S6 4RiNGS

it does for the car? and i ws told this can cause an irradic starting issue too.

kday

First a disclaimer: this is all just off the top of my head. I don't know for a fact that it works this way.

Assuming the engine speed sensor triggers once per flywheel revolution, the computer probably uses this to correlate camshaft position sensor pulses to crankshaft position. I.e the CPS triggers every small fraction of a camshaft revolution, and the other sensor triggers every 1 crank revolution. With both sensors the ECU can figure out exactly what the phase of the engine with relatively high resolution. This would explain starting troubles, because without the crank pulse the ECU doesn't know where the pistons and valves are. But once the engine is running the crank sensor isn't needed, because the ECU can just count cam sensor pulses.

If the above is correct there is probably some intentional assymmetry in the sensor wheel on the camshaft so the ECU can figure out which stroke corresponds with the crank pulse. I guess an odd number of teeth would be sufficient.

Now I'm curious... I wonder what the Bentley has to say about this.

GT500R

they are right next to each other on the D/S of the engine block. The one in front is the Crank Pos. Sensor and the other one is the Engine Speed Sensor. The Crank Pos Sensor reads one metal stud on the back of the flywheel that comes around once per rotation, telling the ECU where the crank is in relation to the Cam Pos Sensor. The Engine Speed Sensor just reads off the starter ring teeth and gives your RPM signal.