A pulse-width controlled current energizes the open

coil. Magnetic force moves the spool valve  open.

High-pressure oil flows past the  spool valve and

onto the top of the intensifier  piston. Oil pressure

overcomes the force of the intensifier piston spring

and the intensifier starts to move down. An increase

in fuel pressure under the plunger seats the fuel inlet

check ball, and fuel pressure starts to build on  the

needle.

The pulse-width controlled current  to the open

coil is shut off, but the spool  valve remains open.

High-pressure oil from high-pressure oil manifold

continues to flow past the spool valve. The intensifier

piston and plunger  continue to move and fuel

pressure increases in the barrel. When fuel pressure

rises above the VOP, the needle lifts off the seat and

injection begins.

End of Injection

When the ECM determines that the correct injector

on-time has been reached (the correct amount of fuel

has been delivered), the ECM sends a pulse-width

controlled current to the close coil of the injector. The

current energizes the close coil and magnetic force

closes the spool valve. High-pressure oil is stopped

against the spool valve.

The pulse-width controlled current to close the coil

is shut off, but the spool valve remains closed. Oil

above the intensifier piston flows past the spool valve

through the exhaust ports. The intensifier piston and

plunger return to their initial positions. Fuel pressure

decreases until the needle control spring forces the

needle back onto the seat.

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Systems Operation  Section

Fuel Supply System

g02729994

Illustration 26

Typical example of low-pressure fuel  system

(1) Cylinder head

(2) Electronic unit injector

(3) Fuel filter cap

(4) Fuel filter base

(5) Diagnostic coupling assembly and dust

cap

(6) Transfer pump outlet tube assembly

(7) Water drain valve

(8) Water In Fuel (WIF) sensor

(9) Engine Fuel Pressure (EFP) sensor

(10) Low-pressure fuel pump

(12) Fitting assembly with check valve

(13) Fuel priming pump

(14) Fuel strainer cap

(15) Low-pressure fuel rail

(11) Transfer pump inlet tube assembly

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KENR8772

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Systems Operation  Section

g02730792

Illustration 27

Typical example of the fuel supply  system flow

(A) Fuel strainer

(F) Fuel tank

(8) Water In Fuel (WIF) sensor

(B) Fuel standpipe (fuel entry high point)

(C) Fuel pressure regulator valve

(D) Fuel filter service drain to tank valve

(E) Diagnostic port

(2) Electronic unit injector

(4) Fuel filter base that includes  fuel filter

and water separator

(9) Engine Fuel Pressure (EFP) sensor

(10) Low-pressure fuel pump

(13) Fuel priming pump

(7) Water drain valve

(15) Low-pressure fuel rail

The low-pressure fuel pump draws fuel through the

fuel lines from the fuel tank. Fuel enters the fuel filter

header assembly and passes through the 150 micron

strainer.

Fuel flows through  the filter element and  the

standpipe. The filter element removes debris from

the fuel. The standpipe prevents fuel from draining

from the fuel rail during service.

Fuel flows from the strainer through the low-pressure

fuel pump to the fuel filter for further conditioning.

If water is in the fuel, the fuel  filter element repels

the water. The water is collected at the bottom of the

main filter element cavity in the fuel filter assembly.

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KENR8772

Systems Operation  Section

When the maximum amount of water is collected in

the element cavity, the Water In Fuel (WIF) sensor

sends a signal to the Engine Control Module (ECM).

A water drain valve  is located on the fuel  filter

assembly and can be opened to drain contaminants

(usually water) from the assembly.

A fuel pressure regulator  valve is built into the

fuel filter header assembly. The regulator valve is

calibrated to open at 455 ± 34 kPa  (66 ± 5 psi) to

regulate and relieve excessive fuel pressure. Excess

fuel is sent through a fuel return line back to the fuel

tank. Return fuel is not filtered.

Fuel continuously flows from  the top of the filter

element cavity, through a 0.2 mm air purge orifice

(filter center tube feature), and into the  return fuel

line. This aids in  removing trapped air from the

element cavity as a result of servicing.

When the fuel  filter is removed, an automatic

drain-to-tank valve is opened. Fuel present in the

filter housing then drains out and back to the tank to

provide improved cleanliness during servicing.

The Engine Fuel Pressure (EFP) sensor detects low

fuel pressure caused by a fuel  restriction or dirty

fuel filter. The EFP sensor  sends a signal to the

ECM when pressure is below programmed values for

various engine conditions.

Filtered fuel flows from the fuel filter header assembly

into the fuel rail. The fuel rail is an integral part of the

intake manifold. The fuel flows into six cylinder head

passages to each fuel injector.

