[Dubaigrand]

Hi Folks,
I recently had a PCM flash to get rid of the infamous jerkiness caused by the 3rd gear partial lockup around 40mph and at the same time the dealership told me they cleaned the throttle body. Well, the engine runs great now and although I need to install an oil catch can to help me clean up the intake, I'm pretty happy with the way the old girl is running with 67,000 miles on the clock.

So the issue is that ONLY when I use the cruise control, I can feel a jerkiness to the vehicle and can feel the gas pedal moving about. I know it moves when in cruise, but this is something more. If I drive manually, the speed is precise and smooth. No uneven speed, surging, etc.

Initially I thought it might be the a/c compressor kicking in and out, so I turned off the a/c and it still does it.

Does anyone else have experience of this issue please, and what did you do to identify and resolve it!?

Thanks, Stuart

 

[Dubaigrand]

Any ideas folks? All help appreciated......

 

[4.whoa]

Well,I havent even seen a 4.7 but that being said, check that the throttle moves easily and the cables arent sticking. I had an old xj that had a poorly routed cable that made it jerky.
Some vehicles are vacuum controlled, if so check for leaks.

 

[Dubaigrand]

thanks. I will try that. I don't get any high rpm issues that are usually associated with vacuum leaks

I'm also getting this weird intermittent ESP thing - it kicks in when I go over speed bumps from time to time (at like 2mph!!) so I'm not sure if a sensor or software fault could be the root cause.
Any other ideas people? Thanks

 

[4.whoa]

I don't get any high rpm issues that are usually associated with vacuum leaks

I meant in the cruise control.some use a vacuum (diaphragm) to move the throttle.