[V8] sanity check, what, from a V8Q owner?

cobram at juno.com cobram at juno.com
Tue Mar 18 14:29:07 PDT 2008

I think the only difference would be whether the Audi is a V8Q or not. 
Because of the even number of cyls and the distributors firing at fixed
degrees, the ECU in this case does NOT need to know (unlike an I5) if you
are at TDC on  #1 or not to run.  It does effect the knock sensor  (which
default to 16 deg. BTDC) making for less than optimal performance, but
not related to starting at all.
The hall signal is used with other parameters to time injector firing to
reduce emissions, aside from this it's like a CIS system in that it
doesn't matter for normal operation.

Former lister Keith had a very good write up on it take from the Audi
literature, it's probably in the archives somewhere.  

Easy to prove, disconnect the hall sender @ the distributor on any V8Q
which doesn't have a preexisting problem and see for yourself.  

Developer: Someone who wants to build a house in the woods.
Ecologist: Someone who has already built his house in the woods.

Bastian Preindl <bastian at preindl.net> writes:

> we've have divorcing experiences concerning this... the one says no 
> problem, the other had a defect Hall sensor and no way to start it 
> up. 
> I'm also wondering, as I say one of the both has to be there: 
> ignition point or hall, in theory. But what if the ignition point
sensor is 
> already not the best any more (probably already causing an 
> intermittend error) which can still be corrected by the Hall sensor.
When the 
> Hall sensor brakes, everything is over.
> But exactly what you say covers several discussions on audiv8.com as 
> both behaviours have been experienced...
> Bastian

> > It cannot be the hall sensor, the V8Q defaults to a fixed value in 
> an out
> > of parameter or absence of a hall signal.  You can unplug the hall 
> sender
> > and the V8Q will run and start.

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