After fitting my dump valve yesyerday I have noticed that when the car is first started the revs seem to sit above 1K, where before it never used to. After driving it for a bit, when the car comes to idle the revs stay at about 800 which is what I usually idle at. Is this normal or hve I got a prob?????? I went to the dealer today but he said he can't look at it for a week or so :thumbdwn: So has anyone in the Wigan/Greater Manchester area got VAG COM??? If so would you be ever so kind for me to make my way to you to have a looksy??????? Or if anyone has had an experience of this please share as I am confused as the car drives fine etc it's just at start up.

Oh hang on as well I noticed what sounds like a sucking noise at the back sorta round where the turbo is when I had a looksy under the bonnet while I was leaving it to cool down is this normal (haven't done that before)????? Cheers all

Rich

When I start my car up from cold it idles at 1300ish revs. It soon drops to 800ish though.

Steve

I've just never seen it do this before that's all so am a bit concerned (i'm like a big baby with my vRS toy)

You're probably a bit more attuned to what's happening because you've just fitted the new DV Don't worry, it's perfectly normal for the engine to idle a bit faster when it's cold.

It took a long time for me to get used to the various strange noises on startup - once I understood them they weren't a problem:-

• "Diesel" noise on turning the key - caused by the hydraulic tappets taking a fraction of a second to pressurise.
  
• "turbine whine/blowing exhaust" - caused by the secondary air injection system blowing air into the exhaust stream while cold (burns excess fuel, preheats catalytic converter).
  
• Fast idle - AIUI, common to all (petrol) cars
  

KLB you are a star Cheers for that. My problem is that I haven't driven the car for a while as I don't need to drive to work, and I haven't really had the need to go out in it :( So new noises jump out a bit more as I don't hear the car running as often as most people do. Anymore input is appreciated though

One thing worth checking is that there are no air leaks - either from the DV or associated pipes - this would upset the engine controller causing the engine to behave differently.

As KLB said, it's normal for the engine to idle faster when its cold - stops it stalling as the fuel and air don't mix so well when the engine is cold.

Just for information, my engine started idling at 1500 rpm even when warm, which was traced to a faulty air temperature sensor.

This is normal, i think the revs are above 1000rpm when the engine is first turned on because the oil is thick, as the oil warms up it gets less viscous hence the decrease in revs? am i right or totally wrong? or is it a bit like an auto choke?

The start up revs drop suddenly from 1400 to 800 it must be a ECU function rather than internal friction. This would give a more gradual decrease.

Steve

All petrol engines need a richer mixture and a higher idle speed for starting and the first few seconds afterwards. Once warm, the petrol vapourises better, and less is needed. Also as daytripper suggested, it's important to get the oil circulating as quickly as possible. Actually the viscosity will decrease with temperature, making it easier to circulate, not harder, so this is not the cause of the increased idle speed, rather one of the factors influencing its presence. This used to be achieved with a choke, nowadays the ECU performs the same function, and is able to react much quicker than a mechanical choke to the changes in temperature in the engine.