Transient A/F Characteristics for Cold Operation of a 1.6 Liter Engine with Sequential Fuel Injection

An investigation of transient A/F characteristics was conducted using a 1.6 liter engine equipped with a Sequential Electronic Fuel Injection (SEFI) system. The engine was tested on a dynamometer facility capable of providing environmental temperatures as low as 10°F. A test procedure was developed to determine the effects of steady state A/F, engine speed, size of throttle ramp, injection timing, and hardware changes, on the transient A/F characteristics while the engine warmed up. It was found that, under cold operating conditions, the A/F excursions for the SEFI system were similar to those previously measured for a Central Fuel Injection (CFI) system on the same engine. It was also found that the sensitivity of the A/F excursions to variations in the test parameters, while quite dramatic at reduced temperatures, decreased as the engine warmed up.