Was reading this old thread with an excellent description of how engines detect knock. However, in doing some research on knock detection, I came across a video that explains a new type of knock detection being used by many manufacturers that is faster and much more effective than the older system of placing a couple sensors in the block. I didn't know this existed.Q:How is knock detected?
Since detonation results in noise (the rattling or pinging sound of the two colliding flame fronts), it can easily be detected through the use of microphones attached to the engine in key locations. On both the L36 and L67 3800 engines, there are two microphones. Each one is located immediately beneath a cylinder bank and are mounted in the block of the engine directly into the cylinder water jacket. As the sound of detonation occurs, the noise is ‘heard’ by the microphones and the signal is carried to the PCM where it is analyzed. The PCM determines whether or not the signal provided by the microphones is knock or just normal engine noise. Knock is detected by the frequency of the signal. The severity of the knock is determined by the voltage level of the signal. Another way to say it is the voltage level of the signal will determine the level of KR. The PCM is tuned to responded ONLY to those signal frequencies that it has been programmed to recognize as knock. Anything else is engine noise.
While there is one knock sensor per bank with the signal from the knock sensor and the signal from the crankshaft position sensor the engine controller can know which cylinder is generating the knock and deal with it on a per cylinder basis and even on a per power stroke basis but adjusting the fuel injector pulse width and adjusting the spark timing.Let's try this again:
I'm wondering if this new system might be a good thing, and if it might be in the works for future MOPAR engines?