If cruising at constant speed my RPM will suddenly shoot up 50 RPM or so, engine tone changes - probably just due to RPM change. If I hit a hill and start going up the RPMs will actually go down, once I crest the hill and truck not needing much power to maintain speed it will pop up 50 RPM suddenly again. This is 50 RPM jumps around 70 MPH, and it just instantly, immediate change in tone.

I am thinking the torque converter is unlocking? It actually locks in again under more resistance - going up a hill.

If I am having a torque converter issues, what would I do about it? Or other theories?

 

First thing to do is to see if any codes are stored. If so, address those before doing anything else.

Once you know there are no codes then it will take data logging to see what is happening. Is it the converter unlocking? Is it doing it on it's own, or is the PCM telling it to unlock? You need the answers to these to be able do diagnose what's wrong.

 

I do have an SCT tune and wonder if it's had an impact. Its a canned tune with options, waiting on a custom tune.

Having said that, I didn't notice it when I first had the SCT and it seems to be getting worse (pops up 50 RPM more often).

 

This was due to a bad MAP and/or ICP sensor - replaced both and issue went away.

 

Thank you for following up with the solution to your problem sir!
So many people never let us know how they fixed a problem..... Even after saying they will get back with us and let us know (i understand sometimes a solution is never found)... Your answer WILL help someone someday.

Glad you got it taken care of. :-)

James