Sfi System - P0303

1. Description

2. Wiring diagram

3. Confirmation driving pattern

4. Inspection procedure

5. Check any other dtcs output (in addition to misfire dtcs)

6. Read value using intelligent tester (misfire rpm and misfire load)

7. Check pcv hose connections

8. Check misfire count (cylinder #1, #2, #3 and #4)

9. Perform active test using intelligent tester (fuel cut #1 to #4)

10. Check spark plug

11. Check for sparks and ignition

12. Check cylinder compression pressure of misfiring cylinder

13. Change normal spark plug and check spark of misfiring cylinder

14. Inspect ecm terminal of misfiring cylinder (#10, #20, #30, and/or #40 voltage)

15. Check harness and connector (injector - ecm)

16. Check fuel injector of misfiring cylinder

17. Check valve clearance of misfiring cylinder

18. Check air induction system

19. Check valve timing

20. Check fuel pressure

21. Read value using intelligent tester (coolant temp)

22. Read value using intelligent tester (maf)

DTC P0300 Random / Multiple Cylinder Misfire Detected

DTC P0301 Cylinder 1 Misfire Detected

DTC P0302 Cylinder 2 Misfire Detected

DTC P0303 Cylinder 3 Misfire Detected

DTC P0304 Cylinder 4 Misfire Detected

​

DESCRIPTION

WIRING DIAGRAM

CONFIRMATION DRIVING PATTERN

1. Connect an intelligent tester to the DLC3.
   
2. Turn the ignition switch to ON and turn the tester on.
   
3. Record the DTC(s) and freeze frame data.
   
4. Switch the ECM from normal mode to check mode (Click here).
   
5. Read the misfire counts of each cylinder (CYL #1 to #4) with the engine in an idling condition. If any misfire count is displayed, skip the following confirmation driving pattern.
   
6. Drive the vehicle several times with the conditions, such as engine rpm and engine load, shown in Misfire RPM and Misfire Load in the Data List.
   
   

   HINT:

   In order to store misfire DTCs, it is necessary to drive the vehicle for the period of time shown in the table below, with the MISFIRE RPM and MISFIRE Load in the Data List.

   
   

   Engine RPM	Duration
   Idling	5.75 minutes or more
   1,000	4 minutes or more
   2,000	2.5 minutes or more
   3,000	1.5 minute or more

7. Check whether misfires have occurred by checking DTCs and freeze frame data.
   

   HINT:

   Do not turn the ignition switch off until the stored DTC(s) and freeze frame data have been recorded. When the ECM returns to normal mode (default), the stored DTC(s), freeze frame data and other data will be erased.

8. Record the DTC(s), freeze frame data and misfire counts.
   
9. Turn the ignition switch off and wait for at least 5 seconds.
   

INSPECTION PROCEDURE

HINT:

1. If any DTCs other than misfire DTCs are output, troubleshoot those DTCs first.
   
2. Read freeze frame data using an intelligent tester. Freeze frame data record the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data, from the time the malfunction occurred.
   
3. If the misfire does not recur when the vehicle is brought to the workshop, reproduce the conditions stored in the freeze frame data.
   
4. If the misfire still cannot be reproduced even though the conditions stored in the freeze frame data have been duplicated, one of the following factors is considered to be a possible cause of the problem:
   
5. 1. The fuel level is low.
      
   2. Improper fuel is used.
      
   3. The spark plugs are dirty.
      
   4. The problem is complex due to multiple factors.
      
6. After finishing repairs, check that no misfire occur in each cylinder (Cylinder #1, #2, #3 and #4).
   
7. Be sure to confirm that no misfiring cylinder DTCs are set again by conducting the confirmation driving pattern, after the repairs.
   
8. For 6 and 8 cylinder engines, the ECM intentionally does not set the specific misfiring cylinder DTCs at high engine RPM. If misfires only occur during high engine RPM driving, only DTC P0300 is set.
   In the event of DTC P0300 being present, perform the following operations:
   
9. 1. Clear the DTC (Click here).
      
   2. Start the engine and conduct the confirmation driving pattern.
      
   3. Read the misfiring rates of each cylinder or DTC(s) using the tester.
      
   4. Repair the cylinder(s) that has a high misfiring rate or is indicated by the DTC.
      
   5. After finishing repairs, conduct the confirmation driving pattern again, in order to verify that DTC P0300 is not set.
      
10. When either Short FT #1 or Long FT #1 in the freeze frame data is outside the range of +-20 %, the air-fuel ratio may be rich (-20 % or less) or lean (+20 % or more).
    
11. When the Coolant Temp in the freeze frame data is less than 75°C (167°F), the misfires occurred only while warming up the engine.
    

