Design and function General information EDC (Electronic Diesel Control) is a system in which the amount of fuel injected is controlled electronically, as distinct from the systems where the injected fuel volume is mechanically controlled. Difference between mechanical and electronic regulator In an injection pump with a centrifugal regulator, the in- jection volume is controlled mechanically. The centrifu- gal regulator is influenced by accelerator position, and compares it with the injector pump speed. The amount of fuel injected is increased or reduced, to make the in- jection pump turn at the speed corresponding to the ac- celerator position.
The main components of an EDC system are a micro- processor based control unit, and electromagnetic ac- tuator and a number of sensors which continually pro- vide the control unit with information. The EDC system The injection pump on the TWD740VE and TWD1231VE engines has an electromagnetic actuator. The actuator contains a solenoid which acts on the in- jection pump control rod, and thus influences the amount of fuel injected. In the EDC system, the centrifugal regulator in the in- jection pump is replaced by an electromagnetic actua- tor. The actuator is controlled by the control unit, which takes its information from a number of sensors located on the engine and controls, in its turn.
The EDC system has a built-in smoke limiting function. The system measures charge air pressure and mani- fold temperature, and thus calculates the amount of air available. The amount of air available determines the maximum permissible amount of fuel injected, in its turn. Injection pumps with a centrifugal regulator are equipped with a smoke limiter, in the form of a pres- sure-dependent full load stop. Engines with the EDC system do not have a mechani- cal smoke limiter. The corresponding function is inte- grated in the EDC system instead.
In order to achieve the minimum amount of emissions, the system measures the coolant temperature and uses this to determine the amount of preheating and post heating in the engine (please refer to the “Compo- nent description“ chapter). Curves, Preheating and Post Heating, and correct fuel volume. The system also de- cides the maximum amount of fuel which can be inject- ed at each engine speed. 40 13 Code Meaning Reason Reaction Action System assumes that engine tempera- Check cables and sensor connector. 3.3 Coolant temperature sensor System receives unreasonable values ture is 10°C. Can give increased Check sensor. Erase fault code.
from coolant temperature sensor exhaust smoke on starting. NOTE! Alarm for high coolant temperature does not function. Check cables and button connections. Button has been depressed > 2 minutes – 3.6 DIAGNOSIS” button Check button. Check cables and connections up to (EDC control panel) control panel. Erase fault code. 4.6 Starter motor relay Short circuit or open circuit in – Check cables and connections to starter relay in distri- cables / starter relay. bution box. Check starter relay. Erase fault code. – Check cables and connections to main relay in 5.1 Main relay Short circuit or open circuit in distribution box. Check main relay.Erase fault code. cables / main relay.
Check cables and connections to pre-heating relay in Short circuit or open circuit in – 5.4 Pre-heating relay distribution box. Check main relay. cables / pre-heating relay. Erase fault code. If the pressure is too high, the system Check the air filter. Check the pressure pipe from the will reduce the amount of fuel injected inlet pipe to the control unit. Check the Waste gate System receives too high or too low 5.6 Charge air pressure until the pressure is normalised (turbo valve.Erase fault code. value for charge air pressure. protection). 6.1 Fuel temperature Mass compensation ceases - engine Reduce fuel temperature. Erase fault code. Check Fuel temperature is too high. power is reduced.
the installation. 6.2 Charge air temperature Charge air temperature is too high. Check the intercoolers and the engine bay If the air temperature is too high, the temperature. Erase fault code. Check the installa- system will reduce the amount of fuel tion if the engine bay temperature is too high. injected until the temperature is normali- sed (engine protection.) 6.3 Engine temperature Engine temperature is too high. If the engine temperature is too high, the Check sensor cables. Erase fault code. Start the system will reduce the amount of fuel engine. injected until the temperature is normali- sed (engine protection.)