I'm so close to selling my caprice, but i'd hate too, i just love the car, when it doesn't have these days.
So, my caprice has obtained a new problem. It knocks ONCE when i start the car, and never does it again.
It only does it with the official PCM, and not my home-made "intelligent" PCM.
What can be causing this? The knock sensors and module are within spec.
(the only reason I'd want to use the official PCM, is incase mine breaks, i can have a fully working backup. my PCM has given me that "edge" i wanted, while the official PCM still has problems).
I even got a new PCM that is official to the car, same problem. My PCM is the only one that won't knock when I start the car.