Make sure it comes with an o-ring. I believe it's needed to keep air from being pulled in/out.

 

Yeah i noticed the o-ring when i was looking at these. Did not realise it was meant to have one.
mine does not have one……

that could be part of my issues.
guess we will see

 

You wouldn’t need anything exotic, like viton or anything, just something to help seal the air.

 

Around the beginning of my Jaguar adventures, I once had an IACV fail. the engine seemed to run ok but would rapidly become unstable at idle and had trouble holding steady revs while driving.
I had a used spare, so switched it over and things were fine again, although I wonder if a new IACV (and hopefully good) replacement would make much of a difference to idle.
What are your experiences of replacing with a new IACV?

 

IACV is literally idle air control valve.
when the car is under 3km/h is when it takes over.
the idea is that it opens and closes the correct amount to maintain a steady idle speed.
too far closed and car will stall.
too far open (i suspect mine is) and car idles too high.
when moving the IACV should have little to no impact as it will remain in a constant position.
and it supplies such a small amount of air (just enough to maintain steady idle) that it pales in comparison to what comes through when the TB is open

that is my understanding of how they work.

 

just took mine off to put o ring, and i noticed on mine is a metal washer in place where o-ring would sit. i assume this is compressed to buggery and not sealing anymore. will replace with rubber o-ring now and see if there is any difference tommorrow.

and the paper gasket is obviously no good anymore. not sure that the iacv i bought comes with one tho.
suppose a small amount of rtv will do the job

 

ok, so i got my china special IACV today,
mow before i replace it i just wanted to ask,

my original on the car is fitted with a paper gasket and has a metal crush washer.
both of which really should not be used again.

the china special i purchased comes with a rubber o-ring, which will go in place of the metal crush washer,
now in regards to the paper gasket, should i get a shop to make me one up?
should i just dry fit it?
or use a little RTV?
i am thinking a little RTV will do the trick nicely.

 

I bought the same valve for mine just a few weeks ago. Same dilemma

In mine there was a spacer that goes into the throttle body (even is mentioned in the service procedure), then the green gasket, and then the throttle body. But the aftermarket came with an o-ring and a gasket

Upon installing the spacer, the gasket from the kit and the o-ring, the valve actually bent at the side flaps!

I removed the o-ring. Bent the taps as straight as I could. Used an OEM gasket that I had bought earlier with the metal spacer. Didn't use the o-ring or the gasket that came with the kit

 

BTW-you can check if the valve works by connecting it to the harness and turning on the ignition (don't crank the engine...I suppose even if you do, there is no harm done). The piston will retract and extend if everything is working...in my case the old valve's piston had broken in two so I had no choice but to replace it

 

i feel mine is not working correctly. it does move but doing this will cause it to unwind fully.
i believe it may be opening and closing but seating itself in the wrong position.
so for a cheap part i thought i may aswell try a replacement

 

The o-ring (assuming it's the right size, not too thick) should be the only seal you need. If that does it's job, no need for a paper gasket...except maybe as a spacer?

 

The spacing aspect is probably important if the IAC valve seat is only scheduled down to one poppet seat gap dimension and the result determines the idle RPM

The ECU probably does not have a fixed idle RPM target and the engine's regulation devices and their proper operation determine the proper idle speed

If the ECU had a fixed RPM then it would regulate the devices to satisfy the fixed target idle RPM

This idle aspect probably has nothing to do with your upper RPM range short term fuel trim and your fuel economy, but it does square up your engine

There have been cases where the gasket has been missing but I can't remember their issues or results as a correlation

Someone recently cleaned his EGR valve and recovered his idle to more what he liked , There is a EGR _ ERROR parameter ID and the target is 0 through all ranges of RPM as the EGR does have a position sensor as a follow up verification

At idle the EGR follow up position sensor value is 0.70 volts DC on the Red / Pink color wire , the EGR should be closed

The EGR temp sensor value is 4.9 volts DC at idle on your Red / Brown color return wire to the ECU at idle

 

AU market has no EGR.

so what I have done for now just as a trial, is fitted my existing IACV without the gasket and with the rubber o-ring in place of the metal crushwasher.
we will see what happens after i take it for a drive, but initial start up (cold start) had the idle sitting around 850 instead of where it was before at 1200.

i did fit the new iacv and test it, when started the revs went to 2000 rpm, then on a second start they went to 1600.
so if this test does not go well i will put the new one in and see how it goes after a nice drive.

 

ok, so,
i was driving it today, and the idle returned back to the high idle i have been suffering.

so this indicates to me that the IACV is working correctly.
so i have two options as far as i can tell.
1 is vacuum leak
2 is that the iacv is getting the wrong info and the car is thinking it should be idling faster.
this would be fixed by a engine setup thingy which i will get done when i eventually get the car in to get some work like the crank seal done.

 

Yes.

Vacuum leak or Throttle Potentiometer needs to be reset.