Page 458 of 2053

1F2 -- 40 M161 ENGINE CONTROLS
D AEW OO M Y_2000
FUEL SYSTEM
The function of the fuel metering system is to deliver the correct amount of fuel to the engine under all operating condi-
tions. The fuel is delivered to the engine by the individual fuel injectors mounted into the intake manifold near each
cylinder.
The main fuel control sensors are the Mass Air Flow (MAF) sensor and the oxygen (O2) sensors.
The MAF sensor monitors the mass flow of the air being drawn into the engine. An electrically heated element is
mounted in the intake air stream, where it is cooled by the flow of incoming air. Engine Control Module (ECM) modu-
lates the flow of heating current to maintain the temperature differential between the heated film and the intake air at a
constant level. The amount of heating current required to maintain the temperature thus provides an index for the
mass air flow. This concept automatically compensates for variations in air density, as this is one of the factors that
determines the amount of warmth that the surrounding air absorbs from the heated element. MAF sensor is located
between the air filter and the throttle valve.
Under high fuel demands, the MAF sensor reads a high mass flow condition, such as wide open throttle. The ECM
uses this information to enrich the mixture, thus increasing the fuel injector on-- time, to provide the correct amount of
fuel. When decelerating, the mass flow decreases. This mass flow change is sensed by the MAF sensor and read by
the ECM, which then decreases the fuel injector on-- time due to the low fuel demand conditions.
The O2 sensors are located in the exhaust pipe before catalytic converter. The O2 sensors indicate to the ECM the
amount of oxygen in the exhaust gas, and the ECM changes the air/fuel ratio to the engine by controlling the fuel
injectors. The best air/fuel ratio to minimize exhaust emissions is 14.7 to 1, which allows the catalytic converter to
operate most efficiently. Because of the constant measuring and adjusting of the air/fuel ratio, the fuel injection system
is called a “closed loop” system.
The ECM uses voltage inputs from several sensors to determine how much fuel to provide to the engine. The fuel is
delivered under one of several conditions, called ‘‘modes”.
Starting Mode
When the ignition is turned ON, the ECM turns the fuel pump relay on for 1 second. The fuel pump then builds fuel
pressure. The ECM also checks the Engine Coolant Temperature (ECT) sensor and the Throttle Position (TP) sensor
and determines the proper air/fuel ratio for starting the engine. This ranges from 1.5 to 1 at -- 36°C(--33°F) coolant
temperature to 14.7 to 1 at 94°C (201°F) coolant temperature. The ECM controls the amount of fuel delivered in the
starting mode by changing how long the fuel injector is turned on and off. This is done by ‘‘pulsing” the fuel injectors for
very short times.
Run Mode
The run mode has two conditions called ‘‘open loop” and ‘‘closed loop”.
Open Loop
When the engine is first started and it is above 690 rpm, thesystem goes into “open loop” operation. In “open loop”, the
ECM ignores the signal from the HO2S and calculates the air/fuel ratio based on inputs from the ECT sensor and the
MAF sensor. The ECM stays in “open loop” until the following conditions are met:
DThe O2 has a varying voltage output, showing that it is hot enough to operate properly.
DThe ECT sensor is above a specified temperature (22.5°C).
DA specific amount of time has elapsed after starting the engine.
Closed Loop
The specific values for the above conditions vary with different engines and are stored in the Electronically Erasable
Programmable Read -- Only Memory (EEPROM). When these conditions are met, thesystem goes into “closed loop”
operation. In “closed loop”, the ECM calculates the air/fuel ratio (fuel injector on-- time) based on the signals from the
O2 sensors. This allows the air/fuel ratio to stay very close to 14.7 to 1.
Acceleration Mode
The ECM responds to rapid changes in throttle position and airflow and provides extra fuel.
Deceleration Mode
The ECM responds to changes in throttle position and airflow and reduces the amount of fuel. When deceleration is
very fast, the ECM can cut off fuel completely for short periods of time.
Page 462 of 2053
1F2 -- 44 M161 ENGINE CONTROLS
D AEW OO M Y_2000
Measure the Fuel Delivery from the Fuel Pump
1. Disconnect the return pipe from fuel distributor and insert the appropriate hose into it.
2. Place the hose end into the beaker with the minimum capacity of 1 Liter
3. Turn the ignition switch to “ON” position.
4. Connect the terminal No. 33 and No. 5 of ECM with a service wire.
5. Measure the fuel delivery from the fuel pump
Specified Value
1 Liter/max. 35 sec.
Notice:Check the fuel filter and fuel line when the fuel delivery is not within specified value.
Measure the Current Consumption of Fuel Pump
1. Remove the fuel pump relay from fuse and relay box in trunk, and turn the ignition switch to “ON” position.
2. Using a multimeter, measure the current consumption by connecting the terminal No. 30 and No. 87 of the fuel
pump relay connector.
Specified Value
5~9A
Notice:Replace the fuel pump relay if the measured value is over 9 A.
Page 478 of 2053

1F2 -- 60 M161 ENGINE CONTROLS
D AEW OO M Y_2000
HOT FILM AIR MASS (HFM) SENSOR
YAA1F570
The Hot Film Air Mass (HFM) sensor with recognition of flow direction related to pulsating flow is designed for record-
ing load on Engine Control Module (ECM) by measuring the output voltage proportional to the reference voltage of the
ECM.
Mass Air Flow Sensor
Mass Air Flow (MAF) is a thermal flow meter whose sensor element with its temperature sensors and heating area is
exposed to the MAF to be measured. A heating area located in the center of a thin membrane is controlled to an over --
temperature by a heating resistor and a temperature sensor of this membrane. And the value of over -- temperature
depends on the temperature of the in-- flowing air.
