Electronically controlled injectors 2.7L (Discovery 3)

Six electronically controlled injectors (by the number of engine cylinders) are located along the vertical axis of the cylinders, between the four valves. ECM (engine control unit) divides the injectors into two banks of three cylinders each: cylinders 1 through 3 are assigned to bank A, and cylinders 4 through 6 are assigned to bank B. Injectors numbered 1 and 4 are located at the front of the engine. Although the injectors are numbered 1 through 6, the firing order of the cylinders, as determined by the ECM, (engine control unit), is determined based on the numbering 0-5.

Numbering of injectors and cylinders

Nozzle	Cylinder number
0	1
1	4
2	2
3	5
4	3
5	6

Fuel under high pressure is supplied to the injectors from the fuel rail and is sprayed by them into the combustion chambers in a finely dispersed form. ECM (engine control unit) controls each injector separately using the cylinder firing order, with the injector opening period controlled by PWM (pulse width modulation) -signals. ECM (engine control unit) supplies 12 V supply voltage to each injector and, based on programmed injection moment/volume maps and sensor signals, calculates the exact moments of the preliminary and main fuel injection phases for each cylinder. If the battery voltage drops to 9 - 6 V, the injector controllability deteriorates, which worsens environmental parameters and engine operation in idle mode, and also affects the engine speed range. Injector failure may be accompanied by the following symptoms:

• Misfires
• Idle speed unevenness
• Reduced engine power
• Deterioration of engine energy performance
• Difficult start
• Increased exhaust smoke

ECM (engine control unit) controls the electrical conductivity of the wires of each injector (checking them for short circuits and open circuits), each injector and transient current in eCm (engine control unit). If a defect is detected in the ECM (engine control unit) an error is logged for the injector being tested. For more information, see Fuel Charging and Controls (303-04C Fuel Charging and Controls - 2.7L Diesel)

(The original text can be found at LRMAN.RU)