Surging throttle from start

[absentmathis]

I've posted about this before and had it in to the dealer multiple times but they can't fix it. When accelerating from a stop or very slow roll there is often an obnoxious throttle surge around 1500-2k rpms. I hold the pedal light and steady which should result in fairly linear acceleration, but a passenger would probably tell you I mashed it for a half second...it's enough to snap everybody's head back to the headrest. Then instantly back to linear feel. The transmission was replaced under warranty last year, they've reset its computer several times to no avail. No codes elsewhere. Engine runs great otherwise. Best I can figure it's a glitch in the throttle. The problem does not occur 100% of the time (which hinders dealer diagnosis) but best I can tell is *more* present after longer highway drives. Any thoughts?

Edit: I forget this forum doesn't have car info, it's an '08 48i.

[Arby1028]

Don't have an answer for you but I'm also in Charlotte - take it over to Eurocars on Mint Street and let them look at it.

[smassey321]

Remove the fuse to your 4x4 to rule out the transfer case. Bad clutches in the transfer case can sometimes do this.

[LeiZ]

Done throttle adaptation reset?


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[absentmathis]

Both of the above two are good suggestions. I think so on the throttle but will have that done. On the transfer case note - I'm especially intrigued because I've wondered about it for another reason...I've got newer tires on the back and rolling diameter is different front to rear. Can't figure why that in particular would chase my problem, but maybe clutches could.

[Arby1028]

Originally Posted by LeiZ

Done throttle adaptation reset?

Do you have instructions on how to do this?

[ChuckG]

Originally Posted by absentmathis

I've got newer tires on the back and rolling diameter is different front to rear. Can't figure why that in particular would chase my problem, but maybe clutches could.

If the problem started after the new tires then that is likely the problem. Different diameters between the front and back could cause problems in the long term wearing out the clutches.

[absentmathis]

Originally Posted by ChuckG

If the problem started after the new tires then that is likely the problem. Different diameters between the front and back could cause problems in the long term wearing out the clutches.

No, the problem existed before I replaced the rear tires. Fronts and rears wearing differently is also pretty darn common. I have a hard time believing that could be the cause.

[JCDillon]

I've noticed this with my 08 4.8 also. Thought it was my imagination at first, but I've noticed it more and more. Another thing, when I switch over to "manual" mode, it's not as bad. What is the Throttle Adaptation Reset LeiZ speaks of?

[fast4d]

same here. 08 4.8

have to initial tip into throttle smoothly and gradually. otherwise very abrupt.

so either I go gingerly or 3/4 throttle from a stop

it's my wife's ride so I rarely drive it but when I do it is very noticable