On Board Diagnosis LogicNCEC0188With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the
theoretical mixture ratio based on the mixture ratio feedback signal from the Heated oxygen sensor 1 (front).
The ECM calculates the necessary compensation to correct the offset between the actual and the theoretical
ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MI (2 trip detection logic).
Sensor Input Signal to ECMECM func-
tionActuator
Heated oxygen sensor 1 (front)Density of oxygen in exhaust gas
(Mixture ratio feedback signal)Fuel injec-
tion & mix-
ture ratio
controlInjectors
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0171
0171IFuel injection system does not operate properly.
IThe amount of mixture ratio compensation is too large.
(The mixture ratio is too lean.)IIntake air leaks
IHeated oxygen sensor 1 (front)
IInjectors
IExhaust gas leaks
IIncorrect fuel pressure
ILack of fuel
IMass air flow sensor
DTC Confirmation ProcedureNCEC0189NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
With CONSULT-II
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Turn ignition switch ªONº and select ªSELF-LEARNING CONTº
in ªWORK SUPPORTº mode with CONSULT-II.
4) Clear the self-learning control coefficient by touching ªCLEARº.
5) Select ªDATA MONITORº mode with CONSULT-II.
6) Start engine again and let it idle for at least 10 minutes.
The 1st trip DTC P0171 should be detected at this stage, if a
malfunction exists. If so, go to ªDiagnostic Procedureº, EC-QG-
211.
7) If it is difficult to start engine at step 6, the fuel injection sys-
tem has a malfunction.
8) Crank engine while depressing accelerator pedal. If engine
starts, go to ªDiagnostic Procedureº, EC-QG-211. If engine
does not start, visually check for exhaust and intake air leak.
With GST
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Disconnect mass air flow sensor harness connector. Then
restart and run engine for at least 3 seconds at idle speed.
4) Stop engine and reconnect mass air flow sensor harness con-
nector.
5) Select ªMODE 7º with GST. Make sure 1st trip DTC P0100 is
detected.
6) Select ªMODE 4º with GST and erase the 1st trip DTC P0100.
SEF652Y
NEF068A
SEF995W
DTC P0171 FUEL INJECTION SYSTEM FUNCTION
(LEAN SIDE)QG16I18DE
On Board Diagnosis Logic
EC-208
4 CHECK FUEL PRESSURE
1. Release fuel pressure to zero.
Refer to EC-QG-29.
2. Install fuel pressure gauge and check fuel pressure.
At idling:
When fuel pressure regulator valve vacuum hose is connected.
235 kPa (2.35 bar, 2.4 kg/cm
2, 34 psi)
When fuel pressure regulator valve vacuum hose is disconnected.
294 kPa (2.94 bar, 3.0 kg/cm
2, 43 psi)
OK or NG
OK©GO TO 6.
NG©GO TO 5.
5 DETECT MALFUNCTIONING PART
Check the following.
IFuel pump and circuit Refer to EC-QG-336.
IFuel pressure regulator Refer to EC-QG-30.
IFuel lines Refer to ªENGINE MAINTENANCEº in MA section.
IFuel filter for clogging
©Repair or replace.
6 CHECK MASS AIR FLOW SENSOR
With CONSULT-II
Check ªMASS AIR FLOWº in ªDATA MONITORº mode with CONSULT-II.
at idling: 1.0 - 4.0 g×m/sec
at 2,500 rpm: 5.0 - 10.0 g×m/sec
With GST
Check mass air flow sensor signal in MODE 1 with GST.
at idling: 1.0 - 5.0 g×m/sec
at 2,500 rpm: 5.0 - 10.0 g×m/sec
OK or NG
OK©GO TO 7.
NG©Check connectors for rusted terminals or loose connections in the mass air flow sensor
circuit or engine grounds. Refer to EC-QG-110.
DTC P0171 FUEL INJECTION SYSTEM FUNCTION
(LEAN SIDE)QG16I18DE
Diagnostic Procedure (Cont'd)
EC-212
On Board Diagnosis LogicNCEC0192With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the
theoretical mixture ratio based on the mixture ratio feedback signal from the Heated oxygen sensor 1 (front).
The ECM calculates the necessary compensation to correct the offset between the actual and the theoretical
ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too rich.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MI (2 trip detection logic).
Sensor Input Signal to ECMECM func-
tionActuator
Heated oxygen sensor 1 (front)Density of oxygen in exhaust gas
(Mixture ratio feedback signal)Fuel injec-
tion & mix-
ture ratio
controlInjectors
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0172
0172IFuel injection system does not operate properly.
IThe amount of mixture ratio compensation is too large.
(The mixture ratio is too rich.)IHeated oxygen sensor 1 (front)
IInjectors
IExhaust gas leaks
IIncorrect fuel pressure
IMass air flow sensor
DTC Confirmation ProcedureNCEC0193NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
With CONSULT-II
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Turn ignition switch ªONº and select ªSELF-LEARN CON-
TROLº in ªWORK SUPPORTº mode with CONSULT-II.
