Page 1025 of 2267
Diagnostic ProcedureNCEC0204
1 CHECK FOR INTAKE AIR LEAK
1. Start engine and run it at idle speed.
2. Listen for the sound of the intake air leak.
OK or NG
OK©GO TO 2.
NG©Discover air leak location and repair.
2 CHECK FOR EXHAUST SYSTEM CLOGGING
Stop engine and visually check exhaust tube, three way catalyst and muffler for dents.
OK or NG
OK©GO TO 3.
NG©Repair or replace it.
3 PERFORM POWER BALANCE TEST
With CONSULT-II
1. Perform ªPOWER BALANCEº in ªACTIVE TESTº mode.
NEF105A2. Is there any cylinder which does not produce a momentary engine speed drop?
Without CONSULT-II
When disconnecting each injector harness connector one at a time, is there any cylinder which does not produce a momentary engine
speed drop?
SEF233X
YesorNo
Ye s©GO TO 5.
No©GO TO 8.
Remove to
test other injectors
Injector harness
connector (for No. 2 cylinder)
DTC P0300 - P0304 NO.4-1CYLINDER MISFIRE,
MULTIPLE CYLINDER MISFIRESR20DE
Diagnostic Procedure
EC-225
Page 1026 of 2267
4 CHECK INJECTOR
Does each injector make an operating sound at idle?
MEC703B
YesorNo
Ye s©GO TO 6.
No©Check injector(s) and circuit(s). Refer to EC-SR-304.
5 CHECK IGNITION SPARK
1. Turn Ignition switch ªOFFº.
2. Disconnect ignition wire from spark plug.
3. Connect a known good spark plug to the ignition wire.
4. Place end of spark plug against a suitable ground and crank engine.
5. Check for spark.
SEF282G
OK or NG
OK©GO TO 8.
NG©GO TO 7.
6 CHECK IGNITION WIRES
Refer to ªComponent Inspectionº, EC-SR-229.
OK or NG
OK©Check distributor rotor head for incorrect parts. Check ignition coil, power transistor and
their circuits. Refer to EC-SR-310.
NG©Replace.
Ignition wire
Spark plug
DTC P0300 - P0304 NO.4-1CYLINDER MISFIRE,
MULTIPLE CYLINDER MISFIRESR20DE
Diagnostic Procedure (Cont'd)
EC-226
Page 1027 of 2267

7 CHECK SPARK PLUGS
Remove the spark plugs and check for fouling, etc.
SEF156I
OK or NG
OK©GO TO 9.
NG©Repair or replace spark plug(s) with standard type one(s). For spark plug type, refer to
ªENGINE MAINTENANCEº in MA section.
8 CHECK COMPRESSION PRESSURE
Refer to EM section.
ICheck compression pressure.
Standard:
1,226 kPa (12.26 bar, 12.5 kg/cm
2, 178 psi)/300 rpm
Minimum:
1,030 kPa (10.30 bar, 10.5 kg/cm
2, 149 psi)/300 rpm
Difference between each cylinder:
98 kPa (0.98 bar, 1.0 kg/cm
2, 14 psi)/300 rpm
OK or NG
OK©GO TO 10.
NG©Check pistons, piston rings, valves, valve seats and cylinder head gaskets.
9 CHECK FUEL PRESSURE
1. Install any parts removed.
2. Release fuel pressure to zero. Refer to EC-SR-31.
3. Install fuel pressure gauge and check fuel pressure.
SEF194XAt idle:
Approx. 235 kPa (2.35 bar, 2.4 kg/cm2, 34 psi)
OK or NG
OK©GO TO 12.
NG©GO TO 11.
Fuel filter
DTC P0300 - P0304 NO.4-1CYLINDER MISFIRE,
MULTIPLE CYLINDER MISFIRESR20DE
Diagnostic Procedure (Cont'd)
EC-227
Page 1028 of 2267

