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Misfire Detection Monitor

DTC P0300, P0301, P302, P0303, P0304, P0305, P0306 DETECTION CONDITION AND POSSIBLE CAUSES

DTC P0300, P0301, P302, P0303, P0304, P0305, P0306 MISFIRE DETECTION MONITOR
DETECTION CONDITION 
  • DTC P0300 indicates multiple cylinders are misfiring or the PCM cannot identify which cylinder is misfiring.
  • DTC P0301 through P0306 indicates random misfire detected or cylinder 1, 2, 3, 4, 5, or 6 misfire detected.
POSSIBLE CAUSE 
  • Ignition system.
  • Fuel injectors.
  • Fuel pressure.
  • Evaporative Emission system.
  • Base engine.
  • Running out of fuel.
  • Camshaft Position (CMP) sensor.
  • Stuck open EGR Valve.
DTC P0300, P0301, P302, P0303, P0304, P0305, P0306 INSPECTION

STEP INSPECTION ACTION
1 CHECK POSSIBLE CAUSES OF MISFIRE
NOTE: Running out of fuel can turn on the MIL and possibly store a Continuous Misfire DTC.
  • Misfire Continuous Memory DTCs:
    • P0301-Cyl. No.1, Fuel Inj. test pin 75
    • P0302-Cyl. No.2, Fuel Inj. test pin 101
    • P0303-Cyl. No.3, Fuel Inj. test pin 74
    • P0304-Cyl. No.4, Fuel Inj. test pin 100
    • P0305-Cyl. No.5, Fuel Inj. test pin 73
    • P0306-Cyl. No.6, Fuel Inj. test pin 99
  • Has the vehicle recently run out of fuel? 
 Yes OBD II system OK.
Go to step 26.
No Go to step 2.
2 CHECK DAMPER AND PULLEY ASSEMBLY
NOTE: This step is for engines with damper-mounted pulse rings.
CAUTION: Remove the front cover if necessary to observe the crankshaft pulley.
  • Observe the crankshaft pulley for wobble.
  • Examine the pulse ring fastened to the harmonic damper.
  • Does the crankshaft pulley wobble or is the pulse ring loose or damaged? 
 Yes Disconnect battery for 5 minutes to allow PCM to learn new data, due to the old pulse ring. Replace the pulley or damper assembly. Complete Misfire Monitor Repair Verification Drive Cycle.
See DRIVE CYCLES  .
Go to step 26.
No Go to step 3.
3 CHECK FOR ADAPTIVE FUEL MONITOR AND HO2S CONTINUOUS MEMORY DTCS?
NOTE: The following is a list of non-misfire DTCs to look for in Continuous Memory.
  • P0136, P0171, P0172, P0175, P1130, P1150
  • Are any of the DTCs listed above present? 
 Yes Go to step 5.
No Go to step 4.
4 CHECK FOR OTHER NON-MISFIRE CONTINUOUS MEMORY DTCS
  • Check for other non-misfire Continuous Memory DTCs which could cause the misfire DTC.
  • Are other non-misfire Continuous Memory DTCs present? 
 Yes Disregard Misfire DTC at this time.
See DIAGNOSTIC TROUBLE CODE NUMBERS  and address the next Continuous Memory DTC.
No Go to step 5.
5 CHECK FOR ON-DEMAND SELF-TEST DTCS
  • Check for any Key On Engine Off (KOEO) DTCs which could cause the Misfire DTC.
  • Are any Key On Engine Off (KOEO) DTCs displayed on the NGS Tester? 
 Yes Go to appropriate pinpoint test.
See DIAGNOSTIC TROUBLE CODE NUMBERS  and proceed as required.
No See TEST 17: IGNITION SCOPE TEST  to evaluate spark plugs and secondary wires.
If OK, Go to step 6.
6 CHECK FOR OTHER KEY ON ENGINE RUNNING (KOER) DTCS
  • Check for any Key On Engine Running (KOER) DTCs which could cause the Misfire DTC.
  • Are any Key On Engine Running (KOER) DTCs displayed on the NGS Tester? 
 Yes If DTCs P1132, P1138, P1152, P1131, P1137 or P1151 are present:
Go to step 8.
All others:
Go to appropriate DTC chart
See DIAGNOSTIC TROUBLE CODE NUMBERS  and proceed as required.
No Go to step 7.
7 CHECK/COMPARE PID VALUES
  • Connect NGS Tester.
  • Accessories off (A/C, heater, etc.).
  • Start engine and warm to operating temperature.
  • Access DPFEGR PID with the NGS Tester.
  • Key On Engine Off (KOEO).
  • Record DPFEGR PID value.
  • Start engine, let idle.
  • Compare Key On Engine Off (KOEO) and engine running PID values.
  • Key OFF.
  • Was engine running PID value within 0.15 volt of Key On Engine Off (KOEO) value? 
 Yes Go to step 8.
No See DPFE SENSOR MALFUNCTION  .
8 CHECK INJECTOR DRIVER PIDS INJ1F THROUGH INJ6F
  • Key On Engine Off (KOEO).
  • Access appropriate PID(s) for the suspect fuel injector.