Two temperature sensors on upstream and downstream of the heating area show the same temperature without in-
coming flow. With incoming flow, upstream part is cooled down but downstream temperature retains its temperature
more or less due to the air heated up in the heating area. This temperature difference in quantity and direction depends
on the direction of the incoming flow.
ECM modulates the flow of heating current to maintain the temperature differential between the heated film and the
intake air at a constant level. The amount of heating current required to maintain the temperature thus provides an
index for the MAF. This concept automatically compensates for variations in air density, as this is one of the factors that
determines the amount of warmth that the surrounding air absorbs from the heated element. MAF sensor is located
between the air filter and the throttle valve.
Under high fuel demands, the MAF sensor reads a high mass flow condition, such as Wide Open Throttle (WOT). The
ECM uses this information to enrich the mixture, thus increasing the fuel injector on-- time, to provide the correct
amount of fuel. When decelerating, the mass flow decreases. This mass flow change is sensed by the MAF sensor
and read by the ECM, which then decreases the fuel injector on-- time due to the low fuel demand conditions.
To facilitate the installation of the HFM in the intake passage, lubricating agents may be used. However, when lubri-
cants are used care must be taken to ensure that they do not enter the flow passage and cannot be sucked in with the
air flow.
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1F2 -- 96 M161 ENGINE CONTROLS
D AEW OO M Y_2000
YAA1F550
8. Using the fuel tank cap wrench 661 589 00 46 00,
remove the locking cap.
9. Remove the pump from the fuel tank.
Notice:Check the condition of the seal and replace if
necessary. Drain the fuel before removing the pump.
10. Perform an operational check of the fuel pump.
11. Installation should follow the removal procedure in
the reverse order.
YAA1F190
FUEL FILTER
Removal and Installation Procedure
1. Disconnect the negative battery cable.
Caution: The fuel system is under pressure. To
avoid fuel spillage and the risk of personal injury or
fire, it is necessary to relieve the fuel system pres -
sure before disconnecting the fuel lines.
2. Relieve the fuel system pressure. Refer to “Dis-
charging the Pressure in Fuel System” in this sec-
tion.
3. Disconnect the fuel lines from the fuel filter.
Installation Notice
Tightening Torque
28 NSm (21 lb-ft)
4. Remove the fuel filter mounting bracket bolt .
Installation Notice
Tightening Torque
6NSm (53 lb-in)
Notice:Place the fuel pump pad. There may be a corro-
sion due to the contact between the fuel filter and the
bracket.
5. Remove the fuel filter.
6. Install the fuel filter.
7. Perform a leak test of the fuel filter.
8. Installation should follow the removal procedure in
the reverse order.
Page 537 of 2053
1A3 -- 2 GENERAL ENGINE INFORMATION
D AEW OO M Y_2000
ENGINE SPECIFICATIONS (Cont’d)
ApplicationOM662LAOM661LA
Idle Speed (rpm)720 -- 820750 -- 850
Fuel Injection Pressure (bar)135 -- 143135 -- 143
Oil Capacity (liter)8.0 -- 9.56.5 -- 8.0
Lubrication TypeForced by Gear PumpForced by Gear Pump
Oil Filter TypeCombined Full-- Flow and Partial
Flow FilterCombined Full-- Flow and Partial
Flow Filter
FuelDieselDiesel
Page 553 of 2053
OM600 ENGINE MECHANICAL 1B3 -- 3
D AEW OO M Y_2000
Cylinder Head
ApplicationNSmLb-- FtLb-- In
Prechamber Threaded Ring13096--
Cylinder Head Cover Bolt10--89
Fuel Injsction Pipe Nut1813--
Socket Bolt2518--
Fuel Filter Pipe Bolt2518--
Idle Pulley Bolt2317--
Damper Bolt2115--
Camshaft Bearing Cap Bolt2518--
Camshaft Sprocket Bolt25 / 90_18 / 90_--
Exhaust Pipe Bolt& Nut2518--
Chain Tensioner8059--
Injection Nozzle4030--
Intake Manifold Not2518--
Injection Nozzle Pipe Not1813--
Oil Dipstick Tube Bolt10--89
Screw Plug M18 x 155037--
Cam Support & Shaft
ApplicationNSmLb-- FtLb-- In
Stud Bolt12--106
Exhaust Manifold Not2518--
CamShaft Bearing Cap Bolt2518--
12-- Sided Bolt (M11)25 / 90_18 / 90_--
Timing Cover
ApplicationNSmLb-- FtLb-- In
Oil Pan Bolt -- Socket Bolt10--89
Oil Pan Bolt--M610--89
Oil Pan Bolt--M232317--
Belt Pulley Bolt3224--
Guide Pulley Bolt4--35
Guide Pulley Bracket Nut2317--
Chain Tensioner8059--
Tesioning Lever Bolt2317--
Page 565 of 2053
1B3 -- 16 OM600 ENGINE MECHANICAL
D AEW OO M Y_2000
16. Remove the power steering pump lines.
Notice
Completely drain the fluid.
17. Disconnect the fuel feed line with prefilter from the
feed pump on injection pump.
18. Vehicle with automatic transmission.
Remove the hydraulic lines (19, 20) from oil cooler
(2).
19. Disconnect the engine harness.
20. Disconnect the preheating time relay cable.
Page 566 of 2053
OM600 ENGINE MECHANICAL 1B3 -- 17
D AEW OO M Y_2000
21. Remove the fuel lines from the fuel filter and cover
the filter with plug.
22. Disconnect the brake booster hose from vacuum
pump.
23. Disconnect the other vacuum lines.
24. Disconnect the ground cable.
25. Disconnect the generator wires.
26. Disconnect the starter motor wires and remove the
starter motor.