Detroit Diesel Electronic Controls ELECTRONIC PILOT INJECTION (EPI) Normal fuel injection has long ignition delays resulting in large quantities of fuel to be injected before the beginning of combustion. With large amounts of fuel at the beginning of combustion, there is a high rate of cylinder pressure rise, white smoke from unburned fuel and excessive combustion noise. DDEC controlled Electronic Pilot Injection (EPI) provides a small quantity of fuel injection in advance of the normal injection beginning the combustion process. This is followed by the main quantity of fuel injection to complete combustion.
EPI is a form of indirect injection reducing the ignition delay period thereby reducing the rate of pressure rise effectively reducing the unburned fuel and cylinder knock during startup. Significant reduction in fuel consumption, peak cylinder pressure, rate of pressure rise and emissions are all achieved with EPI. HALF ENGINE IDLE The half engine idle feature controlled by DDEC enables the engine to maintain higher cylinder temperature during idle to light load operating conditions. Half engine idle is activated depending on the percent of load, air intake temperature and engine coolant temperature. Half engine operation may occur up to 1900-rpm engine speed.
Half engine operation differs with the 12V4000 from the 16V4000 models on the 12V, only the master ECM fires the “A” bank cylinders; with the 16V, both ECM’s control (4) cylinders each for either bank randomly. Page 12