Nonlinear dynamic transform for correction of crankshaft acceleration having torsional oscillations

Engine apparatus for detecting misfires comprising:

• a crankshaft with a first crankshaft section being damped with respect to torsional oscillations created during engine rotation;
• a crankshaft position sensor generating position signals at predetermined rotational positions of said crankshaft, said crankshaft position sensor being juxtaposed with a second crankshaft section where torsional oscillations have a greater magnitude than at said first crankshaft section;
• a timer coupled to said crankshaft position sensor measuring rotation intervals corresponding to individual cylinder events during engine rotation;
• a processor coupled to said timer generating rotation quantities corrected for periodic position irregularities in said measured rotation intervals;
• a transformer coupled to said processor estimating said corrected rotation quantities occurring at said first crankshaft section;
• and
• a misfire detector coupled to said transformer for detecting misfires of said individual cylinder events in response to said estimated corrected rotation quantities.