Circuit/System Description

The engine control module (ECM) has the ability to learn injector timing performance. With the engine at operating temperature and in deceleration fuel cut-off mode, the ECM will pulse each injector individually and measure the changes in rotational speed of the crankshaft using the input from the crankshaft position sensor (CPS). The ECM will run this diagnostic at one fuel rail pressure operating point for each injector. The ECM stores the injector timing value.