Erratic Revs when starting engine

[JAZZK]

I Have a 1997 MK3 GOLF 1.6 GL. Just recently had a new exhaust fitted (Mid & Rear sections) I have noticed over the last couple of weeks when I start the engine the revs shoot up to around 2000rpm the come down again. It seems to be o.k when I am driving around but when the car is idle the rev counter needle seems to bounce around a bit.
Does anybody know what the problem might be. A mate said It might be the Idle control valve or Throttle control unit. I am not sure where these are located in the engine bay.
Any help would be appreciated !

Thanks

[cara_essex]

Hi,

We had this problem and i believe the name for the bit causing the problem was the throttle positioning sensor, although this is within the throttle control unit, so we had to replace this whole part.
On ours it was situated below the air filter compartment... however once we replaced it we had to get someone with VAG to realign the part as the revs were still funny. Im sure someone can explain this to you further as i still dont understand it!!

I will say though that our fault was picked up on a diagnostic scan, so it may be worth paying the £40ish to get one of them done?

Hope this helped a bit,
Cara

[JAZZK]

Thanks Cara, just out of curiosity was it expensive to fix?

[cara_essex]

The part we had to buy, the Throttle valve control unit, was about £170 then we had to pay about £40 for it to be hooked up to the diagnostic unit so the TB could be readapted to the ECU.

Hope this helps!

[JAZZK]

Thanks for the info. Hopefully I can get it sorted soon, its driving me mad!

Thanks

[adamss24]

Thanks for the info. Hopefully I can get it sorted soon, its driving me mad!

Thanks

Where do you live ? All you might need is just a Throttle Body clean and a recalibration with vag-com ! If you live close to N. London, i can do that for you for 20 quid ! Might save you a good few hundred notes !

[JAZZK]

Thanks for the offer, but I live in essex so not possible to get time to get over to north london what with work and other things. I will take your advice though and see if I can get the throttle body cleaned and re-calibrated to see if that cures the problem.

Thanks for your help.

[lotus_europa]

I Have a 1997 MK3 GOLF 1.6 GL. Just recently had a new exhaust fitted (Mid & Rear sections) I have noticed over the last couple of weeks when I start the engine the revs shoot up to around 2000rpm the come down again. It seems to be o.k when I am driving around but when the car is idle the rev counter needle seems to bounce around a bit.
Does anybody know what the problem might be. A mate said It might be the Idle control valve or Throttle control unit. I am not sure where these are located in the engine bay.
Any help would be appreciated !

Thanks

hi - I have a 1998 TDI engine AHU about 121,000 miles.
When i start the car when it is hot i get the same problem. From cold the engine is fine. I start the car, the engine races a little then runs fine. I will try this fix but am curious as to why my problem only hapen when the car is well warmed through.
I have inspected the soldered joints on the infamous relay 109 because i have had dry joints on this before.
Any thoughts ?

thanks
david isherwood

[admc6]

I have heard a dirty MAF can cause this sort of problem.