Can anyone explain why engines have both a crankshaft position sensor AND a camshaft position sensor? Why do we need both?

Thanks!

 

They both send signals to the ECM reporting that the cam and crank are in proper timing. The crank goes around twice to the cam one revolution. Therefore when the crank is number 1 up (TDC or top dead center), the ECM needs to know ignition or exhaust on the cam position.

James

 

Thanks, James. That makes sense. I figured since the crank turns the camshaft, they're never going to get out of sync. But, you're right; if the #1 piston is all the way up, what part of the cycle is it? Thanks again.

Tom G.

 

either exhaust or compression, depending on where the cam is

 

On GM anyway, it doesn't take much between the two sensors being off, to throw a code. A badly worn timing chain/and/or gear could do it as well.

 

Feedback for the variable cam timing?

 

I am not up on the latest technology, but is variable timing mechanical? I just figured electronic. Now you have me curious how they do it mechanical.

James

 

Cam timing 101.
This guys voice could put an insomniac into a deep sleep.
Variable CAM Timing - YouTube
There are others to view if you search.

I am not aware that we have variable cam timing though.

 

So how did all those old cars ever run so well in their day without all this BS technology we now have today

 

Makes you wonder, doesn't it?

180, thanks for the video, but I fell asleep. He sounds like a computer voice.

 

They did run well, they just used more gas and emitted more pollutants. Remember all the great smells at the Woodward Dream Cruise?

James