1998 K2500 7.4L fuel pressure regulator replacement

[Schurkey]

I had planned to replace the cam position sensor since it controls the injector firing

My '97 service manual says the only thing the cam position sensor is used for, is misfire identification. (The computer uses the cam position sensor to determine WHICH cylinder is misfiring) Far as I know, ignition and fuel timing is handled by the crank sensor.

 

[Tom Nassar]

Schurkey--how would a camshaft position sensor be able to identify the misfire if it's not part of the firing? In other words, if the CKP sensor controlled the firing of the injectors, why couldn't the CKP sensor detect the misfiring as well?

 

[Schurkey]

Far as I know--and I could be wrong--all the "timing" of the injectors and spark is handled by the crank sensor input to the ECM.

The cam sensor in the distributor has input to the ECM that tells the ECM WHICH cylinder is firing, but that input doesn't change the timing. It's just an identification.

Without the cam sensor, the misfire would be determined to exist, but without being able to pin it to a specific cylinder.