Very strange accelerator problem

[psynnott]

I have a 1999 Audi A3 1.6 Petrol. This has now happened 4 times and I would like to know what is causing it:

- Every time it has happened, I have been driving in city traffic, low revs (~1500rpm)
- I would feel a little judder, and then the car would seem to take over control of the accelerator. In gear, the revs would stick around 2000rpm, in neutral it would sit at 4000-4500 rpm.
- I have checked that the accelerator is not physically stuck, the mat isn't getting in the way etc.
- When this happens and I push the accelerator, the car would judder and there would be no acceleration. Lift off the accelerator again and the revs would go back to 2000 in gear/4000 in neutral.

The only way to fix this is to turn the car off then back on again and everything runs fine again.

What would be causing this? The first time it happened I almost went into the back of someone as I wasn't expecting the car to keep accelerating when I was braking in gear!

Thank you

[atkins106]

same thing happened to mine a few years ago...was the throttle body.....u have to buy the unit as a whole, but should cure it

[pyrah21]

Had a friend with the same problem and he changed the throttle body unit to

[psynnott]

Finally got the car into the mechanic and just let him run a diagnostics on the car to see what he could find. First thing he found was:

"020A Temperature sensor coolant open circuit/positive short"

Which I believe is part number 059919501a. The mechanic replaced it today along with the induction pipe from mass air flow (MAF) sensor.

I was having trouble starting the car after turning it off for a few minutes (e.g. popping into the shop etc). Now it starts without any problem at all. It was also very difficult to start after it would rev up by itself, hopefully everything is fixed.

The sensor cost me £22, induction pipe was £34, Labour was £45.

Will keep this thread up to date with results in about a month.