When the fuel injectors are activated, fuel flows from

the fuel passages through the injector inlet ports and

inside the fuel injectors.

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KENR8772

37

Systems Operation  Section

i04031072

Air Inlet and Exhaust System

g02729092

Illustration 28

Typical example

(1) Inlet Air Heater Control (IAHC)

(2) Valve for the  NOx Reduction System

(NRS) (if equipped)

(4) Inlet manifold air pressure sensor

(8) Turbocharger

(9) Exhaust gas cooler (NRS) (if equipped)

(5) Charge Air Cooler (CAC)

(6) Exhaust back pressure sensor

(7) Air filter assembly

(3) Inlet air temperature sensor

Note: The white arrows show the flow of inlet air. The

black arrows show the flow of exhaust gases.

•  Turbocharger

•  Charge Air Cooler (CAC)

•  Intake throttle valve

The engine components of the air inlet and exhaust

system control the quality of air and the amount of

air that is available for combustion. The components

of the air inlet and exhaust system are the following

components:

•  NOx Reduction System (NRS) (if equipped)

•  Inlet manifold

•  Air cleaner

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KENR8772

Systems Operation  Section

•  Inlet Air Heater Control (IAHC)

•  Valves and valve system components

•  Piston and cylinder

•  Exhaust manifold

Air flows through the air filter assembly and enters

the turbocharger. The turbocharger compressor

increases the pressure, temperature, and density of

the intake air before the air enters  the Charge Air

Cooler (CAC). Cooled compressed air flows from the

CAC into the inlet manifold and duct of the control

valve for the exhaust gas valve.

If the control valve for the exhaust gas valve is open,

exhaust gas will pass through the NOx Reduction

System (NRS) and mix with the filtered  intake air.

This mixture flows through the inlet air heater and

into the inlet manifold.

If the control valve  for the exhaust gas valve is

closed, only filtered intake air will flow through the

inlet air heater and into the inlet manifold.

After combustion gases exit through the  exhaust

valves and ports, the  gas is forced through the

exhaust manifold to the NRS and turbocharger.

Some gas flows through the NRS system, which is

controlled by the exhaust gas valve. The remaining

gas flows to the turbocharger turbine.

The compressor wheel is connected to the turbine

wheel by a shaft. The  turbocharger compressor

wheel compresses the filtered air.

Exhaust gases exit the turbocharger and are released

from the exhaust system.

Charge Air Cooler (CAC)

The Charge Air Cooler (CAC) is  mounted on top

of the radiator. Air from the  turbocharger passes

through a network of heat exchanger tubes before

entering the engine intake system. Outside air flowing

over the heat exchanger tube fins cools the charge

air. Cooling the charge air increases the density and

improves the air to fuel ratio during combustion.

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KENR8772

39

Systems Operation  Section

NOx Reduction System (NRS) (If

equipped)

g02730874

Illustration 29

Typical example

(1) Exhaust gas cooler (NRS)

(2) Inlet manifold

(3) Metering tube

(5) Valve drive module

(6) Valve for the NOx  Reduction System

(NRS)

(8) Coolant supply tube

(4) Exhaust gas valve (NRS)

(7) Coolant return tube

The NOx Reduction System (NRS) reduces Nitrogen

Oxide (NOx) engine emissions. NOx forms during

a reaction between nitrogen and  oxygen at high

temperatures during combustion. Combustion starts

when fuel is injected into the compressed combustion

chamber.

Metered exhaust gas from the  exhaust manifold

flows into the exhaust gas cooler. Cooled exhaust

gas flows through the exhaust tube assembly to the

exhaust gas control valve.

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KENR8772

Systems Operation  Section

When a reduction in NOx is required, the exhaust

gas control valve opens and allows cooled exhaust

gas to enter. This exhaust gas is directed into  the

exhaust gas valve duct where the exhaust  gas is

mixed with filtered inlet air.

Turbocharger

Exhaust Gas Control Valve (If equipped)

The exhaust gas control valve consists of three major

components, a valve, an actuator  motor, and an

Integrated Circuit (IC).

The exhaust gas control valve  is installed in the

exhaust gas valve manifold on the top front of  the

engine.

The exhaust gas valve uses a DC motor to control

position of the valve assembly. The motor pushes

directly on the valve stem to open. The valve is shut

by a spring. The valve assembly  has two poppet

valves on a common shaft.

The Integrated Circuit (IC)  has three hall effect

position sensors to monitor valve movement.

g00302786

Illustration 30

Typical example of a cross section of a turbocharger

(1) Air intake

NOx Reduction System Closed  Loop

System (If equipped)

(2) Compressor housing

(3) Compressor wheel

(4) Bearing

(5) Oil inlet port

(6) Bearing

The ECM commands the exhaust gas control valve

position based on engine speed and load conditions.

