Fuel Injection Quantity Control Description

Fuel Injection Quantity Control Description

This control determines the fuel injection quantity by adding coolant temperature, fuel temperature, intake air temperature, and boost pressure corrections to the basic injection quantity is calculated by the engine control module (ECM), based on the engine operating conditions and driving conditions.

Normal Running (Basic Injection Quantity) Control
During normal running, optimum fuel injection quantity is controlled according to the engine speed and accelerator pedal pressing amount. Combined with high pressure injection of atomized fuel, this control improves exhaust gas and ensures proper fuel consumption. Compared with conventional mechanical governors, an electronic control system provides higher degree of freedom of fuel injection quantity control, thereby presenting high accelerator response (acceleration feeling and pressing feeling).

Maximum Fuel Injection Quantity Control
The maximum injection quantity is calculated by adding the boost pressure correction, intake air temperature correction, barometric pressure correction and cold operation maximum injection quantity correction to the basic maximum injection quantity that is determined by the engine speed.

Starting Injection Quantity Control
At the engine starting (after the key switch is turned to the START position to start the engine, up to return of key switch to the ON position), optimum fuel injection quantity is controlled based on the information on the starter switch, engine speed, and coolant temperature. At low temperature, the fuel injection quantity increases. When the engine started completely, this boosted quantity mode at the starting is cancelled and normal running mode is restored.

Idle Speed Variation Stabilize Control
1. Idle Speed Control
A control is made so as to achieve stable idling speed at all time regardless of engine secular changes or engine condition variations. The engine control module (ECM) sets target idling speed and controls the fuel injection quantity according to the engine conditions (actual engine speed, coolant temperature, engine load ON/OFF signals of air conditioner) to follow actual engine speed to the target idling speed so as to ensure stable idling speed.

2. Idle Vibration Control
A control is made so as to reduce the engine vibration caused by torque variations between cylinders due to variations in fuel injection quantity of each cylinder or injector performance. The engine control module (ECM) corrects the injection quantity between cylinders based on the revolution signals from the crankshaft position (CKP) sensor. Normal range of correction quantity between cylinders is within +/- 5 cu.mm.