
SEF933W
SEF284G
+Method B
a) Remove No. 1 ignition coil.
b) Connect No. 1 ignition coil and No. 1 spark plug with suitable
high-tension wire as shown, and attach timing light clamp to
this wire.
c) Check ignition timing.
SEF166Y
PreparationNJEC0592+Make sure that the following parts are in good order.
a)Battery
b)Ignition system
c)Engine oil and coolant levels
d)Fuses
e)ECM harness connector
f)Vacuum hoses
g)Air intake system
(Oil filler cap, oil level gauge, etc.)
BASIC SERVICE PROCEDUREQG
How to Check Idle Speed and Ignition Timing (Cont'd)
EC-42

TEST ITEM CONDITION JUDGEMENT CHECK ITEM (REMEDY)
IACV-AAC/V
OPENING+Engine: After warming up, idle
the engine.
+Change the IACV-AAC valve
opening steps using CONSULT-
II.Engine speed changes according
to the opening steps.+Harness and connector
+IACV-AAC valve
POWER BAL-
ANCE+Engine: After warming up, idle
the engine.
+Air conditioner switch ªOFFº
+Shift lever ªNº
+Cut off each injector signal one
at a time using CONSULT-II.Engine runs rough or dies.+Harness and connector
+Compression
+Injectors
+Power transistor
+Spark plugs
+Ignition coils
COOLING FAN+Ignition switch: ON
+Turn the cooling fan ªONº and
ªOFFº using CONSULT-II.Cooling fan moves and stops.+Harness and connector
+Cooling fan motor
ENG COOLANT
TEMP+Engine: Return to the original
trouble condition
+Change the engine coolant tem-
perature indication using CON-
SULT-II.If trouble symptom disappears, see
CHECK ITEM.+Harness and connector
+Engine coolant temperature sen-
sor
+Fuel injectors
FUEL PUMP
RELAY+Ignition switch: ON
(Engine stopped)
+Turn the fuel pump relay ªONº
and ªOFFº using CONSULT-II
and listen to operating sound.Fuel pump relay makes the operat-
ing sound.+Harness and connector
+Fuel pump relay
EGR VOL
CONT/V
(If so equipped)+Engine: After warming up, idle
the engine.
+Change the EGR volume control
valve opening step using CON-
SULT-II.Engine speed changes according
to the opening step.+Harness and connector
+EGR volume control valve
VALVE TIMING
SOL+Ignition switch: ON
+Turn intake valve timing control
solenoid valve ªONº and ªOFFº
using CONSULT-II and listen for
operating sound.Intake valve timing control solenoid
valve makes an operating sound.+Harness and connector
+Intake valve timing control sole-
noid valve
PURG VOL
CONT/V+Engine: After warming up, idle
the engine.
+Change the EVAP canister
purge volume control solenoid
valve opening percent using
CONSULT-II.Engine speed changes according
to the opening percent.+Harness and connector
+EVAP canister purge volume
control solenoid valve
DTC AND SRT CONFIRMATION MODENJEC0034S08This mode is not available for models without Euro-OBD system.
SRT STATUS ModeNJEC0034S0801For details, refer to ªSYSTEM READINESS TEST (SRT) CODEº,
EC-60.
SRT Work Support ModeNJEC0034S0803This mode enables a technician to drive a vehicle to set the SRT
while monitoring the SRT status.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
CONSULT-II (Cont'd)
EC-89

