ok so first post in a while sorry, but been getting a p0452 code. recently replaced gas cap, fuel pressure sensor, and fuel pump seal. it didn't seem to fix the problem scanned and cleared the code and every time i turn off and restart the truck it comes back. I never get the whoosh when i take the gas cap off. not sure if its related to this or not but, i also suffer the 100 rpm jump at about 80km plus as soon as im steady with the gas any help would be appreciated

 

Could there be a problem with the gas vapor recovery system?

 

Just for the 100 rpm jump.

What is it doing exactly at that speed? In which gear?
Could simply be the TCC (torque converter clutch) engaging which it would do in the situation you describe. Should also be doing it in 3rd gear and 4th (OD). When it engages you will experience an rpm drop of around 100 - 200 rpm.

 

error_401
only at highway speeds 80km up to 110 don't drive much faster and its a 100 rpm jump repeated consistently like 30 seconds apart maybe

 

Does it do this 100 rpm jump even with cruise control on a level highway?

 

yes cruise even tried it this morning its like every 3 seconds just jumps and jumps

 

Mine did this only when 50mph+ (80 km), completely warmed up, and steady cruise in OD with TCC engaged. Not every 3 seconds, but maybe every 30 like you say. Bugged the heck out of me for several weeks. Even set a P0300 and turned on the SES light one time (but usually not). Then I drove 200 miles RT to Chicago and the transmission went out to the point that the vehicle wouldn't move unless you sat for several minutes to let all the clutch material fall off the fluid pickup filter. Otherwise it just sat there and howled because of no fluid to the pump. After trans repairs the problem went away. I think it may have been evidence of the pending trans failure, but I don't know that for fact. Please do follow up and let me know when you find out the source of the problem.

 

it does it continuous when im at highway speeds but seems to go away for a moment when i tap the breaks, it seems to gear down for a second then after a bit shifts and goes back. i find it more of an annoyance then anything and wondering if it have anything to do with my intake(have to do a lower intake gasket)

 

You might want to look at your TPS with live data, first at rest while smoothly moving and holding the accelerator through different positions to rule out a bod sensor. I agree with Les that this may be a transmission issue however.

George

 

it only happens in overdrive and sadly enough if a 6 month rebuild trans and still wondering if it could have any relevance to my toast lower intake gasket (being done tommorrow)