Engine/Transmission (1998.5 - 2002) High RPM Stumble Under Load

[BradyJ]

My mildly mod'ed '02 (VanAken, 4" exhaust) 5 speed was perking along up a moderate grade yesterday at 6000 feet in the Sierras, dragging my loaded flatbed ~11k. I'm wound out in 3rd gear with the pedal down... 3000 rpm, egt is good (975-ish), when I felt a "chug"... just for a split second. Tach didn't budge (happened to be watching), so I figured no slip 'o the clutch or the tires... Almost felt like a "dead spot" in the fuel curve. I backed out of it and took it easy then tried her again on the next grade... same thing... Just when the tach cleared 3k, "chug" then all's well. Didn't have the stones to try it a third time or see what would happen if I kept my foot in it...



Any thoughts?

 

[terrywerm]

Mine used to do that - and it only seemed to do it under load, pulling a grade. FP was fine each time. Happened three or four times on a trip to Colorado, and I didn't see it happen again until some time later pulling a heavy trailer up a hill, down in third gear. At the time I decided to just keep an eye on it.



A short time later I started getting the dreaded "dead pedal" while cruising at highway speed. Retrieved codes, getting the 0216 code on the pump. Took it to dealer three times, they recorded and cleared the codes each time, but they were never able to repeat the problem. After the third visit, they replaced the VP44. Dead pedal problem is gone now, and so is the stumble when pulling hard at high RPMs. I don't know if the two problems were related or not, but it sure looks like they were.



In short, check your codes and take it from there.

 

[BradyJ]

AHHHHRRG!... Code 0216 it is. Got an appointment at the dealership for Friday morning. They've been top-notch so far... miles are still low, so we'll see how it goes. Interestingly, I haven't been able to recreate the smoke. It's now turned into an engineering problem... different speeds, different gears, different grades, etc. I guess since I know it's broken (or at least BREAKING), I'll play with it a bit... Gettin' warm here in Nevada... I'll just ride the bike to work...

 

[terrywerm]

I forgot to add that at the time that the problem first started I did not have a fuel pressure gauge. I added one very shortly after the hard pull stumble started and found that my lift pump was very weak. I had the lift pump replaced (still under warranty at that time) but the hard pull stumble continued, with the dead pedal at cruise starting to occur a couple of months later. When the dead pedal problem first started, it was a pretty rare event, but within a few months I could get it to do it almost at will after driving for 30 to 60 minutes. Dealer replaced the VP44 with the odometer showing 99820 miles. Nothing like cutting it close on the warranty limits!

 

[BradyJ]

dealer replaced lift pump

Ok... Dealership replaced lift pump under warranty. I asked, "How do we know if the VP44 is damaged?" Answer was, "See if it throws the code again. " The interesting thing was that the Check Engine light never came on... I thought that Ecm 0216 would turn that idiot light on...



Anyway, I'm looking at the RASP system, so as soon as I'm reasonably satisfied that the VP44 is ok, I'll install that. I want to wait to make sure I don't have any other problems, 'cause I'm pretty sure that once the RASP is in, the warranty on the fuel system is over...

 

[BradyJ]

4 days later... Great billowing clouds of white smoke again--It would almost look cool if I didn't know what it was. ECM 0216... Interesting that it seems to be happening only when launching (gingerly!) in 1st. Sputter and smoke, then shift to 2nd and it's gone. I'm thinking it's something to do with the relationship between fuel demand and rpm/load. At any rate... I scheduled "round 2" at the dealership. I wonder how they'll explain ANOTHER bad lift pump... that's 4 days old! Then again, I've always been pleased with their service to date... We'll see...

 

[terrywerm]

Been there done that...

The white smoke and dead pedal is a good sign that the VP44 is on its way out. As mine got worse with time, I would get the dead pedal in any gear, always under low to moderate throttle, and engine temperature did not matter. If it happened with a cold engine, I could fog the whole neighborhood with white smoke. Once it snapped out of it, it was usually fine for a while, but not always. When leaving work one afternoon, with the outside temps in the 50's I drove nearly two miles before it snapped out of it. #@$%!

 

[BradyJ]

New Injection Pump!

Dealer replaced under warranty... so all is well. I have noticed that the truck seems to have slightly less "go" under hard acceleration, but it's not enough to concern me. I wonder if the pump is tuned differently?



Anyway... my next two mods (in order) are fuel pressure gauge (with the nifty fuel filter cap from Geno's) and the RASP system...



I knew I shouldn't have sold my '91 cummins... OR the '94... Ah well... at least I can appreciate the really good heater setup in the '02... that '94 never would get warm enough to defrost the windshield back in Omaha...



Kudos again to Carson Dodge... Eric knows his stuff when it comes to Cummins and that dealership has always treated me well...