1F2 -- 46 M161 ENGINE CONTROLS
D AEW OO M Y_2000
FUEL INJECTOR
YAA1F0C0
The Multipoint Fuel Injection (MFI) assembly is a solenoid -- operated device controlled by the Engine Control Module
(ECM) that meters pressurized fuel to an each individual cylinder. The injector sprays the fuel, in precise quantities at a
point in time determined by the ECM, directly toward the cylinder intake valve. ECM energizes the fuel injector solenoid
to lift the needle valve and to flow the fuel through the orifice. This injector ’s discharge orifice is calibrated to meet the
effective fuel atomization necessary for both ensuring the maximum homogeneity in the air -- fuel mixture and holding
the condensation along the walls of the intake tract to a minimum.
Fuel enters the top feed injector from above and flows through its vertical axis. The lower end extends into the intake
valve. Fuel from the tip is directed at the intake valve, causing it to become further atomized and vaporized before
entering the combustion chamber.
A fuel injector which is stuck partially open would cause a loss of fuel pressure after the engine is shut down. Also, an
extended crank time would be noticed on some engines. Dieseling could also occur because some fuel could be deliv-
ered to the engine after the ignition is turned off.
1F2 -- 48 M161 ENGINE CONTROLS
D AEW OO M Y_2000
Failure
CodeDescriptionTrouble AreaMaintenance Hint
77No. 3 injector short
circuit to ground or open
When malfunction of injector
circuit
Injector #3 short circuit to
ground or openDInspection the ECM pin 65 about short
circuit or open with bad contact
DInspection the injector
DInspection the ECM
78No. 4 injector short
circuit to battery
When malfunction of injector
circuit
Injector #4 short circuit to
powerDInspection the power to injector #4 or
bad contact
DInspection the injector
DInspection the ECM
79No. 4 injector short
circuit to ground or open
When malfunction of injector
circuit
Injector #4 short circuit to
ground or openDInspection the ECM pin 66 about short
circuit or open with bad contact
DInspection the injector
DInspection the ECM
YAA1F420YAA1F430
Injector Spray Pattern Check
1. Turn the ignition switch OFF.
2. Remove the fuel injector connectors.
3. Remove the fuel distributor and injector with a unit. At this time, do not remove the supply and return line.
Notice:Prepare the beaker for taking the fuel.
4. Connect the shop made cable to the injector with a firing order.
5. Connect the other end of shop made cable to the positive battery cable and negative battery cable.
6. Turn the ignition switch ON.
7. Check the injector for normal spray pattern as shown in the figure. Check injector for leaks or later drop
Injector Resistance Inspection
1. Turn the ignition switch OFF.
2. Remove the fuel injector connectors.
3. Measure the fuel injector coil resistance using a multimeter.
Specified Value
14 ~ 17Ω
Notice:Replace the fuel injector if the measured value is out of the specified values. Check the connector and wire
connection between the ECM and the injector if the measured values are normal.
M161 ENGINE CONTROLS 1F2 -- 49
D AEW OO M Y_2000
Injector Pulse Width Inspection
1. Turn the ignition switch OFF.
2. Install the scan tool.
3. Turn the ignition switch ON.
4. Monitor the “INJECTION TIME” with a scan tool.
Cranking
8.0 ms
Engine Idle3~5ms
Wide Open Throttle (WOT)14 ms
M161 ENGINE CONTROLS 1F2 -- 51
D AEW OO M Y_2000
KAB1F230
Failure
CodeDescriptionTrouble AreaMaintenance Hint
40Purge control valve
short circuit to batteryWhen short circuit to power
sourceDInspection the ECM pin 34 about short
circuitoropenwithbadcontact
41
Purge control valve
short circuit to ground or
openWhen short circuit to ground or
open
circuitor open withbadcontact
DInspection the source power of valve
DInspection the purge control solenoid
vale
54Purge control circuit
malfunctionWhen malfunction of purge
control : not workvale
DInspection the ECM
Test
YAA1F460
1. Maintain the normal temperature and idling state by
operating the engine.