  • Is the PID status Yes? 
 Yes Go to step 9.
No Go to step 10.
9 CHECK RESISTANCE OF FUEL INJECTOR(S) AND HARNESS
  • Disconnect PCM.
  • Install Breakout Box.
  • Measure resistance between suspect fuel injector test pin and test pin 71 or 97 at the Breakout Box.
  • Is the resistance between 11.0 and 18.0 ohms? 
 Yes Replace PCM. See POWERTRAIN CONTROL MODULE .
Go to step 26.
No See ADAPTIVE FUEL CONTROL  .
Go to step 17.
10 CHECK FUEL PRESSURE
WARNING: The fuel system will remain pressurized when the engine is not running. To prevent injury or fire, use caution when working on the fuel system.
  • Install fuel pressure gauge.
  • Start engine and run at idle. Record fuel pressure.
  • Increase engine speed to 2,500 rpm and maintain for 1 minute. Note and compare fuel pressure.
  • Key OFF.
  • Was fuel pressure between 386-496 kPa (56-72 psi) 3.0L flex fuel 380-517 kPa (55-75 psi)? 
 Yes Go to step 11.
No See TEST 5: FUEL DELIVERY SYSTEM  .
11 CHECK ABILITY OF FUEL SYSTEM TO HOLD FUEL PRESSURE
  • Start and run engine at idle. Note fuel pressure.
  • Increase engine speed to 2,500 rpm and hold for 1 minute.
  • Look for fuel leaking at the fuel injector O-ring, fuel pressure regulator and the fuel lines to the fuel charging assembly.
  • Turn engine off.
  • Did fuel pressure remain at specification within 16.5 kPa (5 psi) for 60 seconds? 
 Yes Go to step 12.
No See FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article to determine which area within the fuel delivery system is at fault.
12 CHECK FUEL INJECTOR FOR FLOW AND LEAKAGE
  • Verify that the flow rate for each fuel injector is within specification using an injector flow tester.
  • Is flow rate for each fuel injector within specification? 
 Yes Fuel delivery system is not likely to have caused the Misfire DTC.
Go to step 13 to diagnose vacuum system.
No Replace or clean the inoperative fuel injector(s) as necessary.
Go to step 26.
13 CHECK VACUUM SYSTEM
NOTE: Some vacuum leaks can be heard.
  • Inspect all vacuum lines for damage, such as pinched lines, cracks, proper routing and assembly.
  • Is the vehicle vacuum system OK? 
 Yes Go to step 14.
No Repair the vacuum system.
Complete Misfire Monitor Repair Verification Drive Cycle.
See DRIVE CYCLES  .
Go to step 26.
14 CHECK EVAPORATIVE EMISSION SYSTEM
  • The Misfire Monitor can be influenced by the Evaporative Emission (EVAP) System. The next four test steps will diagnose the EVAP System.
  • Check the evaporative emissions canister for fuel saturation.
  • Is there an excess amount of liquid fuel present in the evaporative emissions canister? 
 Yes Replace evaporative emissions canister. Complete Misfire Monitor Repair Verification Drive Cycle.
See DRIVE CYCLES  .
Go to step 26.
No CHECK fuel tank vent system.
Go to step 15.
15 PRESSURE TEST EVAPORATIVE EMISSION SYSTEM
  • Pressure test EVAP Emission System.
  • Install EVAP System Tester 134-00056 or equivalent, first at the EVAP SERVICE port, if equipped, then at the fuel filler cap.
  • Follow test instructions from the Tester Kit.
  • Is EVAP system holding pressure? 
 Yes Go to step 16.
No Repair as necessary. Complete Misfire Monitor Repair Verification Drive Cycle.
See DRIVE CYCLES  .
Go to step 26.
16 CHECK VACUUM IN EVAPORATIVE EMISSION SYSTEM
  • Check for blockage/restrictions or cut hoses between engine vacuum port and EVAP canister.
  • Check for blockage in fuel tank vent system.
  • Is fault indicated? 
 Yes Replace damaged vacuum hoses or remove blockage/restrictions. Complete Misfire Monitor Repair Verification Drive Cycle.
See DRIVE CYCLES  .
Go to step 26.
No Go to step 18.
17 CHECK FOR BASE ENGINE CONCERNS
NOTE: This step will determine if there are any base engine concerns that may have caused the misfire DTC or drive concern.
  • Perform the following tests in order to evaluate base engine integrity.
    • Perform an Engine Compression test.
    • Perform Dynamic Valve Train analysis.
    • Check PCV system.
    • Check possible leakage points.

