Aux air valve questions

[patkeefe]

I posted this in the Tech Forum, but maybe someone here can help a bit. Do 930's have AAV's?
Pat

[sand_man]

Yes. Of course I ditched this little gem along with my AAR ages ago!

[930LDR]

I have heard that removing / bypassing these can make the car run better. Anyone have any instructions on how to do so.

[patkeefe]

Well, I decided to ditch the AAV. I am keeping the AAR, as that does keep the idle up when cold, and it functions as it should. I'm still thinking about how the AAV affects warm start, as Brian alluded to in the linked post. I basically took Bosch's word for it on the warm start issue. So, the AAR now becomes the sole survivor of the ancilliary air devices on the SC...the AAV, decel valve, thermoswitch, and whatever other crap I deemed unnecessary is gone.

I would like to see a schematic of what 930's had, for reference, if anyone has one.
Pat

[JFairman]

I know AAV is the auxilliary air valve that lets air bypass the throttle body to raise the idle during cold starts, and the WUR is the warm up regulator... but what is an AAR?

Only advantage to removing the AAV is loosing a tiny bit of weight... it won't make anything run better when warmed up, and the idle will be painfully low during a cold start without it.

The WUR is a major part of CIS so you can't remove that.

Is the AAR just another casual name for the AAV?

[patkeefe]

The AAR (auxiliary air regulator) is the electrically powered valve which is open when cold, and allows extra air to bypass the throttle. When it gets warm, the sliding disc in it closes the opening, and shuts off the bypass air. In my car, it keeps it from stalling when cold, so it is worthwile to have.

The AAV (auxiliary air valve) is a disc shaped thingy, which is plumbed in parallel to the AAR. From what I've researched on it, it closes at approximately 5" vacuum. It was put in theoretically to assist on warm start when the AAR is closed. Someone has suggested "right foot" as a viable alternative...I'll go with that!

As my car started life as an n/a 3.0L, I am blowing through devices that were meant to get sucked through. I have had intermittent long decel problems in the past, as though the decel valve were still there. Maybe this will fix that.

Pat

[JFairman]

OK, thanks for your descriptions.

I'm familiar with the high idle throttle bypass device on CIS and L-jetronic, and always called it an auxilliary air valve.

If your description is correct, then there is no AAV on '87 930 K-jetronic.
There is a large 3-4" diameter gold cad plated vacuum operated valve thing that looks alot like the one in the picture in the other post link but it is called a deceleration valve on an '87 930.
It is activated by manifold vacuum at the same time as the recirculation valve that recirculates boost pressure back to the inlet of the turbo when you lift the throttle quickly, while the deceleration valve does the same thing between the the intake manifold and the airbypass housing to cut down on the amount of air sucking down on the CIS metering plate.
Anotherwords it leans out the mixture to a degree on deceleration to lower emissions, use less gas, and maybe cut down on popping and flames coming out of the exhaust while decelerating.
The car will run fine without it, but will use more gas on deceleration.

[spuggy]

"I would like to see a schematic of what 930's had, for reference, if anyone has one."

Here you go Pat. The RoW has a couple less parts on it...

[RarlyL8]

The AAV is buried in the back of an SC but is located more forward and on the passenger's side of a 930. The AAV and decel valve look very much alike. The visual diference is that the AAV has both vac ports on one side while the decel valve has ports on both sides.

I removed these devices from both my SC and 930 with no ill affects. It is reversible but a pain to get to on the SC. I will say that if the AAV was working properly before the turbo addition then you may as well leave it in. Mine were removed to simplify the engine and because the AAR was not working optimally.

[patkeefe]

Thanks Andy!!