2. Connect the ECM terminal No. 11 and No. 34 and
check for normal operation through the output waves
using oscilloscope.Notice:Test during purge control valve operation after
the minimum of 1 minute after the engine turned on.
3. Connect the ECM terminal No. 34 and No.10 and
check for current consumption during the ignition
switch ON.
Specified Value
0.3 ~ 0.5 A
4. Remove the line to canister and measure the pres-
sure with the vacuum pressure gauge.
Specified Value
> 500 mbar
(after approx. 1 min.)
purge control valve operates
at this time
Notice:Test while at normal temperature and at idling
state by operating the engine.
M161 ENGINE CONTROLS 1F2 -- 53
D AEW OO M Y_2000
Fuel Pressure Test
Tools Required
103 589 00 21 00 Fuel Pressure Gauge
1. Turn the ignition switch to “OFF” position.
2. Remove the fuel pressure test connector.
YAA1F700
3. Connect the fuel pressure gauge to the fuel pressure test connector.
4. Test the fuel pressure at idling by operating the engine using the fuel pressure gauge 103 589 00 21 00.
Vacuum Hose Connected (bar)
3.2~3.6
Vacuum Hose Disconnected (bar)3.7~4.2
5. Replace the pressure regulator diaphragm if out of the specification.
Internal Leakage Test
1. Connect the fuel pressure gauge 103 589 00 21 00 to
the fuel pressure test connector.
YAA1F0K0
2. Stop the engine for approximately 30 minutes and then check the fuel pressure changes.
Pressure change
Fuel pressure drops slowlyDFuel leakage at the injector
DFaulty fuel pressure regulator ’s diaphragm and O-ring
Fuel pressure drops rapidlyDFaulty check valve in the fuel pump
3. If there is no change in fuel pressure and maintain the following pressure over 30minutes, it is normal.
Fuel pressure (bar)
≥2.5
1F2 -- 56 M161 ENGINE CONTROLS
D AEW OO M Y_2000
INDUCTION SYSTEM
THROTTLE VALVE ACTUATOR
YAA1F540
The throttle actuator is actuated by the Engine Control Module (ECM) according to the position of the accelerator pedal
position.
It has two potentiometers which signal the position of the throttle valve to the ECM to enable it to recognize the various
engine load states.
Ignition “Off”
In the de-- energized states the throttle valve position is determined to be spring capsule.
Ignition “On”
When the ignition S/W on the servo motor in the throttle actuator is operated by the ECM. The throttle valve adopts a
position in line with the coolant temperature.
Closed position
In the closed throttle position, the servo motor controls engine speed by operating the throttle valve further (greater
mixture) or closing it further (reduced mixture), depending on coolant temperature and engine load. When this is done,
the throttle valve can be closed further by the servo motor overcoming the force of the spring capsule (mechanical end
stop). If the actuator is de-- energized, the throttle valve is resting against the spring capsule.
Consequently, the throttle valve opening is a constant 10-- 12°approximately.
At no load, this produces an engine speed of about 1,800 rpm
Driving
When driving (part/full throttle), the servo motor controls the throttle valve in line with the various load states and ac-
cording to the input signals from the pedal value sensor according to the input signals from the pedal value sensor
according to the position of the accelerator pedal.
The function of the EA (electronic accelerator) in the ECM determines the opening angle of the throttle valve through
the throttle actuator. Further functions are;
DIdle speed control
DCruise control
DReducing engine torque for ASR/ABS operation
DElectronic accelerator emergency running
DStoring faults
DData transfer through CAN
1F2 -- 58 M161 ENGINE CONTROLS
D AEW OO M Y_2000
Failure
CodeDescriptionTrouble AreaMaintenance Hint
126
Throttle position sensor
1 not plausible with
Throttle position sensor
2
When difference between
TPS 1 and TPS 2DMonitoring the actual values through
scan tool
DIns
pection the ECMpin 84, 85, 87,
127High permanent throttle
signalWhen failure of wiring
harness or actuator
DInspectiontheECMpin84,85,87,
112, 67, 68 about short circuit or open
with bad contact
Itiththttlltt
185
Mass air flow sensor
and throttle position
sensor failureWhen difference between
MAF and TPS signal
DInspection the throttle valve actuator
DInspection the ECM
Circuit Description
The ECM supplies a 5 volt reference signal and a ground to the TP sensor. The TP sensor sends a voltage signal back
to the ECM relative to the throttle plate opening. The voltage signalwill vary from approximately 0.3 ~ 0.9 volts at
closed throttle, to over 4.0 ~ 4.6 volts at Wide Open Throttle (WOT).
