what you want to do, but I would replace the APPS. I recently changed mine, and it fixed issues I didn't even realize I was having. I'm sure you can find them cheaper than I did though, $480 with tax at the dealer, yeah... . dealer... . that's it.



Matt

 

[RRFinch]

I have had this before. It could be either the TPS or the VP44. Both will cause this condition. TPS is easier and cheaper to fix and seems to be a common problem. I recommend you start there.

 

[Fishin Guide]

Is there a way to test the APPS, or do I need to have my local shop do it with the scanner? Not that I don't want to do that or anything, I am just trying to keep my wallet in my pocket until after Christmas.



Dave

 

[Fishin Guide]

I got a few more suggestions via PM from TDR members today. I won't have a chance to try them out 'till tomorrow, but I am hopeful.



Thanks guys.



Dave

 

[tgee]

My brothers 2002 had same problem, at highway speeds, but is six speed. Dealer first replaced lift pump, but no cure. They replaced inj. pump, problem solved. Am going to get him a fuel psi gauge for his birthday!

 

[silverram323]

I have this problem also, Just replaced the APPS (TPS) and its still there. I hope its not the VP44 Again. First one at 60,000 and 117,000 now.

 

[MWeagly]

had the same problem with my 99 took into the dealer and they flashed the computer for erratic torque converter locking and unlocking only took about ten mins. truck been running fine for 8 months now it maybe that.

 

[BarryG]

It sounds like a problem I have had a couple times. The first time it started doing it it was very cold out (<0 ) I was on a road trip cruising about 65-70mph. It was a constant one second cycle. Couldnt even really feel it, you could just hear it. No change on tach, would go away if I accellerated or slowed down but as soon as I leveled out to a steady cruise it would be back. Ez on, off, cruise on or off even stopped shut off truck still once back to cruising speed it would do it. Didint seem to do it under 50mph. After about 150 miles of this it stopped doing it. Then about 30 minutes later it started again. After a while it stopped and didnt do it again until a month later then when it was cold it would do it but only under low speed cruise conditions 30-40mph. Then it became more frequent but only under low speed cruise. Then my vp went out didnt hear it again after that until earlier this year and only when the temp was under 50. Same sort of thing occassionally at low speed cruise well I just replaced my vp again and havent heard it since though it sure as heck hasnt been under 50d here since the replacement. Could be a sign of things to come with your vp. Hopefully not.

 

[RacinDuallie]

We had the same problems you describe- tried all the usual tricks and tips the only thing that solved it: Took it to the dealer for the PCM to get reflashed- guess what : IT WORKED.

 

[Herman8r]

Dave--I had the same type of problems---vp44--again! There have been new upgrades to the bosch pumps. I am told all of the new or rebuilt pumps have the new upgrades---but make sure to ask--that is if that is the problem.



By the way--I did not have any codes come up.



Good luck, Herman

 

[silverram323]

We had the same problems you describe- tried all the usual tricks and tips the only thing that solved it: Took it to the dealer for the PCM to get reflashed- guess what : IT WORKED.

What was the TSB # for the reflash?

 

[2-ND TIME]

bad PDC

This problem you describe is exactly like mine so here goes. I am going to take the PDC apart and look to see what might be arcing in it!!!! I have some of the scope readings on my readers rigs. Have more but can't get them on. The Alt and batteries are fine and all the other money that I wasted for parts that are good. :-{} :-{} PM me if you like and can go further!! Sorry that you are fighing with this for mine has been since new mine is bad at 1100 to 1275 rpm and has bucked as high as 2200 rpm up a 10 % hill. Can show you what the voltage looks like coming out of the PDC this is why I know why it is voltage related... ... :--) Cummins and cryslurrrr mecs know little about voltage let along more complicated stuff. :-{} :-{}

 

[AHire]

My truck had a slight,split second, stumble at 2000 to 2500 rpms. It was like there was air bubbles going through the injector pump. I could make it do it on flat ground WOT. It has done this for about 30000 miles. Talked to a couple of diesel mech. checked every thing we could think of. Two weeks ago, just left the house truck was almost heated up to operating temp and i got on it pretty hard it kinda hesitated then blew more smoke than a pretty hot 12 valve. Two days later got the 0216 vp44 code and dead pedal.