joel91

okay i have a rough low idle and i think this may be my problem. I read a thread a while back to spray starter fluid into the acv inlet and the idle shouldn't change...but it stalled my car(must be a big leak!!).
So i want to know a couple things. Is there any fix for this like replacing a valve inside the acv or anyway to unstick it??? If not then does anyone have a picture of the two holes that you can rtv shut to solve this leak?? And by running my car like this can it hurt the engine??
Thanks

joel91

Damn, mazdatrix wants $360 for an acv...anyone know where i can get a cheaper one?? Probably want to stick with a new one because of the trouble that so many of them have.

blazer1313

No one replaces those. We just take off the valve and put on a block off plate. $12

joel91

yea but i have emissions where i live...so the acv is not repairable then right??

HAILERS

It's probably the internal part of the ACV that is called the ANTI-AFTERBURN VALVE. If that is the case you can repair it yourself with some black RTV.

The ANTI AFTERBURN VALVE in the ACV is the only part of the ACV that can inject air into the INTAKE MANIFOLD. It should do this only when you have been on the throttle and then let off the throtte, It lets air into the intake manifold (small amount) to prevent backfiring. If this valve is old and leaking, then it will result in an irregular idle. Once you fix this problem you can expect the idle to be DIFFERENT due to the change in the amount of air injected during idle. The idle will then have to be adjusted for this change.

What you do is remove the ACV. There are two SMALL holes that need to have some black RTV kneaded into them. One hole senses a vacuum during deceleration and the other a air feed hole to the intake air. Let the RTV setup while you reinstall the ACV. I'd wait about two hours for it to set up enough prior to re starting the engine.

I posted a picture twice in the past of which holes on the ACV need to be stopped up with RTV. They're out there somewhere.

A car will pass emissions just fine and dandy with these two small holes plugged.

joel91

ALRIGHT! thanks hailers, ill see if i can find that picture of those two holes you described. But by pluggin those holes will that cause the engine to backfire?? oh and will i need a gasket or is the old usually reusable??

vaughnc

...

HAILERS

here

Houstonderk

iTrader: (3)

Hey so when you have a blockoff plate do you put the rtv in the intake manifold or just the plate?

HAILERS

You just make a gasket for the plate. You don't put RTV in the manifold.

joel91

just to clarify things... i put rtv in the right holes let it set overnight and put the acv back on... i still notice an rpm difference when i spray starter fluid into the acv inlet but the car doesn't die anymore...it is the hose that connects to the air box at the top, then the hose goes down to the air pump right then to the acv right???

HAILERS

That is odd. The only passage in the acv to the intake is thru those two holes I showed. I have no explanation for the revs picking up.

I can't believe anybody would spend eleven bucks for a piece of metal as small as a blockoff plate. (this is not related to the thread owners problem, just a remark).

joel91

my car is an S5, Hailers do you have a picture for the holes to rtv for an s5 acv....mine seems a bit different then the one posted.....thanks

HAILERS

My bad. That was a series four TurboII. I have no series five, BUT here is a jpg of a series four NON TURBO. The red RTV is in the appropriate holes.

Let's say your's lools a touch different for a series five. I assume your manifold has two small nipples just above the acv. Those nipples are for the Relief and Switching diaphrams in the acv.

If you attach a piece of vac hose to each of those nippes and blow, you can see where the exit hole in the mating surface of the acv is for those two nipples. You DO NOT want to RTV those two mating holes in the acv. Sort of a lesson in what NOT to block.

The Anti After Burn holes are the Small holes your left with on the mating surface of the acv. Those two should be blocked. They're the only two that can leak air to the INTAKE.

If this makes no sense and the jpg does not match yours......let me know and I'll try harder. P.S. Be sure to get a drill bit/whatever, and remove what you now have blocked up.

REMEMBER, in that jpg there is a gasket attached to the ACV mating surface, so don't let that fool you. You can barely make out the impression on the gasket of the cutouts in the manifold. I more or less attach the gasket to the ACV then when installing put a film of RTV on the mating surface of the gasket. That's so when I remove the ACV it comes off cleanly and does not rip apart the gasket.

Syonyk

You could just buy a new ACV from someone. There are a lot floating around (as a result of people getting rid of them).

-=Russ=-

joel91

thanks hailers.... i pulled the acv back off and sure enough i rtv'ed the right holes according to that s5 schematic. i checked the gasket for the acv too, nothing torn or anything. yea i still don't understand why it would change the idle still by spraying starter fluid into it???
at least it doesn't kill the motor like it did before. oh by the way I WAS SPRAYING INTO THE UPPER MOST HOSE THAT GOES TO THE ACV DOES THAT MATTER??
THANKS...AGAIN

HAILERS

Nope. I've no idea why the rpms change when you spray the starter fluid. Unless my mind is stuck in a rut, only one of those two passages can actually let the starter fluid into the INTAKE.

The other holes lead to ........the exaust ports at the mating area of the exaust manifold and the exaust header(just inside that mating joint), that would be the passage thru that spoked looking checkvalve..........and the other hole leads to the Split Air Pipe to the catalytic converter. Neither of these lead to the INTAKE.

You said the gasket is sealing good so that can't be it. I'm at a loss.

Closing off those two holes like you did should result in a bit better idle now that you don't have that unauthorized air leak to the intake.

On the ones I blocked off I didn't even put much RTV into the holes. Just enough to stop any leakage. Maybe I need to revisit my car and do a little spraying to see if the idle is effected in any way. I should'nt Puzzleing.

Make sure that after you reinstall the ACV that you can take a piece of vacuum hose and attach it to each of the two metal nipples just above the ACV, and when you suck on the hose that you can hold a vacuum on that hose. IF you can't it means a diaphram in the ACV is busted. That problem is ALMOST impossible to fix. In that case you'd be better off trying to aquire another used/new ACV. I batted fifty, fifty on buying a used one. One good, one bad.