hey guys, My xjr is having random fits... every once in a while it will go into this mode where it is violently surging under light to moderate loads, its fine if i go to 60%+ throttle...no codes present! it usually just snaps out of it on its own, sometimes after i shut the car off and start it back up... Its like Im jabbing the throttle in half second intervals... but only at normal acceleration...as soon as i put it to the mat it is fine??? and it is totally random...never know when its gonna do it... its def not like an electrical missfire, more like a fuel issue maybe? soo annoying!! lol I also dont believe it is a traction contol issue either... when the traction engages doesnt it usually **** immeadiately... my car is not shifting,, it stays in first...it will also do this at higher speeds when lightly accelerating..just not as noticable because its in a higher gear.... also just for the record it does have an upgraded crank pulley for the supercharger. i have checked everything that i thought of and everything seems to be in order. Just wierd that its so random.. seriously most of the time its ok then out of the blue when i start the car it just goes into having a fit...like its pissed at me lol ...it has never gone for running good to having the fit while driving...it only happens on a start up... then i usually have to shut the car off to get it to snap out of it.. sometimes it wont but then the next day i go out start the car and it runs perfect//
thanks in advance for any advice you may have
Rocket

 

I've moved your post to the X308 section where you'll get expert help (possibly!!)

 

It's EXACTLY the symptoms I had with a loose Throttle Position Sensor connection. I fixed it THIS WAY, but there is the normal fix of replacing the connector pins.

 

Thanks for your input super sport... I will def give this a try. Although it doesn't seem to be related to hitting bumps or anything like that. I will def attempt to clean up the terminal and see if it makes a difference. I'm thinking that's not what it is though so if anybody else has any ideas, throw them my way!
Thanks

 

On mine, it was not only when hitting bumps, but after time, that made it happen more. When it was not connected well, it would just happen any time I was driving.

Like with yours, when you press the throttle more, it cleared up mostly. Although, in time, even throttle did not help as much.

To verify if it's it, you can just unplug and replug the cable and see if it clears up for a day or more. When I'd do that, it would clear up for about a week, then come back.

Also, this happened even after doing the MAF, Throttle Body, and Part Load Breather cleanings. Be sure you've completed those.

 

Might be worth actually watching the operation of the electronic throttle to check it's moving smoothly. Remove the large piece of air trunking between the air filter & throttle body top, then turn on the ignition without starting the engine. Slowly press the accelerator pedal & watch for the smooth operation of the throttle plate as it opens.

You should be able to see it moving if you stand by the door while pressing the accelerator pedal. If it doesn't move smoothly, it may be worth cleaning any carbon & oil deposits from the throttle plate & around the body-taking care to avoid letting anything fall into the throttle