900 SE Convertible V6-2489cc 2.5L DOHC EFI (1997)
Knock Sensor: Description and Operation
The B258 engine has two knock sensors, one for each bank of cylinders. On the basis of information supplied by the camshaft position sensor, the
control module knows which cylinder is under compression when ignition occurs.
If knocking is detected, the ignition will be retarded in the relevant cylinder in steps of 3° until the knocking ceases. It will then be advanced in steps of
0.75° until knocking recurs or until the original timing is restored.
The engine has two identical knock sensors, one for the front and one for the rear bank of cylinders. Each knock sensor contains a piezoelectric element
which produces an electric current when subjected to pressure.
