Ignition Timing

On Discovery Series I, ignition timing is controlled by Land Rover's Generic Engine Management System (GEMS) through the Engine Control Module (ECM) and is not adjustable. ECM, using Knock Sensor (KS), Camshaft Position (CMP) sensor and Crankshaft Position (CKP) sensor signals, can adjust each cylinder according to individual needs. Based on engine speed and load an optimum ignition timing can be set for each cylinder. As a result, there can be 8 different settings simultaneously. Always refer to SERVICE INFORMATION underhood label in engine compartment. If underhood label and lemon-25® manual specifications differ, always use underhood label specifications.

On Discovery Series II and Range Rover, ignition timing is controlled by Bosch Motronic M5.2.1 engine management system through the ECM and is not adjustable. ECM calculates ignition timing using input signals from the Crankshaft Position (CKP) sensor, Knock Sensor (KS), Mass Airflow (MAF) sensor, Throttle Position (TP) sensor (idle only) and Engine Coolant Temperature (ECT) sensor. ECM calculates dwell timing from battery voltage and engine speed. Individual cylinder spark timing is calculated based on engine speed, load and coolant temperature, knock control, automatic gearbox shift control and idle speed control.