[urq] WX ECU Question

[Buchholz, Steven]

Yes.  In fact the signal from the Hall Sensor on the distributor actually
gates the reference pin signal so that only every other TDC is registered by
the ECU.  If the cam timing shifts or the Hall Sender signal is changed in
any other way so that the reference signal falls outside the window the
engine will not run ... even if it was running before.

The MC is very similar in this regard ... I am not as intimate with the ECU
circuitry to know whether or not there is an actual logic gate outside the
ECU as is true for the MAC-02, but the MC will also stop running if the
reference signal goes away.  Since the engine has an odd number of cylinders
it is a safety feature.

The only Audi engine I'm familiar with that only depends upon the reference
pin matching the dizzy at startup is the V8 engines similar to the PT.  

Steve B
San Jose, Kaleefohnia (USA)
> 
> Does the ECU check if the ignition timing reference pin falls inside the
hall sender
> window on a WX engine? Or, is it just used on start up to synchronize the
head
> with the crank? After startup you can unplug the hall sender and the
engine
> keeps running which makes me believe the reference window is not checked.
> I know this is the case for the MC engines where the ECU will throw a
code.