    See ENGINE COMPONENT TESTS  , for all of the above.

  • Is any service required? 
 Yes Service as necessary.
Go to step 26.
No The fault that caused the misfire DTC is an intermittent.
See TEST 4: INTERMITTENT  .
18 CHECK FOR EVAPORATIVE EMISSION PURGE VALVE HOUSING LEAKS
  • Connect EVAP purge valve.
  • Install a hand vacuum pump to the fuel vapor port to EVAP canister on the EVAP purge valve vacuum line.
  • Apply 53 kPa (16 in-Hg) of vacuum with the vacuum pump.
  • Does the EVAP purge valve hold vacuum at room temperature? 
 Yes Go to step 19.
No Remove vacuum pump. Replace EVAP purge valve.
Go to step 26.
19 CHECK FOR FILTER CONTAMINATION OR DAMAGE ON EVAPORATIVE EMISSION PURGE VALVE
  • Vacuum line from input port to intake manifold on EVAP purge valve (control vacuum solenoid part of the valve) is removed.
  • Install a hand held vacuum pump to the open input vacuum port on the EVAP purge valve.
  • Apply 48-52 kPa (10-15 in-Hg) of vacuum to the EVAP purge valve.
  • Does the EVAP purge valve hold vacuum or is the valve very slow to release vacuum to atmosphere? 
 Yes Complete Misfire Monitor Repair Verification Drive Cycle.
See DRIVE CYCLES  . Service EVAP purge valve filter.
If unable to clean filter or remove blockage, replace the EVAP purge valve.
Go to step 26.
No Remove vacuum pump.
Reconnect all components.
Go to step 17.
20 CHECK FOR ADDITIONAL MISFIRE DTCS
  • DTC P0300 indicates multiple cylinders are misfiring or PCM cannot identify which cylinder is misfiring.
  • Are any other misfire DTCs present? 
 Yes Return to step 1.
No GO to step 21.
21 CHECK FOR OTHER CONTINUOUS MEMORY DTCS
  • Are other Continuous Memory DTCs present? 
 Yes Refer to appropriate pinpoint test.
See DIAGNOSTIC TROUBLE CODE NUMBERS  .
No Go to step 22.
22 CHECK/COMPARE PID VALUES
  • Connect NGS Tester.
  • Accessories off (A/C, heater, radio, etc.).
  • Start engine and warm to operating temperature.
  • Access DPFEGR PID with the NGS Tester.
  • Key On Engine Off (KOEO).
  • Record DPFEGR PID value.
  • Start engine, let idle.
  • Compare Key On Engine Off (KOEO) and engine running PID values.
  • Key OFF.
  • Was engine running DPFEGR PID value within 0.15 volt of Key On Engine Off (KOEO) value? 
 Yes Disconnect NGS Tester.
For 2.5L and 4.0L engines:
Go to step 24.
For 3.0L engine:
Go to step 23.
No Go to step 25.
23 CHECK CMP SENSOR OUTPUT
  • DTC P1309 indicates Misfire Detection Monitor is not enabled.
  • Breakout Box installed, PCM disconnected.
  • Connect multimeter between test pin 85 (CMP) and test pins 51 or 103 (PWR GND) at the Breakout Box.
  • Bump engine in short bursts with the starter without starting engine for at least 10 engine revolutions.
  • Does multimeter reading switch between low (less than 2.0 volts DC) and High (greater than 8.0 volts DC)? 
 Yes
NOTE: A Hall effect type CMP sensor that is installed out of synchronization will produce a DTC.
Verify the correct installation. See IGNITION SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article.If installed properly, replace PCM. See POWERTRAIN CONTROL MODULE .Go to step 24.
No Replace CMP sensor.
Complete Misfire Monitor Repair Verification Drive Cycle.
See DRIVE CYCLES  .
Go to step 24.
24 CHECK CMP SENSOR OUTPUT
  • Breakout Box installed, PCM connected.
  • Set multimeter on AC scale (monitor less than 5.0 volts).
  • Measure voltage between test pin 85 (CID) and test pins 51, 103 (PWR GND) at the Breakout Box while running the engine at varying rpm.
  • Does AC voltage vary greater than 0.1 volt AC? 
 Yes Verify correct CMP sensor installation by referring to:
IGNITION SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article. .
If CMP is installed correctly, replace PCM. See POWERTRAIN CONTROL MODULE .
Go to step 26.
No Replace CMP sensor.
See IGNITION SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article .
Complete Misfire Monitor Repair Verification Drive Cycle.
See DRIVE CYCLES  .
Go to step 26.
25 CHECK OPERATION OF EGR VALVE
NOTE: Perform KOER Self Test and repair any DTCs before proceeding with this test.
  • The symptom charts have indicated possible EGR flow at idle with no EGR DTCs output. Possible causes:
    • EGR valve not fully seating.
    • EGR vacuum regulator solenoid vent restricted.
    • Damaged EGR vacuum regulator solenoid.
    • Disconnect vacuum hose at EGR valve and plug hose.
    • Key On Engine Off (KOEO).
    • Access DPFEGR PID with a NGS Tester and note voltage.
    • Start engine and bring to idle.
    • With engine at idle, look at the DPFEGR PID voltage and compare to the engine off reading. An increase in the voltage at idle indicates that the DPFE sensor is sensing EGR flow.
    • Key OFF.
  • Was the DPFEGR PID voltage greater at idle by a minimum of 0.15 volt than with the engine off? 
 Yes The DPFEGR PID voltage is indicating EGR flow at idle. Since the EGR vacuum hose is disconnected and plugged, the fault is most likely in the EGR valve.
Remove and inspect the EGR valve for signs of contamination, unusual wear, carbon deposits, binding and other damage.
Repair as necessary using a EGR Valve Cleaner.
Go to step 26.
No This indicates a fault in the EGR valve vacuum supply.
Inspect the EGR vacuum regulator solenoid vent and vent filter for restrictions.
Repair as necessary.
If OK, replace EGR vacuum regulator solenoid.
Go to step 26.
26


