The ecm needs to know as they sequential fire the injectors. It needs to know where number one cylinder is.

 

Okay, I understand, but where in degrees is the missing tooth located, is that No. 1 at TDC or elsewhere? also, why does the computer need to know where the CAM is, to determine that No. 1 is in the compression stroke? Where in degrees does the cam sensor trigger?

 

What engine are we talking about here? Ford use a 36 minus 1 reluctor wheel and the place missing a tooth represent cylinder number 1. One tooth equals 10 degrees of rotation, 360 degrees divided by 36 teeth. Don't forget these are 4 stroke engines and the cam sensor is needed to determine which stroke the cylinder is on, be it intake, compression, combustion or exhaust. The LS1 used a 24x reluctor wheel, then switched to a 58x one later on.

 

Makes sense. Thinkin' about a 4.6 FORD Mod motor. Is it a fair guess that the missing tooth is TDC on No. 1?

 

Makes sense. Thinkin' about a 4.6 FORD Mod motor. Is it a fair guess that the missing tooth is TDC on No. 1?

Yes! You could make it any cylinder depending how you align the sensor.

 

Typically the cam sensor will be telling the ECU when #1 is approaching TDC for injector firing purposes. Crank trigger controls spark. You can make them anything you want but anything except what's correct will mean a non running engine.