DT466E fuel injection control components

The engine oil pump, which is bolted to the front cover around the crankshaft nose, provides lubricating oil for the engine and supplies the high pressure oil pump reservoir in the upper left part of the front cover.
The engine oil temperature sensor is screwed into the high pressure oil reservoir next to the high pressure pump. It tells the ECM the oil temperature and thereby its viscosity. This is probably one of the less important components, except in temperature extremes. Removing it confirms the presence of oil in the high pressure reservoir.

The High pressure oil pump, on the back side of the top left front cover, provides oil at up to 6000psi to actuate the fuel injectors.

The Injection Pressure Regulator (IPR) on the high pressure pump uses voltage from the Engine Control Module (ECM) to regulate the injection control pressure by opening a bypass valve in the pump. 12 volts can be temporarily applied to the regulator to close it completely to test the pump's maximum pressure. If it generates rated pressure this eliminates the pump as a no start or performance problem.

The ICP sensor, on the oil supply manifold, tells the ECM how much pressure the injection control pressure system is making moment by moment.

Injectors take the injection control pressure and magnify it 7X to provide fuel injection pressure. Therefore, if the injection control pressure is 3000 psi, the fuel will be injected at 21,000 psi. The injectors are unit injectors, meaning that the fuel is brought to injection pressure inside the injector itself, instead of being supplied at injection pressure from a pump via a manifold as in high pressure common rail injection, or by individual lines as in mechanical injection.

The Engine Control Module (ECM) is the engine’s brain, taking all the sensor inputs into account to determine when and for how long to inject fuel.

Injector Driver Module (IDM) has a transformer that supplies and distributes high voltage to open and close a valve in the injectors, letting high pressure oil inject fuel. In pre-2004 engines it is enclosed in the same housing as the ECM and this combination is also known as the CEC (Consolidated Engine Controller). 2004 and later engines have separate ECM and IDM units stacked on the left rear of the engine block.

The MAP (Manifold Absolute Pressure) sensor tells the ECM how much pressure is developed in the intake manifold so the proper amount of fuel is injected at a given engine load and RPM.

Also used to control and monitor the system is a Cam Position Sensor (CMP), a Throttle Position Sensor (TPS), Intake Air Temp sensor (IAT), Crank Position Sensor, (CKP, on EGR motors), and Exhaust Back Pressure sensor, (EBP, on EGR motors).

The fuel pump is a mechanical unit bolted to and driven by the high pressure pump. Steel fuel lines connect it to the fuel filter and on the pre-EGR engine, to the fuel/oil manifold. There is an electric pump on trucks with dual fuel tanks, but it only serves to equalize the fuel level between the tanks and does not feed the engine.

The standard fuel filter setup on pre-EGR engines is a single spin-on fuel filter and a small sediment bowl containing a particulate screen. Some trucks may be equipped with a fuel separator which could be found on either side of the engine.

EGR engines have a fuel conditioning unit with a cartridge type filter and a sediment bowl with a particulate screen on the bottom of the filter canister. A standard water in fuel sensor and optional fuel pressure sensor are in the sediment bowl and the filter housing, respectively.

The fuel pressure regulator is in the fuel canister on EGR engines. It is accessed and inspected by removing the top of the canister and removing the filter. It can be seen at the bottom of the canister, and has an Allen head. There is no return fuel to the tank(s) on the EGR engine, as return fuel recirculates back to the suction side of the system.

On earlier, pre-EGR engines the regulator is screwed into the rear end of the fuel/oil manifold. Return fuel flows through the regulator to the return line to the fuel tank(s).

Pages