1. Connect an intelligent tester to the DLC3.

2. Turn the ignition switch to ON and turn the tester on.

3. Select the following menu items: Powertrain / Engine and ECT / DTC.

4. Read DTCs.

   Result:

   Display (DTC Output)	Proceed To
   P0300, P0301, P0302, P0303 and/or P0304	A
   P0300, P0301, P0302, P0303 and/or P0304 and other DTCs	B

HINT:

If any DTCs other than P0300, P0301, P0302, P0303 and P0304 are output, troubleshoot those DTCs first.

B	GO TO DTC CHART

A

1. Connect an intelligent tester to the DLC3.

2. Turn the ignition switch to ON and turn the tester on.

3. Select the following menu items: Powertrain / Engine and ECT / Data List / Misfire RPM and Misfire Load.

4. Read and note the Misfire RPM and Misfire Load (engine load) values.

   HINT:

   The Misfire RPM and Misfire Load indicate the vehicle conditions under which the misfire occurred.

NEXT

OK:

PCV hose is connected correctly and is not damaged.

NG	REPAIR OR REPLACE PCV HOSE

OK

1. (a) Connect an intelligent tester to the DLC3.
   
2. (b) Turn the ignition switch to ON and turn the tester on.
   
3. (c) Clear DTCs (Click here).
   
4. (d) Select the following menu items: Powertrain / Engine and ECT / Data List / Cylinder #1 to #4 Misfire Rate.
   
5. (e) Allow the engine to idle.
   
6. (f) Read each value for Cylinder #1 to #4 Misfire Rate displayed on the tester. If no misfire counts occur in any cylinders, perform the following conditions:
   
7. 1. (1) Shift the gear selector lever to the D position.
      
   2. (2) Check the Cylinder #1 to #4 Misfire Rate.
      
   3. (3) If misfire counts are still not displayed, perform steps (g) and (h) and then check the misfire counts again.
      
8. (g) Drive the vehicle with the Misfire RPM and Misfire Load noted in step 2.
   
9. (h) Read the Cylinder #1 to #4 Misfire Rate or DTCs displayed on the tester.
   

Result:

Misfire Count	Proceed To
Most misfire occur in only one or two cylinders	A
Three cylinders or more have equal misfire counts	B

HINT:

1. If it is difficult to reproduce misfires for each cylinder, check the Data List item called Misfire Margin. Try to find vehicle driving conditions that lower the Misfire Margin value. Values above 30 % are considered normal.
   
2. If the freeze frame data's record of the ECT is below 75°C (167°F), the misfire may be detected only when the engine is cold.
   
3. If the freeze frame data's record of the Engine Run Time is below 120 seconds, the misfire may be detected immediately after the engine is started.
   

B	Go to step 14

A

1. Allow the engine to idle.

2. Select the following menu items: Powertrain / Engine and ECT / Active Test / Control the Cylinder #1 to #4 Fuel Cut.

3. If a cylinder has a high misfire count, cut fuel to the cylinder. Compare the misfire count of the cylinder before fuel cut and after fuel cut.

   Result:

   Misfire Count in Each Cylinder	Proceed To
   Misfire count of cylinder before fuel cut and after fuel cut roughly same	A
   Misfire count of cylinder before fuel cut lower than after fuel cut	B

   NOTICE:

   This Active Test cannot be performed while the vehicle is being driven.

   HINT:

   If the misfire count of the cylinder before and after the fuel cut are roughly the same, the cylinder is misfiring.

   If the misfire count of the cylinder before the fuel cut is lower than after the fuel cut, the cylinder misfires sometimes.

B	Go to step 11

A

1. Remove the ignition coil and the spark plug of the misfiring cylinder.

2. Measure the spark plug electrode gap.

   Standard:

   0.7 to 0.8 mm (0.028 to 0.032 in.)
   

3. Check the electrode for carbon deposits.

   Recommended spark plug:

   Manufactures	Products
   DENSO	K16R-U
   NGK	BKR5EYA

   NOTICE:

   If the electrode gap is larger than standard, replace the spark plug. Do not adjust the electrode gap.

4. Reinstall the ignition coil and the spark plug.

NG	REPLACE SPARK PLUG

OK

1. Disconnect the injector connectors, in order to prevent the engine from starting.

2. Install the spark plug onto the ignition coil.

3. Attach the spark plug assembly to the cylinder head.

4. Crank the engine for less than 2 seconds and check the spark.

   OK:

   Sparks jump across electrode gap.
   

