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Home >> Suzuki >> 2012 >> Equator Base >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine General Information & Diagnosis - Qr25DE (3 Of 5) >> DTC P0300, P0301, P0302, P0303, P0304: Misfire >> Diagnosis Procedure

Diagnosis Procedure

DIAGNOSIS PROCEDURE CHART

Step Action YES NO
1  CHECK FOR INTAKE AIR LEAK AND PCV HOSE 
  1. Start engine and run it at idle speed.
  2. Listen for the sound of the intake air leak.
  3. Check PCV hose connection.

OK or NG 		 GO TO 2. 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 		 GO TO 3. Repair or replace it.
3  PERFORM POWER BALANCE TEST 
  1. With SDT 
    1. Perform "POWER BALANCE" in "Active test" mode.
    2. Is there any cylinder which does not produce a momentary engine speed drop?
  2. Without SDT 

    When disconnecting each fuel injector harness connector one at a time, is there any cylinder which does not produce a momentary engine speed drop?

G00538113Courtesy of SUZUKI OF AMERICA CORP.

Yes or No 		 GO TO 4. GO TO 9.
4  CHECK FUNCTION OF FUEL INJECTOR 
Does each fuel injector make an operating sound at idle?
G00538114Courtesy of SUZUKI OF AMERICA CORP.

Yes or No 		 GO TO 5. Check fuel injector(s) and circuit (s).
5  CHECK FUNCTION OF IGNITION COIL-I 
  1. Turn ignition switch OFF.
  2. Remove fuel pump fuse in IPDM E/R to release fuel pressure.
G06444145G06444146Courtesy of SUZUKI OF AMERICA CORP.SUZUKI OF AMERICA CORP.
NOTE: Do not use SDT to release fuel pressure, or fuel pressure applies again during the following procedure.

  1. 3. Start engine.
  2. 4. After engine stalls, crank it two or three times to release all fuel pressure.
  3. 5. Turn ignition switch OFF.
  4. 6. Remove all ignition coil harness connectors to avoid the electrical discharge from the ignition coils.
  5. 7. Remove ignition coil and spark plug of the cylinder to be checked.
  6. 8. Crank engine for 5 seconds or more to remove combustion gas in the cylinder.
  7. 9. Connect spark plug and harness connector to ignition coil.
  8. 10. Fix ignition coil using a rope etc. with gap of 13 - 17 mm between the edge of the spark plug and grounded metal portion as shown in the figure.
G06444145G06444146Courtesy of SUZUKI OF AMERICA CORP.SUZUKI OF AMERICA CORP.

  1. 11. Crank engine for about three seconds, and check whether spark is generated between the spark plug and the grounded metal portion.

    Spark should be generated. 

    CAUTION:
    • Never place the spark plug and the ignition coil within 50 cm (19.7 in) each other. Be careful not to get an electrical shock while checking, because the electrical discharge voltage becomes 20 kV or more.
    • It might damage the ignition coil if the gap of more than 17 mm is made.
    NOTE: When the gap is less than 13 mm, a spark might be generated even if the coil is malfunctioning.

OK or NG 		 GO TO 9. GO TO 6.
6  CHECK FUNCTION OF IGNITION COIL-II 
  1. Turn ignition switch OFF.
  2. Disconnect spark plug and connect a non-malfunctioning spark plug.
  3. Crank engine for about 3 seconds, and recheck whether spark is generated between the spark plug and the grounded metal portion.

    Spark should be generated. 


OK or NG 		 GO TO 7. Check ignition coil, power transistor and their circuits.
7  CHECK SPARK PLUG 
Check the initial spark plug for fouling, etc. Refer to [IGNITION COIL: REMOVAL AND INSTALLATION ].
G00538115Courtesy of SUZUKI OF AMERICA CORP.