MEF036D
SEF233G
SEF234G
IntroductionNJEC0036The engine has an ECM to control major systems such as fuel
control, ignition control, idle air control system, etc. The ECM
accepts input signals from sensors and instantly drives actuators.
It is essential that both input and output signals are proper and
stable. At the same time, it is important that there are no problems
such as vacuum leaks, fouled spark plugs, or other problems with
the engine.
It is much more difficult to diagnose a problem that occurs intermit-
tently rather than continuously. Most intermittent problems are
caused by poor electric connections or improper wiring. In this
case, careful checking of suspected circuits may help prevent the
replacement of good parts.
A visual check only may not find the cause of the problems. A road
test with CONSULT-II (or GST) or a circuit tester connected should
be performed. Follow the ªWork Flowº on EC-96.
Before undertaking actual checks, take a few minutes to talk with
a customer who approaches with a driveability complaint. The cus-
tomer can supply good information about such problems, espe-
cially intermittent ones. Find out what symptoms are present and
under what conditions they occur. A ªDiagnostic Worksheetº like the
example on next page should be used.
Start your diagnosis by looking for ªconventionalº problems first.
This will help troubleshoot driveability problems on an electronically
controlled engine vehicle.
SEF907L
DIAGNOSTIC WORKSHEETNJEC0036S01There are many operating conditions that lead to the malfunction
of engine components. A good grasp of such conditions can make
trouble-shooting faster and more accurate.
In general, each customer feels differently about a problem. It is
important to fully understand the symptoms or conditions for a
customer complaint.
Utilize a diagnostic worksheet like the one on the next page in order
to organize all the information for troubleshooting.
Some conditions may cause the malfunction indicator lamp to
come on steady or blink and DTC to be detected.
Example:
Vehicle ran out of fuel, which caused the engine to misfire.
TROUBLE DIAGNOSIS Ð INTRODUCTIONQG
EC-94

On Board Diagnosis LogicNJEC0202If a misfire occurs, the engine speed will fluctuate. If the fluctuation is detected by the crankshaft position sen-
sor (POS), the misfire is diagnosed.
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)
When a misfire is detected which will overheat and damage the three way catalyst, the MI will start blink-
ing; even during the first trip. In this condition, ECM monitors the misfire every 200 revolutions.
If the misfire frequency decreases to a level that will not damage the three way catalyst, the MI will change
from blinking to lighting up. (After the first trip detection, the MI will light up from engine starting. If a mis-
fire is detected that will cause three way catalyst damage, the MI will start blinking.)
2. Two Trip Detection Logic (Exhaust quality deterioration)
When a misfire that will not damage the three way catalyst (but will affect exhaust emission) occurs, the
MI will light up based on two trip detection logic. In this condition, ECM monitors the misfire for every 1,000
revolutions of the engine.
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0300
0300+Multiple cylinders misfire.+Improper spark plug
+Insufficient compression
+Incorrect fuel pressure
+EGR volume control valve
+The injector circuit is open or shorted
+Injectors
+Intake air leak
+Insufficient ignition spark
+Lack of fuel
+Heated oxygen sensor 1 (front) P0301
0301+No. 1 cylinder misfires.
P0302
0302+No. 2 cylinder misfires.
P0303
0303+No. 3 cylinder misfires.
P0304
0304+No. 4 cylinder misfires.
SEF058Y
DTC Confirmation ProcedureNJEC0203CAUTION:
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.
2) Start engine and warm it up to normal operating temperature.
3) Turn ignition switch ªOFFº and wait at least 9 seconds.
4) Start engine again and drive at 1,500 - 3,000 rpm for at least
3 minutes.
Hold the accelerator pedal as steady as possible.
NOTE:
Refer to the freeze frame data for the test driving conditions.
5) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-263.
With GST
Follow the procedure ªWith CONSULT-IIº above.
DTC P0300 - P0304 NO.4-1CYLINDER MISFIRE, MULTIPLE CYLINDER
MISFIRE
QG
On Board Diagnosis Logic
EC-262

6 CHECK IGNITION SPARK
1. Turn Ignition switch ªOFFº.
2. Disconnect ignition coil assembly from rocker cover.
3. Connect a known good spark plug to the ignition coil assembly.
4. Place end of spark plug against a suitable ground and crank engine.
5. Check for spark.
SEF575Q
OK or NG
OK©GO TO 7.
NG©Check ignition coil, power transistor and their circuits. Refer to EC-451.
7 CHECK SPARK PLUGS
Remove the spark plugs and check for fouling, etc.
SEF156I
OK or NG
OK©GO TO 8.
NG©Repair or replace spark plug(s) with standard type one(s). For spark plug type, refer to
EM-18, ªChecking and changingº.
8 CHECK COMPRESSION PRESSURE
Refer to EM section.
+Check compression pressure.
Standard:
1,324 kPa (13.24 bar, 13.5 kg/cm
2, 192 psi)/350 rpm
Minimum:
1,128 kPa (11.28 bar, 11.5 kg/cm
2, 164 psi)/350 rpm
Difference between each cylinder:
98 kPa (0.98 bar, 1.0 kg/cm
2, 14 psi)/350 rpm
OK or NG
OK©GO TO 9.
NG©Check pistons, piston rings, valves, valve seats and cylinder head gaskets.
DTC P0300 - P0304 NO.4-1CYLINDER MISFIRE, MULTIPLE CYLINDER
MISFIRE
QG
Diagnostic Procedure (Cont'd)
EC-265

