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idle control air valve

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idle control air valve

Postby michaeltburke » Thu, 20 Feb 2014 7:43 +0000

Hello again
Was having trouble with idling ..may be the idle control valve under the air intake to the throttle body,. ran some carb cleaner through it but revs still hesitate before returning to idle at 850. I was wondering what the effect of removing the electronic connection from this air valve set up...ie would it isolate this function.
thanks
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Re: idle control air valve

Postby franksm » Thu, 20 Feb 2014 8:51 +0000

You could try it, it's a reversible action, but I think it will cause the car to go into open-loop/limp-home mode which means it runs a bit richer = poor fuel economy and a damaged catalytic converter :-(

Try this article - it shows how to measure the electronics with a basic multimeter, and how to clean everything. I will do the same soon myself, the idle is "okay" but not perfect http://www.miata.net/garage/isc.html
It's a small world after all. It's a small, small world
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Re: idle control air valve

Postby michaeltburke » Thu, 20 Feb 2014 11:41 +0000

Thanks for reply. This system seems to have more function than just a traditional choke would have it would seem. Its a messy setup really and it would be great to bypass it. However I have a feeling that this is too easy and that you may be right on the fuel economy opinion.The spector of slow return to idle is a real headwrecker !
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Re: idle control air valve

Postby [L'e$kro] » Mon, 24 Feb 2014 2:55 +0000

There are several things that can possibly give your result:
-Sticky throttle cable
-The "dashpot" damper that dampers the throttle movement when you lift your foot off the throttle. Check if it runs better without.
-The additional air tray actuated by coolant, on the top of the inlet. It's like a thermostat that allows more air in the engine when cold. Not sure it exists on 1.8 engines.
-The idle valve below the throttle body. If you want to disconnect it, also plug it as it may stay half open. Instead of disconnecting it, you can also just put a wire in the diag box like if you were adjusting timing.
Nico
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Re: idle control air valve

Postby michaeltburke » Mon, 24 Feb 2014 6:19 +0000

I think you mean jump 10 and GRD permanently and that disables it ?
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Re: idle control air valve

Postby [L'e$kro] » Mon, 24 Feb 2014 8:36 +0000

Yes, TEN and ground, as per Steve's excellent link, but not permanently, just for troubleshooting.
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Re: idle control air valve

Postby michaeltburke » Tue, 25 Feb 2014 6:29 +0000

Thanks for the reply.
I eventually removed the air control idle valve. A bit fiddly but a reasonably doable job. It is apparently a sealed unit and I didnt try to disassemble it, just gave it a good dousing with carb aerosol. Reassembly is reasonable though water hose crimps were embedded in their hoses after 24 years and I had to have a few jubilee clips ready to replace them.
The result... well the idle needle goes back to its original position wihout hesitation and there is little difference between jumped idle and unjumped idle now . Before , there was always at least 300 revs no matter what I did. So thats my storey...probably worth the efford .
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Re: idle control air valve

Postby Steve » Wed, 26 Feb 2014 11:36 +0000

nice one, did much dirt/oil come out of it?
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Re: idle control air valve

Postby michaeltburke » Fri, 28 Feb 2014 12:46 +0000

Steve - no not really. There was a light carbon layer but almost disappointingly no great deluge of gunk came out. Previously I had sprayed aerosol cleaner into its intake , the s shaped one connected to the main air inlet, while the engine was running . This may also have dislodged some grime at that time. Still ,theres satisfaction in having done it as it was evidently not done before after 23 years an 80 k miles.
.
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Re: idle control air valve

Postby Yolo » Fri, 28 Feb 2014 12:54 +0000

I have a bit of an idle issue and plan to hunting soon so would welcome any pics of what you took apart and sprayed just to point me or anyone else in the right direction... Thanks
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Re: idle control air valve

Postby michaeltburke » Wed, 05 Mar 2014 5:51 +0000

Yolo -Did I not reply ..send me your e mail and Ill sort you with a pic or two....uploading to this site is a job for anothe time
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