Sorry Munir,
Roy sent me a message in order to translate it for you some weeks ago and I was just too lazy. But here we go:
Before changing any parts, check the idle switch at the throttle valve potentiometer. You find it below the idle valve in the fron of the engine. At the potentiometer your find two cross-drive screws. You have to lose them and rotate the potentiometer until you hear a gentle "click" just before the throttle valve completely closes (use the little lever). When everything is in place, tight the screws, double-check if it clicks and make a test drive.
Still, it is most certain that your engine speed sensor has a defect, it is extremely common. You would find out when reading out the ECU fault memory. But give the idle switch a try.
Regards
Bastian
PS.: In order to use the V8 mailing list, you have to send a mail to
v8@audifans.com - it is then spread to all members of the list.
