Internal combustion engine operation diagnosing method, involves determining idle air flow change as engine is operated in selected compression ratio operation states, and evaluating operation based on air flow change

摘要

The method involves determining a change in idle air flow of an internal combustion engine (110) by operating the engine in two selected compression ratio operating states. The operation of the engine is then evaluated based on the change in idle air flow obtained for the selected compression ratio operating states. An Independent claim is also included for a system for operating an internal combustion engine having multiple compression ratio operating states.