4) Clear the self-learning control coefficient by touching ªCLEARº.
5) Select ªDATA MONITORº mode with CONSULT-II.
6) Start engine again and let it idle for at least 10 minutes.
The 1st trip DTC P0172 should be detected at this stage, if a
malfunction exists. If so, go to ªDiagnostic Procedureº, EC-QG-
218.
7) If it is difficult to start engine at step 6, the fuel injection sys-
tem has a malfunction.
8) Crank engine while depressing accelerator pedal. If engine
starts, go to ªDiagnostic Procedureº, EC-QG-218. If engine
does not start, remove ignition plugs and check for fouling, etc.
With GST
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Disconnect mass air flow sensor harness connector. Then
restart and run engine for at least 3 seconds at idle speed.
4) Stop engine and reconnect mass air flow sensor harness con-
nector.
5) Select ªMODE 7º with GST. Make sure 1st trip DTC P0100 is
detected.
6) Select ªMODE 4º with GST and erase the 1st trip DTC P0100.
SEF652Y
NEF068A
SEF995W
DTC P0172 FUEL INJECTION SYSTEM FUNCTION
(RICH SIDE)QG16I18DE
On Board Diagnosis Logic
EC-215
3 CHECK FUEL PRESSURE
1. Release fuel pressure to zero.
Refer to EC-QG-29.
2. Install fuel pressure gauge and check fuel pressure.
At idling:
When fuel pressure regulator valve vacuum hose is connected.
Approximately 235 kPa (2.35 bar, 2.4 kg/cm
2, 34 psi)
When fuel pressure regulator valve vacuum hose is disconnected.
Approximately 294 kPa (2.94 bar, 3.0 kg/cm
2, 43 psi)
OK or NG
OK©GO TO 5.
NG©GO TO 4.
4 DETECT MALFUNCTIONING PART
Check the following.
IFuel pump and circuit (Refer to EC-QG-336.)
IFuel pressure regulator (Refer to EC-QG-30.)
©Repair or replace.
5 CHECK MASS AIR FLOW SENSOR
With CONSULT-II
Check ªMASS AIR FLOWº in ªDATA MONITORº mode with CONSULT-II.
at idling: 1.0 - 4.0 g×m/sec
at 2,500 rpm: 5.0 - 10.0 g×m/sec
With GST
Check mass air flow sensor signal in MODE 1 with GST.
at idling: 1.0 - 4.0 g×m/sec
at 2,500 rpm: 5.0 - 10.0 g×m/sec
OK or NG
OK©GO TO 6.
NG©Check connectors for rusted terminals or loose connections in the mass air flow sensor
circuit or engine grounds. Refer to EC-QG-113.
DTC P0172 FUEL INJECTION SYSTEM FUNCTION
(RICH SIDE)QG16I18DE
Diagnostic Procedure (Cont'd)
EC-219
On Board Diagnosis LogicNCEC0202When a misfire occurs, the engine speed will fluctuate. If the engine speed fluctuates enough to cause the
CKP sensor signal to vary, The ECM can determine that a misfire is occurring.
Sensor Input Signal to ECM ECM function
Crankshaft position sensor (POS) Engine speed On board diagnosis of misfire
The misfire detection logic consists of the following two conditions.
1. One Trip Detection Logic (Three Way Catalyst Damage)
On the first trip that a misfire condition occurs that can damage the three way catalyst (TWC) due to
overheating, the MI will blink.
When a misfire condition occurs, the ECM monitors the CKP sensor signal every 200 engine revolutions
for a change.
When the misfire condition decreases to a level that will not damage the TWC, the MI will turn off.
If another misfire condition occurs that can damage the TWC on a second trip, the MI will blink.
When the misfire condition decreases to a level that will not damage the TWC, the MI will remain on.
If another misfire condition occurs that can damage the TWC, the MI will begin to blink again.
(After the first trip detection, the MI will light up from engine starting. If a misfire is detected that will cause
three way catalyst damage, the MI will start blinking.)
2. Two Trip Detection Logic (Exhaust quality deterioration)
For misfire conditions that will not damage the TWC (but will affect emissions), the MI will only light when
the misfire is detected on a second trip. During this condition, the ECM monitors the CKP sensor signal
every 1,000 engine revolutions.
A misfire malfunction can be detected on any one cylinder or on multiple cylinders.
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0300
0300IMultiple cylinders misfire.IImproper spark plug
IInsufficient compression
IIncorrect fuel pressure
IEGR volume control valve (If so equipped)
IThe injector circuit is open or shorted
IInjectors
IIntake air leak
IInsufficient ignition spark
ILack of fuel
IHeated oxygen sensor 1 (front) P0301
0301INo. 1 cylinder misfires.
