so slow...

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <s45dda7c.098@wppost.depaul.edu> Alex Kowalski (audial@aol.com) (Law Guest Account) writes:

> One other thing,
> 
> It was my understanding that on a car equipped with an
> electronically-controlled, crank-trigger ignition system the computer has
> the capability to compensate for some rotation of the distributor relative
> to the crankshaft and keep the timing in line.

The distributor has one and only one role to play in these situations.

The crankshaft (specifically, the periphery of the flywheel) is by far and away 
the best place to put timing sensors.  But there's a problem - the crankshaft 
of a four-stroke engine rotates _twice_ for every ignition stroke.
 
The Hall sensor on the distributor has only one function - to tell the ECU 
whether 'this' rotation is an ignition stroke (Hall sensor ticks) or an 
induction stroke (Hall sensor _doesn't_ tick).
 
In fact, it seems that Audi ECUs only look at the distributor (Hall sensor) 
during the first few revolutions of the engine during starting.  Subsequently, 
they keep track of the crankshaft position pretty carefully and the Hall sensor 
is not used.

-- 
 Phil Payne
 Committee Member, UK Audi [ur-]quattro Owners Club