I just got back from thanksgiving and over the period of the trip my throttle started to surge with no change of the throttle. It only happens when I am going slightly down hill and the pedal is barely depressed. It also happens when the cruise is set under the same situation. And if I accelerate or chop the throttle then it doesn't happen just when it is barely depressed to keep from getting engine breaking. Any ideas?

 

you got a box on the engine, if so the box is confuseing the ECM.

you might also need to reset the TPS, should be in the manual on how to do this.

edit: oh, and one more thing find a steep hill and floor it, trust me on this one, I found out by accident that sometimes the ECM needs to reset the fueling and boost curves. plus you get to clean out the muffler, you'll see what I'm talking about in your side view mirror

 

i got a similar problem too. While cruising at a constant speed and no change in the throttle pedal, it will surge. Quick surges, sorta like a cylinder wasn't firing as well as the others.
Now I got a power puck that was just installed and it only happens when it's turned on.
Does anyone know off-hand how to straighten out the ECM and recalibrate/reset the TPS?
I'd tried the "hold down the trip reset and turn on the key" trick but i think that only checks the gauges and not the TPS

-Thanks


2004 QC 2500 Cummins