SEF184UD
On Board Diagnosis LogicNJEC0240The ECM monitors the switching frequency ratio of heated oxygen
sensors 1 (front) and 2 (rear).
A three way catalyst with high oxygen storage capacity will indicate
a low switching frequency of heated oxygen sensor 2 (rear). As
oxygen storage capacity decreases, the heated oxygen sensor 2
(rear) switching frequency will increase.
When the frequency ratio of heated oxygen sensors 1 (front) and
2 (rear) approaches a specified limit value, the three way catalyst
malfunction is diagnosed.
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0420
0420+Three way catalyst does not operate properly.
+Three way catalyst does not have enough oxygen stor-
age capacity.+Three way catalyst
+Exhaust tube
+Intake air leaks
+Injectors
+Injector leaks
+Spark plug
+Improper ignition timing
SEF847Y
SEF848Y
SEF560X
DTC Confirmation ProcedureNJEC0241CAUTION:
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
TESTING CONDITION:
+Open engine hood before conducting following proce-
dure.
+Do not hold engine speed more than specified minutes
below.
1) Turn ignition switch ªONº.
2) Select ªDTC & SRT CONFIRMATIONº then ªSRT WORK SUP-
PORTº mode with CONSULT-II.
3) Start engine.
4) Rev engine up to 3,000±500 rpm and hold it for 3 consecutive
minutes then release the accelerator pedal completely.
If ªCOMPLETEDº appears on the CONSULT-II screen, go to
step 7.
5) Wait 5 seconds at idle.
6) Rev engine up to 2,500±500 rpm and maintain it until ªINCMPº
of CATALYST changes to ªCMPLTº (it will take approximately
5 minutes.)
If not ªCMPLTº, stop engine and cool it down to less than 70ÉC
(158ÉF) and then retest from step 1.
7) Select ªSELF-DIAG RESULTSº mode with CONSULT-II.
8) Confirm that the 1st trip DTC is not detected.
If the 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-300.
DTC P0420 THREE WAY CATALYST FUNCTIONQG
On Board Diagnosis Logic
EC-299

5 CHECK INJECTORS
1. Refer to Wiring Diagram for Injectors, EC-447.
2. Stop engine and then turn ignition switch ªONº.
3. Check voltage between ECM terminals 101, 103, 105 and 107 and ground with CONSULT-II or tester.
SEF075X
Battery voltage should exist.
OK or NG
OK©GO TO 6.
NG©Perform ªDiagnostic Procedureº INJECTOR, EC-448.
6 CHECK IGNITION SPARK
1. Disconnect ignition coil assembly from rocker cover.
2. Connect a known good spark plug to the ignition coil assembly.
3. Place end of spark plug against a suitable ground and crank engine.
4. Check for spark.
SEF575Q
OK or NG
OK©GO TO 7.
NG©Check ignition coil, power transistor and their circuits. Refer to EC-451.
7 CHECK INJECTOR
1. Turn ignition switch ªOFFº.
2. Remove injector assembly. Refer to EC-39.
Keep fuel hose and all injectors connected to injector gallery.
3. Disconnect camshaft position sensor harness connector.
4. Turn ignition switch ªONº.
Make sure fuel does not drip from injector.
OK or NG
OK (Does not drip)©GO TO 8.
NG (Drips)©Replace the injector(s) from which fuel is dripping.
DTC P0420 THREE WAY CATALYST FUNCTIONQG
Diagnostic Procedure (Cont'd)
EC-302