Re: Air leak (88, audi 90)

[allanm@PrimeNet.Com]

//--- forwarded letter 
-------------------------------------------------------
> From: "David Bokaie" <David_Bokaie@NeTpower.com>
> To: "quattro" <quattro@coimbra.ans.net>
> Subject: Air leak (88, audi 90)

> A while back my car (1988, audi 90 fwd, 5speed) suffered from surging idle 
> which
> eventually I traced to the idle stabilizer unit.  For the past couple of 
> months
> I am driving the car with electrical connection to this unit
> disconnected.  The most noticeable symptom was that with AC on
> the idle was uncomfortably low...
> 
> Anyways last weekend while changing  the oil, I decided to take the unit out
> and clean it hoping I would get rid of this problem cheaply.  I sprayed 
> hefty
> amount of gunk  in two orifices and let it sit for an hour or so.  While
> trying to install the unit, I managed to push on a vacuum tube which in turn 
> 
> broke a three way plastic piece (for a lack of better word).  which has 
> three
> vacuum connection (two ~1inch diam & 1 ~0.25 inch diam).  Needless
> to say the car would not start...  This morning I picked up the replacement
> part and with everything correctly (so he says!!) put back together I 
> managed to
> start the car only once.  I ran it at about 2K rpm for a minute or two. 
>  However
> the car would not hold idle and refused to start with or without electrical
> connection to the idle stablizer unit.  Periodically I would clean the spark
> plugs to make sure they were not flooded.
> 
> 
> 
> At this point  I have no problem replacing the stabilizer unit.  However
> I have a hard time believing that a "simple" spraying would do this
> much damage.  Was wondering if you guys have any suggestions....
> 
> 
> 
> Thanks,
> 
> David
> 

My car ('88 90Q) also will surge at idle, when the electrical connection to the idle 
stabliser valve (ISV) has *failed*.  But, it will run, with the AC off, with out the 
ISV, as you indicate.   Now your car wil not start.  

That tells me that you don't have everything back together again.  My guess is that 
you have an open vacuum hose that is leaning out the mixture to the point it will 
not start. (This is also supported by the 2,000 rpm idle speed - the fuel injection 
will *try* to richen the mixture to account for air leaks, if they are not to big).   
The ISV connection runs under the intake manifold to the intake plumbing behind the 
intake manifold.  You may have pulled a hose off there.  

Keep checking :).

--------------------------
Allan Morris
Phoenix, Arizona
allanm@primenet.com
-------1988--90Q----------