90 Quattro 20V L5-2309cc 2.3L DOHC (7A) (1990)
Ignition Hall Effect Sensor: Description and Operation
MPI Start-Up Reference Signals
The hall sensor, located in the ignition distributor, generates a square wave signal which the ECU monitors. This signal, along with the crankshaft
reference sensor signal and engine speed sensor signal, is used to identify TDC of the firing stroke for #1 cylinder. This is necessary to calculate the
ignition timing, and fuel injection timing for the engine to start.