Ferrari Mailing List: Re: Auxiliary Air Valve

[Todd Walke (racertod]

Rick wrote:

> I have since placed the AAV in the freezer at about 25 degrees F, for more 
> than an hour.  The diaphragm should be 100% open - and it isn't.  Here's 
> how it looks at 25 degrees F, http://www.aubard.us/Mondial/HPIM1346.JPG 
> .  Its open no more so than at 59 degrees F!

        I checked my copy of the "Bosch Fuel Injection & Engine 
Management" reference book for info on testing the AAV.  Basically, on a 
cold engine pinching the AAV hose should drop the idle (electrical 
connector unplugged).  Pinching the hose on a warm engine should have no 
effect on idle.
        If the cold engine test doesn't produce a drop in idle speed, the 
book says: "When cold (about freezing) the valve should open as shown in 
Fig 6-2.  If not, replace the valve".  The picture it shows of a 
frost-covered AAV is this: http://web.newsguy.com/racertod/aav.jpg
        Your AAV looks like it opened about as much as specified.  Also 
note the Bosch part number on the photo - same as yours.  What a coincidence!

        My dear, departed Golf with CIS-Lambda never ran at a fast idle 
when cold.  When she was new the AAV was faulty and a cold start in cold 
weather meant an idle speed of 500rpm unless I used the gas pedal to keep 
the idle near normal until the engine warmed up a bit.  After replacing the 
AAV, she would cold idle around the normal hot idle speed of 900-1000rpm.
        Personally, I don't know that lack of a fast idle when cold is 
that big of a deal.  As long as the AAV keeps the cold idle near the normal 
hot setting, I'd call that good.  My VW manual doesn't mention anything 
about a higher than normal cold idle speed nor does the Bosch manual.


Todd
Seattle,WA
'86 GTI, Red of course. (exciting racey car) 268,000 miles
'01 Golf TDI, silver.   (new work car)       189,000 miles
'87 Golf, Polar Silver. (retired work car)   654,000 miles <- Gone to a new 
home :(
http://www.pureluckdesign.com <-Ferrari & VW stuff