Engine/Transmission (1998.5 - 2002) acceleration roughness

[DEspen]

any ideas on why my 99 2wd is rough on accel at 70 mph+ ? that's with 2k camper in the bed at 6000 ft altitude.

 

[Sticks]

Truck detailed info and mods please. Based on the info provided, I can come up with 70+ reasons.

Also, flat or climbing a hill?

Frequency of symptoms and how long has it been occurring?

Mileage?

Recent repairs or replacement of engine, transmission components.

Maintenance.

 

[DEspen]

more info on rough accel. 60k miles,does it on flat or hill, just started after fixing a driveshaft vibration thing that started after a SB clutch install. found 4 degree difference between front shaft and pinion so put 4 degree wedge under spring. that fixed the driveshaft vibration but came up with rough accell problem. also in working the vibration thing I put a new rear mount in and moved the overload spring bumpers from one side to other since they had about 3/16 of wear from 60k miles of the camper load. has a banks git-kit. pretty good on maintening things. oil and filter at 3k, fuel filter 20k or so. besides burning the OEM clutch launching 12k lb boat only failures have been thermostat and boost sensor which weren't recent events. don't know if it's same thing but for several years there has been a similar but lower level roughness when I load it down with a boat load and trying to pull a hill at too low an rpm. a downshift usually fixed that roughness. I'd like to blame something that happened during the clutch install but haven't found anything yet.

 

[Sticks]

Fuel pump OEM? Gauges? Fuel pressure?

Any smoke on accel both off the line and rolling start?



Check for codes?

Sounds like a fuel system issue.

 

[B.G. Smith]

If you have two piece drive shaft I would check the center support bearing (referred to as carrier bearing by most). bg

 

[DEspen]

oem lift pump and mounting,14 psi at idle, 10 psi minimum at load. had some Sea Foam in the last tank could that be it? no codes.

 

[Sticks]

Never heard of Sea Foam in Diesel. Is it even "made" for that application? I thought it was a gas burner only thing.

I'd wait to hear from other members that have used it before I say good or bad with it.

Possible bad tank of fuel if this is a recent thing. One bad tank will trash a fuel filter in short order. Pulling the fuel filter housing and having a look at the contents may be in order (IIRC the 98. 5 - '00 were the removable canister, not the top loader). Cloudy fuel = water.

If that checks out OK, and the Sea Foam is OK, then I'd do a rev test. Engine at operating temps, vehicle in neutral. From engine idle, fully depress (floor it) the throttle and hold at full revs. The tach should climb smooth and quick, and other than a puff of black smoke at the start, should be clean. White smoke and hesitation in the revs both in climbing and at full would indicate possible VP issues, water in the fuel (hopefully ruled out), low fuel pressure (you are good there), or air in the fuel.

If that is OK, then I would be starting to look at the APPS

 

[DEspen]

to close out the vibration thing. filled the tank diluting the Sea Foam and vibration is much reduced. must have been unevenly cleaning injectors. response seems more crisp with possible power increase. test will come this weekend with 800 mile round trip to lake powell to introduce new SB clutch to boat launching and retrieval of boats including the 12k lb houseboat. thanks for the help I've learned a lot.