Throttle Potentiometer
 

So brief bit of a story before the problem. The Mrs is out in the S8, she phoneds me a bit panicked and shook. She says there’s something wrong with the wheels on the car, it was skidding. Ok, so were you going fast. No. Ok. I’ll check it. This is after I have stuck the winter wheels back on which are obviously a bit narrower. A lot narrower. Anyway the pressures were a bit off, got that fixed and discovered that yes, it gets a bit slidy - at 50 on a roundabout. Goes back and explains that perhaps she’s got used to driving around far too fast, she says “well there was this Golf sitting too close and annoying me”... I stopped her right there.

Anyway it got me thinking, the throttle response on this motor has always been a bit jumpy - which may have brought on a slide a bit sharper. I put that down to the automatic and the powerful engine at first but now I’m thinking that perhaps the throttle potentiometer has worn down near the start of the pedal travel. I did read that these were early fly by wire motors, and normally the early ones had pot’s instead of hall sensors.

Anyone else had this / replaced theirs / had their Mrs turn into a rally driver overnight?

All sorts of reasons for that. In my case after suspecting the throttle, MAF, F125 switch (which was dodgy) and many other things, it turned out to be mainly a mis-adjusted brake pedal switch! :Confused:

If you do want a throttle potentiometer I have a spare that I never fitted. Bought used from our sponsors.

It's still pretty kangaroo-like when first driving off from a cold start, but settles down quickly. Not sure if that's to do with the SAI system.

Sounds more like your wife's driving style IMHO..however good luck with that one+++

Never had any issues no matter how hard I drive it. Also never mangaged to get it to slide except in snow.

Often on roundabouts there may be some diesel spill from buses, they are prone to filling them till they overflow I noticed, There is a corner near me that has caught a few drivers unaware and the theory amongst locals is it could be down to diesel spill.

In any case get her signed up for next years Monte Carlo..starts from Paisley I think+++

I've had my D2 S8 (well, actually it's now David's S8) on a track on a performance car driving course and it didn't slide at all. But I do wonder what wheels and tyres you've got on as winter wheels, especially as you say that they're much narrower.

Brake pedal switch!? What's that got to do with accelerating? Sometimes motors are bizarre!

I'm fairly certain it's not gearbox related, when you try to pull away smoothly you have to treat the pedal like a Fabergé egg, there's a very definite point where you press the pedal beyond and there's a sharp rise in power, leading me to believe it's worn. The jump is less noticeable at speed but still there.

After releasing it to drive off it sticks in a position (there are actually two separate switches) where the brakes lights are off but the ECUs think the pedal is still pressed, limiting engine power despite a heavy right foot.
Then, vibration or whatever makes the pedal lift a tiny bit more, brakes are now seen as off and the ECU says - OFF YOU GO! Wham! :ROFL:

I was able to prove that on mine by monitoring the switches with VCDS and adjusting the stop (just a twist but PITA to get at!) until they accurately reflected my foot on the pedal.

Just a thought..does she drive with it in "S" mode, that does seem to make the throttle response more "immediate"...:D

It's 18" Avus from an A/S6 - Not sure of width and it's too cold to go out and see!

The jumpy throttle and higher speed is the reason I think it slid, well when I say slid, squirmed. I had to be pushing it mid-corner to get it to go, so completely expected, but a bit disconcerting for her.

They should be fine, but what tyres are they?

I may be talking crap, looks like they are the same width. Dunlop SP Winter Sport 3D, the summers are Conti Pilot Sport affairs.

Then again it has been icy here and damp on the road and quattro doesn't make it invincible!