5. Reconnect the injector connectors.

NG	Go to step 9

OK

1. Measure the cylinder compression pressure of the misfiring cylinder.

OK	Go to step 10

NG
CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

1. Change the installed spark plug to a spark plug that functions normally.

2. Perform a spark test.

   CAUTION:

   Always disconnect all injector connectors.

   NOTICE:

   Do not crank the engine for more than 2 seconds.

   1. Install the spark plug to the ignition coil and connect the ignition coil connector.

   2. Disconnect the injector connector.

   3. Ground the spark plug.

   4. Check if sparks occur while the engine is being cranked.

      OK:

      Sparks jump across electrode gap.
      

NG	REPLACE IGNITION COIL ASSEMBLY THEN CONFIRM THAT THERE IS NO MISFIRE

OK
REPLACE SPARK PLUG

1. Disconnect the C20 ECM connector.

2. Turn the ignition switch to ON.

3. Measure the voltage between the terminals of the ECM connector.

   Standard voltage:

   Tester Connections	Specified Conditions
   #10 (C20-108) - E01 (C20-45)	9 to 14 V
   #20 (C20-107) - E01 (C20-45)
   #30 (C20-106) - E01 (C20-45)
   #40 (C20-105) - E01 (C20-45)

4. Reconnect the ECM connector.

OK	Go to step 12

NG

1. Disconnect the injector connector (of the misfiring cylinder).

2. Disconnect the C20 ECM connector.

3. Turn the ignition switch to ON.

4. Measure the resistance and voltage between the injector and the ECM connector terminals.

   Standard voltage:

   Cylinder	Tester Connections	Specified Conditions
   No. 1	C4-1 - Body ground	9 to 14 V
   No. 2	C5-1 - Body ground
   No. 3	C6-1 - Body ground
   No. 4	C7-1 - Body ground

   Standard resistance:

   Cylinder	Tester Connections	Specified Conditions
   No. 1	C4-2 - Body ground	10 kΩ or higher
   	C4-2 - #10 (C20-108)	Below 1 Ω
   No. 2	C5-2 - Body ground	10 kΩ or higher
   	C5-2 - #20 (C20-107)	Below 1 Ω
   No. 3	C6-2 - Body ground	10 kΩ or higher
   	C6-2 - #30 (C20-106)	Below 1 Ω
   No. 4	C7-2 - Body ground	10 kΩ or higher
   	C7-2 - #40 (C20-105)	Below 1 Ω

5. Reconnect the injector connector.

6. Reconnect the ECM connector.

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

1. Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor).

NG	REPLACE FUEL INJECTOR ASSEMBLY (Click here)

OK

1. Check the valve clearance (Click here).

NG	ADJUST VALVE CLEARANCE

OK

1. Check the air induction system for vacuum leakage.

   OK:

   No leakage from air induction system.
   

NG	REPAIR OR REPLACE AIR INDUCTION SYSTEM

OK

1. Remove the cylinder head cover.

2. Turn the crankshaft pulley, and align its groove with the timing mark "0" on the timing chain cover.

3. Check that the timing marks on the camshaft timing sprocket and camshaft timing gear are facing upward as shown in the illustration.

   1. If not, turn the crankshaft 1 revolution (360°), then align the marks as above.
      

   OK:

   Timing marks on camshaft timing gears are aligned as shown in the illustration.
   

4. Reinstall the cylinder head cover.

NG	ADJUST VALVE TIMING

OK

1. Check the fuel pressure (Click here).

NG	CHECK AND REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE AND FILTER

OK

1. Connect the intelligent tester to the DLC3.

2. Turn the ignition switch to ON and turn the tester on.

3. Select the following menu items: Powertrain / Engine and ECT / Data List / Coolant Temp.

4. Read the Coolant Temp twice, when the engine is both cold and warmed up.

   Standard:

   With cold engine: Same as ambient air temperature.
   

   With warm engine: 75°C to 100°C (167°F to 212°F).
   

NG	REPLACE ENGINE COOLANT TEMPERATURE SENSOR

OK

1. Connect an intelligent tester to the DLC3.

2. Turn the ignition switch to ON and turn the tester on.

3. Select the following menu items: Powertrain / Engine and ECT / Data List / Coolant Temp and MAF.

4. Allow the engine to idle until the Coolant Temp reaches 75°C (167°F) or more.

5. Read the MAF with the engine in an idling condition and at an engine speed of 2,500 rpm.

   Standard:

   MAF while engine idling: 1 to 3 g/sec (shift position: N, A/C: OFF).
   

   MAF at engine speed of 2,500 rpm: 2 to 6 g/sec (shift position: N, A/C: OFF).
   

NG	REPLACE MASS AIR FLOW METER (Click here)

OK
CHECK FOR INTERMITTENT PROBLEMS (Click here)