Computerized Engine Controls: XJS

The XJS has one Electronic Control Unit (ECU) to control the ignition system and another ECU to control the fuel system. The Electronic Fuel Injection (EFI) ECU is a digital ECU with an integral manifold pressure sensor, which governs the amount of fuel to be injected by controlling injector pulse width. Manifold pressure and speed signal provide the main control for the fuel injection. The ECU uses additional sensors to monitor engine temperature, inlet air temperature and throttle position to ensure optimum air/fuel mixture is computed for all engine operating conditions.

The microprocessor located within the digital ignition system ECU controls the timing of the low tension voltage by means of 2 ignition coils and 2 amplifier units, located on the front crossmember. The front coil supplies high tension voltage to the "B" bank (left cylinder head) and the rear coil supplies high tension voltage to the "A" bank (right cylinder head). The ECU controls the ignition timing according to the inputs received from sensors located on and around the engine. System is equipped with a Limp Home mode. The ECU will substitute a nominal value for missing inputs from the coolant temperature sensor, air temperature sensor, throttle potentiometer, oxygen sensor(s) and/or manifold pressure sensor.