DTC P1309 DETECTION CONDITION AND POSSIBLE CAUSES

DTC P1309 MISFIRE DETECTION MONITOR
DETECTION CONDITION 
  • When the misfire monitor is disabled, usually due to the input signal generated by the camshaft position sensor (CMP), by sensing the passage of teeth from the CMP wheel.
POSSIBLE CAUSE 
  • Damaged CMP.
  • Damaged PCM.
  • ECT, MAF and CKP sensors
DTC P1309 INSPECTION

STEP INSPECTION ACTION
1 CHECK CMP SENSOR OUTPUT
  • Breakout Box installed, PCM disconnected.
  • Connect multimeter
  • Start engine and vary engine RPM.
  • Measure voltage between PCM test pin 85 (CMP) and test pins 51 or 103 (PWR GND) at the Breakout Box.
  • Does AC voltage vary greater than 0.1 volt AC? 
 Yes Verify the correct installation
See CAMSHAFT POSITION (CMP) SENSOR in REMOVAL, OVERHAUL & INSTALLATION article.
If CMP sensor is installed properly, replace PCM. See POWERTRAIN CONTROL MODULE .
Go to step 2.
No Replace CMP sensor.
See CAMSHAFT POSITION (CMP) SENSOR in REMOVAL, OVERHAUL & INSTALLATION article. .
Complete Misfire Monitor Verification Drive Cycle.
See DRIVE CYCLES 
Go to step 2.
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