10 DETECT MALFUNCTIONING PART
Check the following.
IFuel pump and circuit Refer to EC-SR-320.
IFuel pressure regulator Refer to EC-SR-32.
IFuel lines Refer to ªENGINE MAINTENANCEº in MA section.
IFuel filter for clogging
©Repair or replace.
11 CHECK IGNITION TIMING
Perform ªBasic Inspectionº, EC-SR-84.
OK or NG
OK©GO TO 13.
NG©Adjust ignition timing.
12 CHECK HEATED OXYGEN SENSOR 1 (FRONT)
Refer to ªComponent Inspectionº, EC-SR-154.
OK or NG
OK©GO TO 14.
NG©Replace heated oxygen sensor 1 (front).
13 CHECK MASS AIR FLOW SENSOR
With CONSULT-II
Check ªMASS AIR FLOWº in ªDATA MONITORº mode with CONSULT-II.
at idling: 2.5 - 5.0 g×m/sec
at 2,500 rpm: 7.1 - 12.5 g×m/sec
With GST
Check mass air flow sensor signal in MODE 1 with GST.
at idling: 2.5 - 5.0 g×m/sec
at 2,500 rpm: 7.1 - 12.5 g×m/sec
OK or NG
OK©GO TO 16.
NG©GO TO 15.
14 CHECK CONNECTORS
Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or engine grounds.
Refer to EC-SR-120.
OK or NG
NG©Repair or replace it.
15 CHECK SYMPTOM MATRIX CHART
Check items on the rough idle symptom in ªSymptom Matrix Chartº, EC-SR-94.
OK or NG
OK©GO TO 17.
NG©Repair or replace.
DTC P0300 - P0304 NO.4-1CYLINDER MISFIRE,
MULTIPLE CYLINDER MISFIRESR20DE
Diagnostic Procedure (Cont'd)
EC-228
Page 1029 of 2267
Component InspectionNCEC0576IGNITION WIRESNCEC0576S011. Inspect wires for cracks, damage, burned terminals and for
improper fit.
2. Measure the resistance of wires to their distributor cap termi-
nal. Move each wire while testing to check for intermittent
breaks.
Resistance:
4.5 - 6.7 kW/m (1.37 - 2.04 kW/ft) at 25ÉC (77ÉF)
If the resistance exceeds the above specification, inspect igni-
tion wire to distributor cap connection. Clean connection or
replace the ignition wire with a new one.
16 ERASE THE 1ST TRIP DTC
Some tests may cause a 1st trip DTC to be set.
Erase the 1st trip DTC from the ECM memory after performing the tests. Refer to EC-SR-56.
©GO TO 18.
17 CHECK INTERMITTENT INCIDENT
Perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-SR-114.
©INSPECTION END
SEF174P
DTC P0300 - P0304 NO.4-1CYLINDER MISFIRE,
MULTIPLE CYLINDER MISFIRESR20DE
Component Inspection
EC-229
Page 1030 of 2267

Component DescriptionNCEC0206The knock sensor is attached to the cylinder block. It senses
engine knocking using a piezoelectric element. A knocking vibration
from the cylinder block is sensed as vibrational pressure. This
pressure is converted into a voltage signal and sent to the ECM.
Freeze frame data will not be stored in the ECM for the knock
sensor. The MI will not light for knock sensor malfunction. The
knock sensor has one trip detection logic.
ECM Terminals and Reference ValueNCEC0207Specification data are reference values and are measured between each terminal and 48 (ECM ground).
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
81 W Knock sensor[Engine is running]
IIdle speed2.0 - 3.0V
On Board Diagnosis LogicNCEC0208
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0325
0325IAn excessively low or high voltage from the knock sen-
sor is sent to ECM.IHarness or connectors
(The knock sensor circuit is open or shorted.)
IKnock sensor
DTC Confirmation ProcedureNCEC0209NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
TESTING CONDITION:
Before performing the following procedure, confirm that bat-
tery voltage is more than 10V at idle.
With CONSULT-II
1) Turn ignition switch ªONº and select ªDATA MONITORº mode
with CONSULT-II.
2) Start engine and run it for at least 5 seconds at idle speed.
3) If DTC is detected, go to ªDiagnostic Procedureº, EC-SR-232.
With GST
Follow the procedure ªWith CONSULT-IIº above.
SEF598K
NEF068A
DTC P0325 KNOCK SENSOR (KS)SR20DE
Component Description
EC-230
Page 1031 of 2267
Wiring DiagramNCEC0210
YEC089A
DTC P0325 KNOCK SENSOR (KS)SR20DE
Wiring Diagram
EC-231
Page 1032 of 2267
Diagnostic ProcedureNCEC0211
1 RETIGHTEN GROUND SCREWS
Loosen and retighten engine ground screws.
SEF202X
©GO TO 2.
2 CHECK INPUT SIGNAL CIRCUIT-1
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector and knock sensor harness connector.
SEF210X3. Check harness continuity between knock sensor signal terminal 2 and ECM terminal 81.
Refer to wiring diagram.
Continuity should exist.
4. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 4.
NG©GO TO 3.
3 DETECT MALFUNCTIONING PART
Check the harness for open or short between knock sensor and ECM.
©Repair open circuit or short to ground or short to power in harness or connectors.
4 CHECK KNOCK SENSOR
Knock sensor
Refer to ªComponent Inspectionº, EC-SR-233.
OK or NG
OK©GO TO 5.
NG©Replace knock sensor.
Intake manifold collector
Engine ground
Knock sensor Knock sensor harness connector
Drive shaft View from under the vehicle
DTC P0325 KNOCK SENSOR (KS)SR20DE
Diagnostic Procedure
EC-232