Engine/Transmission (1998.5 - 2002) Engine shudder while towing at realtively low rpm

[LPMorgan]

I am towing a 10,000lb trailer with my 1999 3500. A new problem has been occurring occasionally.

The engine will shudder in the 1600-1800 rpm range on relatively level ground with overdrive engaged and trbo boost below 10. More power alleviates or prevents the problem.



There is no shudder while towing up steep grades in lower gears.



The sudden shudder would be what I would expect from a starved engine, but my fuel pressure gauge shows no change.



Backgound: I recently had a failing fuel pump. The FASS pump I replaced it with DID fail and took out the VP44. The replacement FASS pump would not work at all (FASS denies it was possible and refuses any communication even after I returned both pumps, no refunds) and I now have an Air Dog fuel pump. For years I have had a BANKS system and exhaust brake. My automatic transmission has been rebuilt with heavy duty components.



I suspect some bad fuel, but would appreciate insights from those more knowledgeable or those who have addressed a similar problem.



If I can find a good diesel guy in south Alabama near Gulf Shores I will try to have it tracked down.



Thanks in advance!

 

[Sticks]

Might be your dampener, an injector getting weak, transmission, rear end...

This is a new VP and Air Dog you are running now, or do they have some age on them?

I presume you are not getting any codes?

This Banks stuff - performance chip? If so pull it and see if the problem persists.

Any smoke out the tail pipe while the shuddering is occurring?

EGT's during the same?

 

[LPMorgan]

No codes. Air Dog and VP have been in less than 6 months. Will watch EGT and try yo watch for smoke.
Thanks, will report back

 

[JLandry]

LP,



Can you please describe the shudder in more detail?



Questions:



What happens to the engine rpm during an episode?



Does it change in character if you apply more (or less) throttle, but don't change gears?



How long does an event last, and does it eventually stop on its own?



Thanks,



John L.

 

[RonaldLarson]

Sounds a bit like my earlier issue with an Edge box. Unplugged it, and the apparent defueling went away. Got new Edge, (Warranty) but I have not installed it yet. All gauges read normal, old VanAAken box did not act up ever, same conditions with an even heavier load. I agree, unplug the Banks crap.

 

[Road Dog]

Mine does that and I blame slipping T/C lockup clutches. The first step is to adjust the throttle cable that goes to the transmission. It controls the line pressure used to lock the clutches. Less throttle = less line pressure = softer smoother shifts. It's all about comfort. Next would be getting the pressures checked and maybe a new governor solenoid and sensor.

 

[LPMorgan]

I will try to answer the questions and thank all for their help so far.
I am heading south for the winter and do not travel every day. We rest, sight-see, work on the web site, and so on.
I traveled today, and there were NO EVENTS at all. To answer the question about how long an event lasts, it only lasts a few seconds before I turn off overdrive (and thus shift down to 3rd) and the shudder is gone.

I think I have been dealing with two things:
1. some bad fuel. If the problem does not come back, I will believe this is the case.
2. some sloppy driving -- I may have been letting the truck slow down too much while towing a heavy trailer in overdrive.
Today I heard the engine begin to vibrate "lugging" which has been normal for this truck in the past when I get sloppy.
I think the bad fuel, coupled with the low (too low) rpm gave the shudder.

I will continue to monitor.
If anyone knows a good diesel guy in Alabama (between Mobile and Gulf Shores) I will have the truck checked out by someone who knows more than I do when I get there.

I look forward to meeting some of you down the road.