I have a quick question, I have been reading all of these posts about this AI, and i am curious, what exactly is knock, also how do you monitor it, is it something that is built into the cars ecu, and also does a pfc monitor it automatically, and how accurate are the readings taken from it. THanks

 

Engine Knock. Generally what people are referring to though is actually pre-ignition, due to the high cylinder temperatures experienced in rotary engines and high boost. On a piston engine, knock or pre-ignition can both lead to engine damage if severe enough, blown pistons, bent rods, etc.

On a rotary engine, even minimal amounts of pre-ignition (or detonation) can and will destroy apex seals. Piston rings are much more durable due to the displaced pressure around the circumference of the ring, as opposed to the straight leading edge of an apex seal.

Stock ECU's monitor knock (with a knock sensor), and some adjust timing (retard it) to solve the issue. Many aftermarket EMS's also monitor it, and some even can retard timing based on it. I'm not really familiar with the PFC, but I'm pretty sure it does have the capability to monitor knock.

Other options are aftermarket "piggy back" style knock monitor devices, like the J & S Safeguard, which (on a rotary) intercepts the leading spark ignition signal, and upon sensing knock, retards IGL up to 10 or 20 degrees.

From what I've seen, knock readings from aftermarket EMS's seem to be pretty accurate with findings from J&S units.