Importance

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Abstract

A momentary diagnostic for determining correct operation of a cam profile switching system of an internal combustion engine by calculation of changes in cylinder bank to bank air mass flow ratios: operating said engine in one condition of the cam profile switching system; providing for a first cylinder subset the inlet fuel flow and the corresponding oxygen content of the exhaust flow, and calculating the mass of air passing through the first cylinder subset in a defined time period; providing for a second cylinder subset the inlet fuel flow and the corresponding oxygen content of the exhaust flow; calculating the mass of air passing through the second cylinder subset in said defined time period; comparing the mass air flow the oxygen content for the first and second cylinder subsets to give a standard ratio; momentarily forcing the cam profile switching system of one of said cylinder subsets to an alternative condition; re-calculating providing the corresponding mass of air oxygen content passing through the first and second cylinder subsets; and comparing said recalculated air flows oxygen contents to give a revised ratio; and comparing said standard ratio and revised ratio.

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First Claim