The exhaust gas control valve provides feedback to

the ECM on current valve position.

(7) Turbine housing

(8) Turbine wheel

(9) Exhaust outlet

(10) Oil outlet port

(11) Exhaust inlet

The turbocharger is mounted on the outlet  of the

exhaust manifold. The exhaust gas from the exhaust

manifold enters the exhaust inlet (11) and passes

through the turbine housing (7) of the turbocharger.

Energy from the exhaust gas causes  the turbine

wheel (8) to rotate. The turbine wheel is connected

by a shaft to the compressor wheel (3).

As the turbine wheel rotates, the compressor wheel

is rotated. The rotation of the  compressor wheel

causes the intake air to be pressurized through the

compressor housing (2) of the turbocharger.

When the load on the engine increases, more fuel

is injected into the cylinders.  The combustion of

this additional fuel produces more exhaust gases.

The additional exhaust gases cause the turbine and

the compressor wheels of the turbocharger to turn

faster. As the compressor wheel turns faster, air is

compressed to a higher pressure and more  air is

forced into the cylinders. The increased flow of air

into the cylinders allows the fuel  to be burnt with

greater efficiency. This produces more power.

When engine load is light, the flow of exhaust gases

decreases which causes reduction in air volume and

boost pressure.

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41

Systems Operation  Section

A wastegate is installed on the turbine housing  of

the turbocharger. The wastegate is  a valve that

allows exhaust gas to bypass the turbine wh, eel of

the turbocharger. The operation of the wastegate is

dependent on the pressurized air (boost pressure)

from the turbocharger compressor.

The valve system components control the flow  of

inlet air into the cylinders during engine operation.

The valve system components also control the flow

of exhaust gases out of the cylinders during engine

operation.

The crankshaft gear drives the camshaft gear through

an idler gear. The camshaft (5) must be timed to the

crankshaft in order to get the correct relation between

the piston movement and the valve movement.

The shaft that connects the turbine to the compressor

wheel rotates in bearings (4) and (6). The bearings

require oil under pressure for lubrication and cooling.

The oil that flows to the lubricating oil inlet port (5)

passes through the center of the turbocharger which

retains the bearings. The oil exits the turbocharger

from the lubricating oil outlet port (10) and returns

to the oil pan.

The camshaft (5) has two camshaft lobes for each

cylinder. The lobes operate either  a pair of inlet

valves or a pair of exhaust valves. As the camshaft

turns, lobes on the camshaft  cause the lifter (4)

to move the pushrod  (3) up and down. Upward

movement of the pushrod (3) against the rocker arm

(2) results in a downward movement that acts on the

valve bridge (1). This action opens a pair of valves

(7) which compresses the valve springs (6). When

the camshaft has rotated to the peak of the lobe, the

valves are fully open.

Crankcase Breather

NOTICE

The crankcase breather gases are part of the engines

measured emissions output.  Any tampering with the

breather system  could invalidate  the engines  emis-

sions compliance.

When the camshaft (5) rotates further, the two valve

springs (6) under compression start to expand. The

valve stems are under tension of the springs. The

stems are pushed upward in order to maintain contact

with the valve bridge (1).  The continued rotation

of the camshaft (5) causes the rocker arm (2), the

pushrods (3) and the lifters (4) to move downward

until the lifter reaches the bottom of the  lobe. The

valves are now closed. The cycle is repeated for all

the valves on each cylinder.

A open crankcase breather system uses an engine

mounted oil separator to return oil to the crankcase

and vent crankcase pressure into the intake system.

The open crankcase ventilation system separates oil

from crankcase gases and returns oil to the oil pan.

A turbine in the breather housing assembly is driven

by engine oil pressure.

i04031012

Valve System Components

Lubrication System

g02440436

Illustration 31

Typical example

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KENR8772

Systems Operation  Section

g02729107

Illustration 32

Typical example

(1) Valve mechanism cover

(2) Rocker shaft assembly

(3) Reservoir for unit injector hydraulic pump

(4) Unfiltered oil gallery

(5) Housing (front)

(6) Oil pump

(7) Crankcase breather

(8) Suction pipe

(9) Turbocharger

(10) Oil cooler

(11) Oil filter

(12) Oil filter base

(13) Oil pressure regulator relief valve

(14) Regulator relief valve drain

(15) Oil pan

(17) Piston cooling jet

(18) Main filtered oil gallery

(19) Camshaft

(20) Cylinder block

(21) Vertical gallery

(22) Cylinder head

(16) Crankshaft

This document is printed from SPI². Not for RESALE