Interesting ur-quattro problem

[quk@sievers.com (Phil Payne)]

In message <2.2.32.19970617112429.0314af4c@wagner.radstone.co.uk> Steve Evans writes:

> >His engine cut out on the way home, displaying the usual symptoms (only he 
> >didn't know this) of a broken inlet manifold chassis bonding wire.

> Exactly the same happened to me on Saturday (14th). I think this had something
> to do with the fact that I had just replaced the throttle switch assembly. The
> result - loads more torque at higher rpm leading to more engine movement - and
> a broken inlet manifold wire.

Yes.  It's an odd piece of circuitry - the engine block is grounded to chassis 
in at least three places - front of camshaft cover to above right headlight, 
rear of camshaft cover to ignition coil mounting, and alternator to chassis.
 
(Make that four - the transmission is also strapped.)

Those three wires (attached to the inlet manifold) go into the ECU wiring 
harness and metamorphose into around thirteen grounding wires for the ECU and 
some of its bits and pieces.  It seems that some of the ECU's sensors are so 
marginal that the voltage drops in chassis bonds are significant.

As an aside - I've just returned from a mercy mission with the microfiche 
reader to Roger Galvin's.  He has a nice 1984 Alpine White ur-quattro up on 
blocks, with the rear suspension and transmission spread all over the floor.  
It's now so long since he dismantled it, that he can't remember how it goes 
back together.  All went well (we mounted the rear differential and raised it 
to the car) until he started preparing the struts for re-fitting.  The powder 
coating has contaminated the threads at the base of the strut, and remounting 
the ball joint proved difficult.  He sheared one of the bolts off just as I was 
getting into the car to come home.
 
The _language_ was unbelievable!

All of this effort is to prepare the car for "concourse" at Goodwood.

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