Sniff sniff, its dead

[quk@sievers.com (Phil Payne)]

In message <Pine.SUN.3.91.970329170752.23428A-100000@marjoram.compnews.co.uk> Mike writes:

> After a lot of fault finding, its been traced back to the fuel distributer.
> Not quite sure what the problem is, but it is receiving fuel from the 
> pump etc, but the injectors are delivering didly squat to the engine.
> It starts now and again, runs for about 3-4 seconds, then cuts out again.
> You then have to turn it over lots and lots before it will fire again.

> Anyway the spanners are coming out tonight/tomorrow, but if anyone has 
> any ideas of something specific to look at, please let me know.

> My "fuel injection" friend, claims he has a very good idea of whats wrong 
> (something about a lever from the airbox into the bottom of the 
> distribution block) that has most likley seezed up.

I'd look at the warm-up regulator before the air mass sensor. Have you got the 
Bentley/Probst book on fuel injection?
 
Basically the fuel distributor does a balancing act - upward pressure on 
the plunger from the mass sensor (the "lever from the airbox") is 
balanced by downward pressure ("control pressure") from the warm-up regulator. 
If the warm-up regulator fails, it can result in "system pressure" being 
applied to the top of the plunger.  On my car, this kills the engine.
 
(System pressure is something over 6 bar - control pressure is around 3.4 bar 
on a warm engine and a lot less - as little as 2 bar - on a cold engine.)
 
The air mass sensor is easy to check - loosen (but do _NOT_ remove) the two 
10mm nuts either side of the mass sensor's plenum chamber (the globe-like 
thing).  Pull the hoses - one breather, one thin vacuum control to the membrane 
valve, and the main air hose down to the turbo.  Reach down below the nuts you 
loosened and swing out the L-shaped ends of the bolts.  Pull.
 
The plate inside should swing up and down freely without contacting the edges.  
If it does, the problem is most likely _NOT_ here. 

--
 Phil Payne
 phil@sievers.com
 Committee Member, UK Audi [ur-]quattro Owners Club