Adjustment of crank angle tolerance
Calculations are made using the stored data to generate an adaptive misfire 'signal'. Errors in the crank angle time data (for example, due to manufacturing tolerances) are calculated for each cylinder individually at pre-determined engine speed breakpoints. Compensating for these errors reduces the variation in amplitude of the misfire signal.
The data is gathered during normal combustion, requiring strict entry conditions to ensure robust adaptions. Adaption values are rolled in to a temporary calculation for the current speed breakpoint.