1A-18 Engine Control System Operation ECM calculates the optimum target injection timing for the engine condition, adding the compensation by signals from sensors based on the basic target injection timing. At the time of start, the injection timing is determined by the starter signal, coolant temperature and engine speed (at the higher engine speed, the injection timing angle advances.) Crank angle feedback system is employed to calculate the actual injection timing and feed back the result at the target injection timing. 1. Basic target injection timing Determined based on the accelerator opening and engine speed. 2. Injection timing compensation a.
Intake air pressure compensation Basic target injection timing is compensated by the intake air pressure. When the atmospheric pressure is low on a altitude, for instance, the injection timing angle is advanced. b. Coolant temperature compensation Basic target injection timing is compensated based on the coolant temperature. When the coolant temperature is low, the injection timing angle is advanced. 3. Feedback control a.
Calculation of actual injection timing When relation between the compression TDC position and crank angle reference position signal is correct on the engine side and the relation between the injection waveform and cam angle signal is correct on the pump side, actual injection timing θ n can be calculated by calculating the phase difference θ i between the crank angle reference position signal and cam angle signal.
Accelerator Position Speed Sensor Crank Position Sensor Sensor Basic Target Injection Actual Injection Timing Timing Intake Air Pressure Sensor Angle Advances When Lower Compen- Coolant Temperature sation Sensor Angle Advances When Lower Target Injection Timing Compen- sation Compensation ROM Comparison with Target Injection Timing and Compensation Value Actual Injection Timing of Each Pump Calculation of Duty Ratio Timing Control Valve LNW21AMF001101-X