P0302
0302INo. 2 cylinder misfires.
P0303
0303INo. 3 cylinder misfires.
P0304
0304INo. 4 cylinder misfires.
DTC Confirmation ProcedureNCEC0203CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
With CONSULT-II
1) Turn ignition switch ªONº, and select ªDATA MONITORº mode
with CONSULT-II.
NEF068A
DTC P0300 - P0304 NO.4-1CYLINDER MISFIRE,
MULTIPLE CYLINDER MISFIREQG16I18DE
On Board Diagnosis Logic
EC-222
9 CHECK FUEL PRESSURE
1. Install any parts removed.
2. Release fuel pressure to zero. Refer to EC-QG-29.
3. Install fuel pressure gauge and check fuel pressure.
SEF925W
At idle: Approx. 235 kPa (2.35 bar, 2.4 kg/cm2, 34 psi)
OK or NG
OK©GO TO 11.
NG©GO TO 10.
10 DETECT MALFUNCTIONING PART
Check the following.
IFuel pump and circuit Refer to EC-QG-336.
IFuel pressure regulator Refer to EC-QG-30.
IFuel lines Refer to ªENGINE MAINTENANCEº in MA section.
IFuel filter for clogging
©Repair or replace.
11 CHECK IGNITION TIMING
Perform ªBasic Inspectionº.
Refer to EC-QG-72.
OK or NG
OK©GO TO 12.
NG©1. Perform ªIdle Air Volume Learningº. Refer to EC-QG-33.
2. Check camshaft position sensor (PHASE) (EC-QG-238) and crankshaft position sen-
sor (POS) (EC-QG-232).
12 CHECK HEATED OXYGEN SENSOR 1 (FRONT)
Refer to ªComponent Inspectionº, EC-QG-231.
OK or NG
OK©GO TO 13.
NG©Replace Heated oxygen sensor 1 (front).
DTC P0300 - P0304 NO.4-1CYLINDER MISFIRE,
MULTIPLE CYLINDER MISFIREQG16I18DE
Diagnostic Procedure (Cont'd)
EC-226
Component DescriptionNCEC0513The valve timing control system is utilized to control intake valve
opening and closing timing. Engine coolant temperature signals,
engine speed and throttle position are used to determine intake
valve timing.
The intake camshaft sprocket position is regulated by oil pressure
controlled by the intake valve timing control.
When ECM sends ON signal to intake valve timing control solenoid
valve, oil pressure is transmitted to camshaft sprocket. Then, intake
side camshaft is advanced.
OperationNCEC0514
Engine operating condition
Intake valve tim-
ing control sole-
noid valveIntake valve
opening and
closing timeValve overlap
Engine coolant
temperatureEngine speed B/FUEL SCHDL Neutral switch
20ÉC (68ÉF) -
70ÉC (158ÉF)
1,150 - 4,600
rpmAbove 3 msec
OFF ON Advance Increased
Above 70ÉC
(158ÉF)Above 7 msec
Conditions other than those above OFF Normal Normal
CONSULT-II Reference Value in Data Monitor
Mode
NCEC0515
MONITOR ITEM CONDITION SPECIFICATION
INT/V SOL-B1IEngine: After warming upIdle OFF
Revving engine with full throttle
opening (Under 4,600 rpm)ON
ECM Terminals and Reference ValueNCEC0516Specification data are reference values and are measured between each terminal and engine ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
1 Y/RIntake valve timing control
solenoid valveIgnition ªONºBATTERY VOLTAGE
(11 - 14V)
On Board Diagnosis LogicNCEC0517
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P 1111
1111IAn improper voltage signal is entered to ECM through
intake valve timing control solenoid valve.IHarness or connectors
(The intake valve timing control solenoid valve
circuit is open or shorted.)
IIntake valve timing control solenoid valve
SEF095X
D T C P 1111 I N TA K E VA LV ETIMING CONTROL
SOLENOID VALVEQG16I18DE
Component Description
EC-284
Diagnostic ProcedureNCEC0448
1 CHECK OVERALL FUNCTION
1. Turn ignition switch ªONº.
2. Pinch fuel feed hose with fingers.
SEF143XFuel pressure pulsation should be felt on the fuel feed hose for 1 second after ignition switch is turned ªONº.
OK or NG
OK©INSPECTION END
NG©GO TO 2.
2 CHECK POWER SUPPLY
1. Turn ignition switch ªOFFº.
2. Disconnect fuel pump relay.
SEF071X3. Turn ignition switch ªONº.
4. Check voltage between terminals 1, 3 and ground with CONSULT-II or tester.
SEF144XVoltage: Battery voltage
OK or NG
OK©GO TO 4.
NG©GO TO 3.
FUEL PUMPQG16I18DE
Diagnostic Procedure
EC-339