Engine/Transmission (1998.5 - 2002) rpm variation

[blee031]

the rpm variates while cruising under light load around 65mph and while O/D is off while the engine is in a low load situation. It hasn't thrown any codes. Any help would be appreciated.



98. 5,2500,220k,van aken,fass,DTT trans,k&n

 

[Joe Mc]

Could be crank or cam sensor - I've replace the crank sensor 2 times on around 100k on mine. I think Geno's has them now so there easy enough to get. Any codes at all?

 

[blee031]

none other than the usual over boost code i have a crank sensor but never replaced it mostly because of having to remove the starter. Ill change it and see what happens. thanks for the info

 

[madmanmanick]

one possible thing it could be is that the torque converter is going out. to test it out find a flat stretch of road, put the cruise control on and watch your RPM. If the rpm fluctuates while at a steady speed that will indicate the problem. hope this helps.

 

[barryg41]

One bad battery could also be the problem. I have twice had the same problem from one of the batteries being bad. Changed both of them and the problem went away for me. DTT noise eliminator helped and covering the ground behind the alternator with tin foil, then using black tape to cover the tin foil. Electrical noise is a major problem with 99 truck.

HTHs

 

[Vaughn MacKenzie]

Might also make sure your MAP and IAT sensors have good clean electrical connections, and that your IAT isn't dirty.

 

[blee031]

i have changed the batteries last month and the map and intake temp sensor during the summer.