Very high idle when cold...

[Paul]

Hi there, have seen your site and am very impressed with all your knowledge and was wondering if anyone could help. I've got a mk1 hgt with 61k on the clock and for the last few months when i fire her up from cold she ticks over at almost 1800 rpm which seems really really high! what could be causing this? and at around 1500 rpm when warmed up i get terrible noises coming from the o/s side. i think the belts may need re-tensioning could that be the case? Cheers

 

[Anonymous]

my first suggestion would be the MAF for the idle, the 147 can run without it (just for checking it out, wouldn't recommend it long term), it will run default map without MAF input.
Safest method is to disconect the battery, negative terminal, then unplug it.
If you ar getting any form of belt noise i'd get it seen to as maximum priority, I've suffered several belt failiure and they can cause extensive damage.

 

[Sven]

The rpms that you mention are OK for the cold, but warmed up it should sit around 750-850 rpm.
IMO the ICV is clogged or not working right.

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[Anonymous]

Thanks chaps! will take a look tonight! It's fine when warm so i'll try cleaning up the maf 1st. That's the one on the air intake after the rubber hosing isn't it?

 

[Sven]

Yes, but the MAF aint the thing that controls the idle rpm.
And FIRST try the car with it unplugged, before you go with the cleaning - you can mess up a good MAF.

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[Anonymous]

Ok cheers Sven! Where's the icv hidden then!?

 

[Sven]

Number 8 on the pic under

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[Anonymous]

Thanks matey. That's very helpful. Will print it out!

 

[Anonymous]

Sorry forgot to ask - is it a case of disconnect the icv and see what happens to the rpm i.e. searching etc...?

 

[Sven]

Disconnect and see, the car should stall, but try to clean it also.
Dont forget the rpms can go to 1800 when its realy cold or for several secs when the car is started

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[Anonymous]

Mine is doing that in summer - for several minutes!!!!!!!! Thanks for all your help will post the outcome tomorrow!