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Macbeast - 25/7/12 at 08:14 PM

53 Ford Focus, 1.8 Zetec.
When I pull up, at traffic lights say, come off the accelerator and step on the clutch the engine speed rises from the normal 800 rpm to about 1500. After 2-3 secs, it settles back down to the normal 800 rpm.
Only just started doing this. Any ideas why ?

flibble - 25/7/12 at 08:41 PM

sticky iac valve?

tomgregory2000 - 25/7/12 at 09:25 PM

Broken

Simples

Macbeast - 25/7/12 at 10:56 PM

Great.
Thanks
err
What's an IAC valve ?

RK - 25/7/12 at 11:05 PM

Idle Air Control

Tiger Super Six - 26/7/12 at 10:03 AM

I had an Escort 1.8 Si in 1997 and it did the same thing, never sorted the problem!

Davegtst - 26/7/12 at 10:55 AM

There used to be a few of these causing problems when i worked for Ford. You can try unbolting the idle valve and giving it a good clean out with some carb cleaner. That usually sorted the problem.

Bluemoon - 26/7/12 at 11:46 AM

quote:
Originally posted by Davegtst
There used to be a few of these causing problems when i worked for Ford. You can try unbolting the idle valve and giving it a good clean out with some carb cleaner. That usually sorted the problem.


Had the same problem on our Fiesta (cross flow derived engine), uses the same IAC as the zetec, tried cleaning with carb cleaner still not working; ended up replacing it.. Ours had got stuck open a bit and would over rev all the time.

Come to think off it it showed symptoms like you describe before failing, thought it was a sticky throttle cable.. Once it failed with what amounts to an air leak as so large it was almost un-drivable; In a 7 think it's going to be a brown trouser moment..

[Edited on 26/7/12 by Bluemoon]

mcerd1 - 26/7/12 at 12:39 PM

had the same issue on my 1.8 focus (Y reg) - it was just a massive Vac. leak from a split breather pipe


it was this one in mine, goes round the back of the head and is very hard to see without removing the air intake etc...
breather pipe
breather pipe

[Edited on 26/7/2012 by mcerd1]

Macbeast - 26/7/12 at 05:25 PM

OK guys. Thank you all very much.

Checked Haynes for IAC valve and it says on the 1.8 it's behind the inlet manifold and VERY difficult to access

Deep joy. so what's new ?

mcerd1 - 26/7/12 at 06:42 PM

quote:
Originally posted by Macbeast
Checked Haynes for IAC valve and it says on the 1.8 it's behind the inlet manifold and VERY difficult to access

you can see it once the plastic intake pipe comes off - from memory all you need to do is unplug the mass flow sensor, unbolt the air filter top and remove the jublee clip from the throttle body - you should be able to see it after that

you don't want to touch the manifold or throttle body itself, because then you'll need new gaskets

[Edited on 26/7/2012 by mcerd1]

UncleFista - 26/7/12 at 09:28 PM

If it's the one under the plastic inlet manifold, it's a pain but quite doable by feel.