Engine and Emission Control System Description - Ignition Timing Control (Cont'd)

The ignition timing is controlled by the E.C.U. in order to maintain the best air-fuel ratio in response to every running condition of the engine. The ignition timing data is stored in the ROM located in the E.C.U., in the form of the map shown below. The E.C.U. detects information such as the injection pulse width and crank angle sensor signal which varies every moment. Then responding to this information, ignition signals are transmitted to the power transistor. e.g. N: 1,800 rpm, Tp: 1.50 msec A deg.B.T.D.C. In addition to this, 1) At starting 2) During warm-up 3) At idle 4) At acceleration the ignition timing is revised by the E.C.U. according to the other data stored in the ROM.