9-3 (9440) L4-2.0L Turbo (2007)
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CDM performs an initial processing of the ionization signal from each ignition coil. CDM generates a common knock signal from the ionization
information of the four cylinders. This signal is used by ECM to evaluate engine knocks.
After the spark has been fired, ECM "listens" to the knock signal of each cylinder over a certain number of crankshaft degrees, known as "windows".
The ionization signal is band-pass filtered to filter out the part of the signal containing knock information.
Knock information is characterised by "ringings" which are oscillations in the ionization signal. To obtain the combustion signal, the ionization signal
