So I've had this problem for a few weeks. When driving down the road if I hit a bump the rpms will jump. The amount of jump seems to depend on the severity of the bump. As little as 100 as much as 500.
If I let off the throttle when I see the bump it doesnt do it. And it also doesn't do it all the time. It does it with or without tow haul on.
So far I have replaced the tps, all transmission solenoids, iac, checked the band adjustment in the trans. I also watched the scanner graph and it doesn't seem like there is a signal coming from the brake switch telling the pcm to unlock it.
It doesn't feel like a slip. My initial thought was the torque converter was briefly unlocking.
I'm kinda scratching my head right now. I don't want to cause damage by driving it but I need it for work. And even my local shop didn't have any ideas past what has already been done. The transmission and torque converter have about 25k on them. Any ideas would be appreciated.

 

Could it possibly be caused by a misfire of a cylinder? Might want to check your spark plug wires, along with any other potentially defective engine wiring that may cause a potential misfire when hitting those bumps. Also, monitoring live data via a scanner while driving may provide some potential clues as well.

 

Indeed it sounds like it could be the TC unlocking. Can your scan tool read the transmission functions ? Would be interesting to see if the PCM actively unlocks the TC. Around here I have a road with a little rise where the TC unlocks for a split second almost every time. No idea why but the PCM does it.
If it's something actively done by the PCM it's probably not a transmission issue. Look into a possible engine issue along the lines of AtomicDog's suggestion. Live misfire counters, TPS and MAF reading etc.

 

try moving components (vac lines,wires etc) and see if that makes it do it then you should be able to find it. Possible bad pcv valve? Maybe the bump is allowing the valve to open.

 

So it doesn’t do it when you take your foot off, is the bump causing your foot to do a quick blip of pedal and your not noticing it?

 

So I drove it about 7 hours round trip yesterday. Had the scanner plugged in and monitoring it. The throttle percentage from the tps doesn't change. So I don't thing it's a quick blip of the throttle. Had that idea too. Had 0 misfires on the counter. I will check the pcv valve and vacuum lines when I get home. My scanner can monitor trans signals I drove and recorded them there wasn't any noticeable spikes on the graph.

Maybe I should note as well while driving at certain speeds I have a constant 50 rpm fluctuations. That started after I installed a 52mm throttle body about 2 years ago. Forgot about it. But I thought it was a side effect.

 

Hmmm...well is the throttle plate tight? Kinda grasping at straws but it's an odd problem

Definitely post up the final solution when you find it!

 

Did you perform any mods/adjustments to the IAC when you installed the 52MM throttle body?

 

I didn't perform any mods with the new throttle body. I didn't think they were adjustable. I hoped the pcm would make its adjustments. I'll check the tightness of the throttle body when I'm home tonight. Is it possible that the torque converter is unlocking itself? Being mechanical proble. That wouldn't be visible on the scanner correct?

 

It doesn't take much for the tcc to disengage/engage.... It's possible that the the scanner simply doesn't react fast enough to catch it. Does tcc bounce when you are cruising steady-state, with small adjustments of throttle?