Sticky idle air control

[Chilli Girl]

Well, thought I'd post in right section today about Sapphire's high idle. Ok, so I've just taken her out for 20 mins and the revs are now showing 1200 at idle when warm so it's coming down opposed to 1500 yesterday. I decided to rev her whilst stationary when warm obviously  the rev counter shot up but came slowishly back to 1k but then hovered upto 1200 then settle eventually at 1k so not quite as bad.  Are we still thinking sticky idle control?    Foxy ended up with a new iac in 2016 when her revs were behaving the same!   

[Gibla]

new iac

I'm going to do a @Joesson here Jane

iac?

idle air control (as in the title) doh!

[Dev]

You can try something simple that has worked for me. Remove the intake hose and use some MAF sensor or intake cleaner and spray it in the hole that is just before the throttle plate. This will add solvent and loosen up the gunk that is biding the IAC from moving its full range or if it is slow to respond. 

Give it some time for the solvent to work and evaporate then repeat once more. After starting the car the IAC should fluctuate and then settle down to the correct idle after a good drive it might fix it.

Before you do that I would spray intake cleaner around the vacuum hoses and see if the idle is raised. If it does raise then spray on individual hoses and to find any cracks in the rubber.

The last thing to try is to make sure the throttle rotor snaps back without any biding from the cable. Observe that the throttle plate is fully closed.

[Carolyn]

Yes it does seem to have all the symptoms of a sticky (wait for it Gibla....

IDLE AIR CONTROL VALVE!!!!

It might just settle down on its own.

[Chilli Girl]

I'll take it to work on Mon and Wed, (8 miles) and then I'm off to Mum's on Wed evening (60 miles) so that it'll be a good test for it. Loving being back in her, I've missed her.

[Gaz mr-s]

Also worth a try is burping the radiator when it's hot. Pop a few of the frunk clips on right side & lift the corner up to get to the valve. If you get a good belch of air, repeat the process. And keep an eye on the coolant level.

[Chilli Girl]

Yes it does seem to have all the symptoms of a sticky (wait for it Gibla....

IDLE AIR CONTROL VALVE!!!!

It might just settle down on its own.

Right again @Carolyn, idling at 1k this am when warm & it was a frosty cold am so sticky iacv must've released itself. She went like a dream & made my Monday morning commute so much better. Happy Bunny this am. Yeh!

[shnazzle]

Yes it does seem to have all the symptoms of a sticky (wait for it Gibla....

IDLE AIR CONTROL VALVE!!!!

It might just settle down on its own.

Right again @Carolyn, idling at 1k this am when warm & it was a frosty cold am so sticky iacv must've released itself. She went like a dream & made my Monday morning commute so much better. Happy Bunny this am. Yeh!

Those things are  a pest.

Not much you can do about it either other than staying on top of air filter maintenance.
Even frequent spraying of solvents to dissolve gunk would ultimately wear away the grease in it and make it seize completely.

[JB21]

Mine was sticking on the new 2ZZ engine. 2k rpm idle, and the dead give away for a sticking ICAV is when on the move you dip the clutch and the revs fluctuate. This is now starting to settle down, but its still not perfect. Need to do the clean procedure as Dev mentioned above. If that doesn't work I'll whip the valve off and get it cleaned up properly by removing the solenoid and rotating it by hand. Its a bit of a faff to remove as its right at the back of the TB and coolant pisses out of the small lines.

[Dev]

Yes it does seem to have all the symptoms of a sticky (wait for it Gibla....

IDLE AIR CONTROL VALVE!!!!

It might just settle down on its own.

Right again @Carolyn, idling at 1k this am when warm & it was a frosty cold am so sticky iacv must've released itself. She went like a dream & made my Monday morning commute so much better. Happy Bunny this am. Yeh!

Those things are  a pest.

Not much you can do about it either other than staying on top of air filter maintenance.
Even frequent spraying of solvents to dissolve gunk would ultimately wear away the grease in it and make it seize completely.

From my experience and others I believe it is an air filtration issue. It is caused by those gauze oil performance air filters that allow dirt and oil mist that comes off the filter to gum up the IAC valve. This is what causes frequent cleaning.
   My other cars use the OEM panel air filters and not one problem even after over 100k miles but if you go on many forums where enthusiasts first mod is an air filter that is when you have both MAF and IAC issues.  When removing the IAC or MAF you can physically see the build up however when its on a car that uses paper filtration its is much cleaner or in my case after many thousands of miles very clean.  With the paper filter it actually becomes more efficient at trapping dirt as it gets older so there is not much chance if you are late with maintenance but you will suffer performance and fuel efficiency issues.

The previous owner of my 2ZZ engine used an oil gauze filter and I did use it for a little while with issues from the IAC but it was drivable and thought I would eventually replace it for a new unit. Once I changed to an oil less foam filter and cleaned the IAC using solvent the problem went away and then years later I replaced my entire intake with a new one that came with the oil gauze filter and the problem came back.  I changed to a performance synthetic paper filtration that I have currently  and I never had a problem after that including the MAF sensor which remains clean.

 What I am getting at is frequent cleanings are not necessary if you solve the issue with filtration however the IAC valves do have their own inherent failures types like dirty electrical contacts and tired motors which do need actual replacement but it is worth inspecting and cleaning them first.