A4 start up revs

Honest John Back Room » Technical matters
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Fri 17 May 2002 21:57
A4 start up revs - jud
I've just had a 2 year service carried out at a Audi dealer.
Since then when i cold start the engine i get a half second increase in revs to around 1200rpm. It never did this before, the only difference there is from my previous service (this time last year) is the use of fully synthetic oil as opposed to semi , any ideas before i contact the dealer? , he's a inconvenient 15 mile away.
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Sat 18 May 2002 08:21
A4 start up revs - Adam Going (Tune-Up)
Jud,

Can't claim any specific experience with the A4, but most engine management systems do (should) provide an initial increase to about this sort of engine speed on start-up, before settling back to normal idle. It is to clear any residual fuel that might otherwise cause a plug to foul for a moment, and to ensure the alternator kicks in straight away. May be that they have cured a fault you didn't know you had !

Regards, Adam
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Sun 19 May 2002 09:22
A4 start up revs - blank
A theory:
If the new synthetic oil is thinner at low temperatures than the standard oil, then there will be less drag, which will allow the engine to spin faster on the starter. This will also mean less friction when the engine fires, so the rev blip, which Andrew Morey mentions, may be to higher rpm and more noticable than before.

That's my guess anyway

Andy
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Sun 19 May 2002 09:23
Oops - blank
Oops. Not Andrew, but Adam. Sorry
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Mon 20 May 2002 07:09
A4 start up revs - jud
Thanks for your comments, it's all very strange but the car now starts as it use to, up to about 1k then quickly down to around 850rpm
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