High Idle

[Tallulah]

Hi, I have a little problem with my idle. Normally when I start the car from cold the idle is around 1000 rpm then as it gets warn it settles around 680 ish but the last week or so after I have been driving about 20 mins when I come to a stop it idles at 1000 even though its up to temp?? When I get home and turn the car off, if I turn it straight on again it goes back to 680? Any ideas? Thanks :)

[touranasurus]

HI, you need to plug vagcom in to see the codes, could be the temp sensor. Have know things like air-cleaner needs changing, good luck.

[Crasher]

Could need a throttle body clean and reset but get someone to do this who has the equipment to reset the learnt values and basic setting, I have known AUS engines go a little loopy after the throttle body has been cleaned and then they start showing EGR and MAP sensor faults.

[Tallulah]

Vagcom found no faults, throttle body was cleaned back in april when the top part of the engine was removed to fix burnt exhaust valves, not sure if it was adapted back but has been running fine until now, is it too late to reset the values, as I know it's clean, only been running her on bp ultimate since all the work. Thanks :)

[Crasher]

The learnt values can be erased at any time, the one caution is that deleting them on the AUS and BCB engines can make the ECU go potty and throw up MAP and EGR fault codes and getting them stable again is not a set procedure and replacing the MAP and EGR will not help.

[Tallulah]

Ooh that doesn't sound good! Am I best just to leave it then? Will it do any long term damage? Sometimes whilst i'm driving it settles back to 680 after a short while.

[Crasher]

If they go into this strange mode and the person working on it does not know what to do, it can cause trouble. The first time I had it happen it took hours to work out how to make it behave again and that was after fitting new parts that ultimately were not needed.

[Tallulah]

It was my altenator regulator! After a couple more days the idle was high but all the time then my abs light came on and then after I had parked up it wouldn't start (flat battery) so called out RAC to jump start me as I was stuck in Asda car park! And when I re-ran the diagnostic, there was the fault. So 1 new altenator later and car is back to normal :)