Emission Optimized - Ignition Key Off

"Emission Optimized Ignition Key Off" is a programmed feature of the MS 54 ECM. After the ECM detects KL 15 is switched "off", the ignition stays active (ECM Relay/voltage supply) for two more individual coil firings. This means that just two cylinders are fired - not two revolutions.

This feature allows residual fuel injected into the cylinders, as the ignition key is switched off, to be combusted as the engine runs down.

When KL15  is switched "off" the ECM operating voltage is removed. The ECM will maintain a ground to the Engine Control Module Relay for a few seconds to maintain ignition coil activation.