Self Revving?

[shaneg]

Occasionally (1 in 5 stops roughly), whilest sitting at, say traffic lights, my a3 will rev itself between its idle point and about 1.5k revs up and down until I pull away.

Engine management light is on.

Unfortunately I have not had a chance to get it diagnosed yet due to a busy work schedule but I would like to know what you guys think the problem maybe and a rough cost if at all possible!

Thank you

 

[JD09]

Would suggest it'll be difficult to diagnose without running VAGCOM, that'd be the best bet.

 

[DaveA3]

mine did this a lil bit. Turns out the throttle body just needed cleaning. get some carb cleaner and spray it in and give it a few revs. i took mine out to clean tho as it was easier to get all the crap out

:thumbsup:

 

[<tuffty/>]

Sounds like a vacuum leak and a big one if its caused the CEL to come on as at a guess the idle trim will be maxed out...

VAGCOM and block 032 will say for sure...

Have a look at hoses coming off the bottom of the inlet mani in particular the PCV ones as I would imagine you have a big split in that...

<tuffty/>

 

[Westy]

Also could be the clutch sensor. You'll need to get it on VCDS/Vagcom

 

[shaneg]

Thanks for the replies people, Will take a look tonight when I get home from work at the mentioned causes, if no joy will get it on diagnostics asap