what exactly is a knock sensor??
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
it's basically a microphone...
It picks up vibrations in the engine, if the vibrations are outside of normal operating sounds it tells the PCM about it, and the PCM will pull timing amongst other things...
the Knock sensor exists to stop detonation as soon as it's detected
It picks up vibrations in the engine, if the vibrations are outside of normal operating sounds it tells the PCM about it, and the PCM will pull timing amongst other things...
the Knock sensor exists to stop detonation as soon as it's detected
As a device it is a piezoelectric crystal. It has 5 volt reference going to it. It eats up about 1/2 that voltage through it's own resistance. So it's about 2.5 volts hooked up.
When a knock occurs the voltage will change to above & below 2.5 volts. This is what the PCM sees as a knock, a varied voltage & amount of time voltage varies.
When a knock occurs the voltage will change to above & below 2.5 volts. This is what the PCM sees as a knock, a varied voltage & amount of time voltage varies.
