Locating #1 TDC with the OEM position sensor

[Begle1]

How does the OEM position sensor indicate #1 TDC? Is that where the missing tooth is or does it count a certain number of pulses from the missing tooth? Is it the same through the years or is every generation different?

 

[AsTroSS]

Cam gear is with hole for timing pin

 

[Begle1]

I mean, "how does the ECM know when the engine is at #1 TDC?"

It's my understanding that 24 valves all have a crank position sensor and a cam position sensor, both of which have a reference point (missing tooth) for the sake of timing control.

Where is the missing tooth located? Is the first pulse after the missing tooth right at #1 TDC (or some other arbitrary stroke position) or does the ECM count a number of pulses after the missing tooth or does some other digital magic happen?

It's my understanding that all 12 valves except the early non-intercooled models have just a crank position sensor to use as a tach signal. Do the 12 valve position sensors have any reference point (missing tooth) at all since it wouldn't be used for timing control?

 

[paulb]

Not all 24V's have crank sensors. I don't remember for sure what year it was dropped, but I do know my 02 does not have one.

Paul

 

[01PPUMP]

98-early 2000 have crank & cam sensors, late 2000-2002 only have cam sensor.

 

[Tate]

12v (atleast the 94-98 ones) have two notches in the damper. It doesn`t care where TDC is, it just wants to know if the engine is turning and how fast.