Weird fast idle when cold

[Deev]

Just recently (maybe related to the hot weather?) although not every time, when I start up my Leon TDI 110 (02 plate - 49k, quite recently dealer serviced) the idle will sometimes rise to a steady 1100 rpm approx where it will sit for anything up to about 30-40 seconds, then return to it's usual 950ish rpm. Sometimes if I blip the throttle it will make it drop back to 950 straight away. Sometimes when it's at 950 and I blip it will jump up to 1100... Doesn't always happen straight away either. The engine can have been running for a couple of minutes normally then the revs rise...

And all this only happens *sometimes* - no pattern that I can really see, except that it only does it when the engine is cold, and it hasn't done it before now...

At first I thought it may be related to the aircon - ie over-compensating for the increased load - but it has done it even with the aircon switched off...

Very confused... any ideas?

 

[ianc]

My LCR has always since new started at about 1100 and dropped to 700 after a few mins.

 

[Deev]

Petrol or diesel though? I would expect it from a cold petrol engine but don't diesel's work differently? My TDI has always idled at around 950rpm from cold for the previous 18 months of ownership!

 

[Deev]

Just to update, it did it again last night on my way home from the gym. Started from cold (well - it has been standing for about 90 minutes in the car park) and it idled happily at it's normal 900rpm (that's more accurate - I over-estimated at 950!). Drove it from the car park and down the road for a couple of minutes and stopped at some traffic lights. Idled at 900rpm for a few seconds, then it gently crept up to 1100rpm where it sat for a mere 2-3 seconds before gently dropping back down to 900rpm.

It was only about 15 degrees last night, so I doubt it's a temperature thing. And I definitely didn't have the aircon on.

 

[Deev]

Gah... still doing it occasionally...

*vague last-chance bump*

 

[Deev]

Okay sorry to bump this again, but in the past week my car has started showing this problem again, and a little more frequently than usual.

Has noone had this issue before? I'd kinda like to self-diagnose a little rather than ask my stealer next time I'm there in a couple of weeks, seeing as they're going to relieve me of over 500 quid as it is...

 

[rob - 73]

Kinda similar to what my 1.8t cupra has started doing after its service. On cold start up it is up at 1100rpm and is very noisy (tapping) then drops down to the usual 800-900rpm range and is a lot quieter. Any joy when u went to the dealers or any ideas guys?

 

[Hmans3]

My TDI110 has also just started doing this any thoughts to why?