Re: [TECH] Auxiliary air regulator....Need info on failure....can it be bypassed?

[Nigel Heron <scirocco@psycode.com>]

"Paul J. Dorion" wrote:

>  I got the tune-up, shocks and all the goodies done on my rocco on
> monday, it worked great... til tuesday morning. My timing belt broke,
> so I replaced it the tensionner and the valve cover gasket. When I was
> done and the timing was verified, I noticed the car had a very erratic
> idle, I decided to take it out for a spin to see if a little drive
> couldn't clear up something like a blocked injector or something, this
> effort was in vain. I however realized that not only the idle was
> erratic but that my roc was stumbling severely when the engine was not
> under load (when maintaining a speed , under 3000 rpm in any gear).
> Acceleration is not a problem, and speeds that required engine RPM's
> above 3000 are ok but anything else was hell.. I was told my Auxiliary
> air regulator was toast, why would it screw up right after a tune up?
> does the timing belt going have anything to do with this... can anyone
> explain the purpose of the Aux Air regulator in a nutshell?

the aux air valve is used to give the engine extra air at startup and
for a few minutes more on a cold engine. To check it simply pinch the
hose going from the aux air valve into the intake manifold (it's on the
passenger side just behind the 5th injector), if the engine is cold your
idle should drop and the engine might stall, if the engine is at
operating temp the valve should be closed and pinching the hose should
have no effect on the idle.

I can't see that having a bad aux air valve could cause your problems,
since the air drawn through the valve has been metered by the air flow
sensor and the extra fuel is being delivered. It should just give you a
high idle, say around 2000 or so. It wouldn't cause an erratic (up-down)
idle since it takes a long time for the valve to open and close.

maybe you should check your belt timing and ignition timing again just
to make sure it's not a bit off. Also check for any vacuum leaks or any
disconnected hoses since the valve cover was removed.


-nigel.
86 Scirocco
85 Scirocco
http://scirocco.psycode.com/


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