Ecd System (W/ Urea Scr System) System Description

Diesel Particulate Filter System comprehensively regulates engine control (consists of a catalytic system and a fuel injection system) that purifies particulate matter (PM) by diesel engines. The catalytic system purifies hydrocarbons (HC) and carbon monoxides (CO), and reduces PM with a catalytic converter with the Diesel Particulate Filter (DPF). The fuel injection system adds fuel into the exhaust port using the exhaust fuel addition injector to produce and maintain a proper catalyst temperature for PM forced regeneration.

DPF components:

Diagnostics Trouble Codes (DTCs) table for DPF:

HINT:

This table indicates typical DTC combinations for each malfunction occurrence.

Diagnostics trouble code description for DPF:

Urea SCR System:

1. A Urea SCR system is used to purify NOx in the exhaust gas. The urea SCR system injects urea solution into the exhaust gas to generate ammonia. The generated ammonia produces a chemical reaction with the NOx in the exhaust gas on the SCR catalyst, breaking it down into nitrogen and water, thereby purifying the exhaust gas.
   

2. The Urea SCR system is composed of a Urea pump control ECU, urea tank subassembly, urea injector set, urea pump, No. 4 exhaust gas temperature sensor and nitrogen oxides sensor.
   

3. In the Urea SCR system, the Urea pump control ECU controls the urea injector set and urea pump based on various signals.
   

Urea Pump:

1. The urea pump has the following functions:
   
   

   Function	Outline
   Pump Function	While performing feedback control according to the pressure sensor inside the urea pump, the pump raises the pressure to approximately 500 kPa, sending urea solution to the urea injector set.
   Heating Function	The heater inside the urea pump is operated to thaw the urea solution so that exhaust gas can be purified even when the ambient temperature is low and the urea solution freezes. The heater turns on and off according to the urea solution temperature sensor inside the urea pump.
   Filter Function	Foreign matter that enters the urea tank sub-assembly is collected by the filter inside the urea pump, preventing foreign matter from getting jammed in the urea pump and urea injector set.
   Level Gauge Function	The fluid level position is detected by the float sensor inside the urea pump in order to detect the remaining quantity of urea solution inside the urea tank sub-assembly.

Common rail system:
The common rail system uses high-pressure fuel for improved fuel economy. This system also provides robust engine power while suppressing engine vibration and noise.
This system stores fuel in the common rail, which has been pressurized and supplied by the fuel supply pump assembly. By storing fuel at high-pressure, the common rail system can provide fuel at stable fuel injection pressures, regardless of engine speed or engine load.
The ECM provides an electric current to the solenoid valve in each injector assembly to regulate the fuel injection timing and volume. The ECM also monitors the internal fuel pressure of the common rail using the fuel pressure sensor. The ECM causes the fuel supply pump assembly to supply the fuel necessary to obtain the target fuel pressure.
In addition, this system uses a solenoid valve inside each injector assembly to open and close the fuel passages. Therefore, both fuel injection time and fuel injection volume can be precisely regulated by the ECM.
The common rail system allows a two stage fuel injection process. In order to soften combustion shock, this system performs "pilot-injection" prior to the main fuel injection. This helps to reduce engine vibration and noise.

*1	Common Rail Assembly	*2	Fuel Pressure Sensor
*3	Pressure Discharge Valve	*4	ECM
*5	Crankshaft Position Sensor	*6	Camshaft Position Sensor
*7	Injector Assembly	*8	Pre-stroke Control Valve
*9	Fuel Supply Pump Assembly	*10	Exhaust Fuel Addition Injector Assembly
*11	Pressurised Fuel Filter	*12	Fuel Filter Assembly
*13	Fuel Tank Assembly	-	-
	Fuel (High Pressure)		Fuel (Suction)
	Fuel (Feed Pressure)		Fuel (Return)

HINT:

If there is a problem with a fuel return pipe, as bleeding air from the fuel system may not be able to be performed properly in certain instances, such as after replacing a fuel injector, etc., the engine startability may deteriorate.

Common rail system components:

Diagnostic trouble code (DTC) table for the common rail system:

HINT:

This table indicates typical DTC combinations for each malfunction occurrence.

Diagnostic trouble code description for the common rail system:

When the cam rotates the roller is pushed up, and in turn the plunger is pushed upward as well. When the plunger is not pushed up by the cam, it is pushed back down by the spring.

The ECM controls the timing of the pre-stroke control valve opening to regulate the fuel quantity. Consequently, the fuel pressure in the common rail is controlled to the target injection pressure.

The longer the pre-stroke control valve remains open, the quantity of pressure-fed strokes will decrease, as well as the fuel discharge quantity.

Pumping will start when the fuel pressure has become higher than the common rail pressure.

The less time the pre-stroke control valve remains open, the quantity of pressure-fed strokes will increase, as well as the fuel discharge quantity.

Pumping will start when the fuel pressure has become higher than the common rail pressure.