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Fast idle on startup
Posted: Tue Mar 29, 2011 12:17 pm
by dissolved
Hi all!
I've just bought my first 406, my first French car even and really happy with it. Only problem is that when you start from cold it idles at 1200rpm or so before settling down to a more acceptable 800 or so when warm - just wondering if there's anything I can do to sort it out?
touch wood it seems to be the only thing it does wrong!
model is a 1.8 2000 LX.
Re: Fast idle on startup
Posted: Tue Mar 29, 2011 1:17 pm
by mjb
Could be the coolant temperature sensor's expired?
Re: Fast idle on startup
Posted: Tue Mar 29, 2011 1:49 pm
by dissolved
thanks - i'll renew it at next service if the service itself doesn't clear the problem
shouldn't be more than £20 surely?
I'm looking at using Euro Car Parts unless anyone can recommend a cheaper parts dealer online!
Re: Fast idle on startup
Posted: Tue Mar 29, 2011 1:55 pm
by mjb
I said "could be"... It was just a guess. Before you go spending money on the whim of some bloke on the internet (even if it is me

), I'd check out this thread:
viewtopic.php?f=10&t=7050 and wait to see if anyone else has any theories
Re: Fast idle on startup
Posted: Tue Mar 29, 2011 1:59 pm
by kevtherev
dissolved wrote:Hi all!
I've just bought my first 406, my first French car even and really happy with it. Only problem is that when you start from cold it idles at 1200rpm or so before settling down to a more acceptable 800 or so when warm - just wondering if there's anything I can do to sort it out?
touch wood it seems to be the only thing it does wrong!
model is a 1.8 2000 LX.
mine does the same, always has. start it first thing in morning kicks up to 2k rpm for a split second then down to 1200, after a few mins its idling correctly. more noticable in really cold weather. could be to do with getting the cat up to temp quicker? i shouldnt worry to much ( i dont)

Re: Fast idle on startup
Posted: Tue Mar 29, 2011 3:08 pm
by dissolved
as I said, if the service doesn't clear it i'll look into the sender
at the end of the day if that's all I have to worry about I'm doing alright eh, luckily it seems a sound motor...
Re: Fast idle on startup
Posted: Tue Mar 29, 2011 4:00 pm
by Gary406
how long does it take ? to settle down to 800rpm ?
not sure about petrol engines but dont they have some sort of automatic choke for cold starting ?
my mate has a petrol car next door and i'm sure his revs like yours on cold in a morning.
PS just replaced both my coolant sensors on my 1.9 diesel.
1 cost £29
1 cost £14
Re: Fast idle on startup
Posted: Tue Mar 29, 2011 4:17 pm
by dissolved
it takes a couple of minutes - automatic choke sounds about right. I've probably just asked a really stupid question to be honest - just getting used to the nuances of the car having spent 8 years with one of Ellesmere Port's finest repmobiles.
Re: Fast idle on startup
Posted: Tue Mar 29, 2011 4:20 pm
by Gary406
once the engine is upto temperature does it still do it when you start it ?
Re: Fast idle on startup
Posted: Tue Mar 29, 2011 5:03 pm
by dissolved
not had it long enough to say it's a trend but it seems ok at temperature - with that in mind i'd be surprised if it wasn't the choke.
due for service next month so will be in a better position to say if it's the choke or not after that (also I'll have had the car a bit longer and will be used to its quirks more).
appreciate peoples answers - glad to have joined a community for what seems to be a very nice motor
Re: Fast idle on startup
Posted: Tue Mar 29, 2011 5:11 pm
by Gary406
let us know what happens after the service.
i would think it was the auto choke tho.
Re: Fast idle on startup
Posted: Tue Mar 29, 2011 6:18 pm
by kevtherev
dissolved wrote:it takes a couple of minutes - automatic choke sounds about right. I've probably just asked a really stupid question to be honest - just getting used to the nuances of the car having spent 8 years with one of Ellesmere Port's finest repmobiles.
i was the same mate after 6 yrs of poxhall ownership. different cars do things slightly differently and if you dont know it would seem something is wrong
back to the fast idle issue ive just come back from work and its fairly warm and only kicked up to 1600 on initial start up but will go to 2000 when its cold so i would think its just the auto choke, depending on outside temp how high it revs,
Re: Fast idle on startup
Posted: Wed Mar 30, 2011 7:25 pm
by robb
I wouldnt worry too much my 2.0 petrol does the same .I always thought it was an automatic choke the revving stops when the engine is warm
