You forgot the part how the cam retard affects timing.
Like if the cam retard is out -10 degrees and the PCM commands 10 degrees of advance. You end up with no advance in timing.

 

Not as I understand it. The only thing that actually changes with CMPRET is the relative position of the rotor and the terminals inside the disty cap. The spark event occurs at the appropriate time regardless of the CMPRET value. It is just a matter of which spark plug that energy gets distributed to. This is where the "misfire" detection occurs. The plug that was expected to fire didn't and a different one did, or maybe a bit of both.


Of course, I may have this wrong, but I don't think so.

 

I don't think so. That would be basing the timing on cam sensor signal, not the crank sensor. If that was the case, turing the distributor body would affect timing and the vehicle wouldn't run with the cam sensor disconnected. Please re-read what the Captain wrote.

 

The camshaft position sensor creates a magnetic field. As the windows on the reluctor wheel pass the sensor, the magnetic field changes. The sensor converts those changes into pulses. The PCM can then compare crank & cam speeds to detect slight differences in speed between them, those differences represent a misfire. The PCM determines which cylinder misfired, and sets the appropriate DTC in memory. Keep in mind that not all manufacturers use their camshaft position sensor in the same way. On some vehicles, it does affect ignition timing, and it can cause a no-start condition... but not on the 1996 & newer 4.3's.

Burned, I do recall that conversation, and in theory it is correct, but in reality, due to the speed of the spark, it actually has a negligible affect on ignition timing. Sorry if I exagerated or misled.... or was totally wrong