OK or NG 		 Replace spark plug(s) with standard type one(s). Refer to IGNITION COIL: REMOVAL AND INSTALLATION .
  1. Repair or clean spark plug.
  2. GO TO 8.
8  CHECK FUNCTION OF IGNITION COIL-III 
  1. Reconnect the initial spark plugs.
  2. Crank engine for about 3 seconds, and recheck whether spark is generated between the spark plug and the grounded portion.

    Spark should be generated. 


OK or NG 		 INSPECTION END  Replace spark plug(s) with standard type one(s). For spark plug type. Refer to IGNITION COIL: REMOVAL AND INSTALLATION .
9  CHECK COMPRESSION PRESSURE 
Check compression pressure.
Refer to [COMPRESSION PRESSURE ]
OK or NG 		 GO TO 10. Check pistons, piston rings, valves, valve seats and cylinder head gaskets.
10  CHECK FUEL PRESSURE 
  1. Install all removed parts.
  2. Release fuel pressure to zero. Refer to [FUEL PRESSURE CHECK: QR25DE ]
  3. Install fuel pressure gauge kit [SST (J-44321)] and check fuel pressure. Refer to [FUEL PRESSURE CHECK: QR25DE ]

    At idle: Approximately 350 kPa (3.57 kg/cm 2  , 51 psi) 


OK or NG 		 GO TO 12. GO TO 11.
11  DETECT MALFUNCTIONING PART 
Check the following.
 Repair or replace.  
12  CHECK IGNITION TIMING 
Check the following items. Refer to [BASIC INSPECTION ].
G00538116Courtesy of SUZUKI OF AMERICA CORP.

OK or NG 		 GO TO 13. Follow the [BASIC INSPECTION ].
13  CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT 
  1. Turn ignition switch OFF.
  2. Disconnect ECM harness connector and A/F sensor 1 harness connector.
G06444147G06444148Courtesy of SUZUKI OF AMERICA CORP.SUZUKI OF AMERICA CORP.

  1. 3. Check harness continuity between the following terminals. Refer to WIRING DIAGRAM .
G06444147G06444148Courtesy of SUZUKI OF AMERICA CORP.SUZUKI OF AMERICA CORP.

Continuity should exist. 
  1. 4. Check harness continuity between ECM terminals 16, 35, 56, 75 or A/F sensor 1 terminals 1, 2, 5, 6 and ground. Refer to WIRING DIAGRAM .

    Continuity should not exist. 

  2. 5. Also check harness for short to power.

OK or NG 		 GO TO 14. Repair open circuit, short to ground or short to power in harness or connectors.
14  CHECK A/F SENSOR 1 HEATER 
Refer to [P0031, P0032 A/F SENSOR 1 HEATER ].
OK or NG 		 GO TO 15. Replace A/F sensor 1. Refer to [EXHAUST MANIFOLD AND THREE WAY CATALYST: EXPLODED VIEW [QR25DE] ].
15  CHECK MASS AIR FLOW SENSOR 
  1. With SDT 

    Check "MASS AIR FLOW" in "Data list" mode with SDT.

    At idling: 1.0 - 4.0 g/sec 

    At 2, 500 RPM: 4.0 - 12.0 g/sec 

  2. With GST 

    Check mass air flow sensor signal in SERVICE $01 with GST.

    At idling: 1.0 - 4.0 g/sec 

    At 2, 500 RPM: 4.0 - 12.0 g/sec 


OK or NG 		 GO TO 16. Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or grounds. Refer to P0101 MAF SENSOR .
16  CHECK SYMPTOM MATRIX CHART 
Check items on the rough idle symptom in [ENGINE CONTROL SYSTEM SYMPTOMS: SYMPTOM MATRIX CHART ]
OK or NG 		 GO TO 17. Repair or replace.
17  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 [DTC INDEX: ECM ].		 GO TO 18.  
18  CHECK INTERMITTENT INCIDENT 
Perform [SERVICE INFORMATION FOR ELECTRICAL INCIDENT: INTERMITTENT INCIDENT ]		 INSPECTION END 
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