A3, AVU Engine - Unstable revs (Fly by wire throttle)

[oweny]

The fast idle on this engine is unstable I cannot maintain the revs at 3000 to carry out fast idle emission test for NCT the car gives no trouble on the road with this problem but will fail test when held at 2000 revs it will creep up to 4000 and will not reduce to 3000 and as you reduce pedal movement it will fall back to 1500 and will idle ok and test ok at idle there are no codes present .
In measuring blocks how would I interput the pedal control and the trottle body to determine which one is at fault if I am going in the right direction .
I would be greatful for any input .

Regards Owen

[Angus]

Owen

I've had exactly the same [even the same car and year.]  It's not a fault, it's just a feature of the software.  When the vehicle is stationary, it won't hold a steady throttle.

Get your tester to contact VOSA; they're fully aware of this problem and allow a special dispensation to test the affected cars at over the recommended 3,000 revs.

[Crasher]

The MOT station should be able to ask the ministry for conformation on this, it is a regular VAG issue.