Purpose of Crank and Cam sensors?

[ShafferNY]

I'm just curious here.

If the crank and cam are directly linked by way of a timing chain, why are there two sensors?

I'm thinking the cam sensor is what effects injector timing, and the crank sensor is what effects ignition timing.

Correct?

 

[Joe W]

Alright, I'm gonna' take this one........I read somewhere that there is a signal wheel bolted to the crank that has slots which the crank sensor picks up for spark and injection.....However since the crank rotates twice for every 4 strokes (720 degrees of rotation) and the cams rotate only once the cam sensor lets the computer know whether it is the first 360 degrees or the second 360 degrees and this lets it fire the proper cylinder.....hope this helps, Joe W.

 

[ShafferNY]

That makes sense.