The TP sensors serve for engine load control according to the drive pedal command. Load adjustments independent of
the drive pedal command can be implemented; such functions are, for instance, idle control, speed control, drive slip
control, load shock damping, and similar functions.
When the actuator current fails, the throttle valve is returned to emergency operating position by a spring. The throttle
valve position, thereby the actuator drive position checkback is provided by two potentiometers. The motor positions
the throttle valve against the return spring force. Motor and return spring are two separate energy sources. Each of
them is able to position the throttle valve in emergency position alone. Throttle valve position checkback and monitor-
ing is provided by two actual value potentiometers connected to the engine control electronics.
Throttle Actuator Inspection
1. Turn the ignition switch to “ON” position.
2. Measure the TPS 1 signal voltage at the ECM pin No. 87 and TPS 2 signal voltage at the ECM pin No. 85.
Pedal PositionSpecified Value
TPS1Closed0.3 ~ 0.9 vTPS1Opened4.0 ~ 4.6 v
TPS2Closed4.0 ~ 4.6 vTPS2Opened0.3 ~ 0.9 v
Throttle Actuator DC Motor Inspection
1. Turn the ignition switch to “ON” position.
2. Measure the signal voltage between the ECM pin No. 67 and No. 68.
Application
Specified Value
Ignition “ON”0.8 ~ 2.3 v
Engine StatusIdling1.0 ~ 2.5 v
(Coolant temperature is over 70°C)
Throttle Actuator DC Motor Resistance
1. Turn the ignition switch to “OFF” position.
2. Measure the resistance between the ECM pin No. 67 and No. 68.
Specified Value
<10Ω
M161 ENGINE CONTROLS 1F2 -- 63
D AEW OO M Y_2000
Mass Air Flow Sensor Input Voltage Inspection
1. Turn the ignition switch to “ON” position.
2. Measure the signal voltage between the ECM pin No. 103 and No. 104.
Application
Specified Value
Ignition “ON”0.9 ~ 1.1 v
Engine StatusIdling1.3 ~ 1.7 v
(Coolant temperature is over 70°C)
Notice:If the measured value is not within the specified value, the possible cause may be in cable or MAF sensor in
itself. Perform the 5 volt power supply inspection procedures.
Mass Air Flow Sensor 5 volt Power Supply Inspection
1. Turn the ignition switch to “OFF” position.
2. Disconnect the HFM sensor connector.
3. Turn the ignition switch to “ON” position.
4. Measure the voltage between the ECM pin No. 108 and MAF sensor connecter terminal No. 3.
Specified Value
4.7~5.2v
Notice:If the measured value is not within the specified value, the possible cause may be in cable or ECM coupling.
5. Measure the voltage between the ECM pin No. 105 and MAF sensor connecter terminal No. 4.
Specified Value
4.7~5.2v
Notice:If the measured value is not within the specified value, the possible cause may be in cable or ECM coupling.
Mass Air Flow Sensor 12 volt Power Supply Inspection
1. Turn the ignition switch to “OFF” position.
2. Disconnect the HFM sensor connector.
3. Turn the ignition switch to “ON” position.
4. Measure the voltage between the ECM pin No. 105 and MAF sensor connecter terminal No. 2.
Specified Value
11 ~ 14 v
Notice:If the measured value is not within the specified value, the possible cause may be in cable or Over Voltage
Protection Relay (OVPR).