P0307

P0307-CYLINDER 7 MISFIRE

Special Tools:

For a complete wiring diagram, refer to the Wiring Information.

- When Monitored:
Any time the engine is running, and the adaptive numerator has been successfully updated.

- Set Condition:
The threshold to set the fault is application specific; it is tied to the level of misfire that will cause emissions to increase to 1.5 times the standard or in some cases 1%. It is always a two trip fault above the calibrated RPM. It takes 1 fail to set a Pending Fault and two trips to set the MIL. Three good trips to turn off the MIL.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DIAGNOSTIC TROUBLE CODE (DTC)
1. Diagnose and repair any other active component or circuit DTCs before continuing with this procedure.
2. Turn the ignition on.
3. Using the scan tool, select View DTCs. Copy DTC and Freeze Frame information.
4. Start the engine and allow it to reach operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

NOTE: Attempt to operate the vehicle under conditions similar to which the DTC was set.

NOTE: It may be necessary to test drive the vehicle within the DTC monitoring conditions in order for this DTC to set.

5. With a scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. VISUAL INSPECTION

NOTE: Anything that affects the speed of the crankshaft can cause a misfire DTC.

NOTE: When a Misfire is detected for a particular cylinder, the PCM will shut down that cylinder's Injector Control circuit.

Visually inspect the engine for any of the following conditions:

- Worn serpentine belt
- Binding Engine-Driven accessories: A/C Compressor, P/S Pump, Water pump.
- Misalignment of the Water pump, P/S Pump and A/C Compressor pulleys
- Corroded PCM power and ground circuits.
- Misalignment of the Water pump, P/S Pump and A/C Compressor pulleys
- Corroded PCM power and ground circuits.
- Improper CKP, CMP, MAP, and TP Sensor mounting
- Poor connector/terminal to component connection for CKP sensor, CMP sensor, MAP sensor, TP sensor, fuel injector, ignition coil, etc.
- Vacuum leaks
- Restricted Air Induction system or Exhaust system.
- Internal engine component failures.

Were any of the above conditions present?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. (F342) ASD CONTROL OUTPUT CIRCUIT

1. Turn the ignition off.
2. Disconnect the No.7 Ignition Coil harness connector.
3. Disconnect the No.7 Fuel Injector harness connector.

NOTE: 4.7L injector shown, 5.7L similar.

4. Ignition on, engine not running.
5. Using a 12-volt test light connected to ground, probe the (F342) ASD Control Output circuit in the Ignition Coil harness connector and Fuel Injector harness connector before the actuation.

NOTE: Make sure the test light is probing the circuit before actuating the Relay or a DTC may set and not allow the actuation.

6. Using the scan tool, actuate the ASD.

Does the test light illuminate brightly?

Yes

- Go To 4

No

- Repair the excessive resistance or short to ground in the (F342) ASD Control Output circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. IGNITION SYSTEM OPERATION

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

1. Turn the ignition off.
2. Connect the Ignition Coil No.7 harness connector.
3. Remove the Ignition Coil.
4. Leave the Fuel Injector harness connector of the cylinder being tested disconnected.
5. Install a spark tester on the Ignition Coil.
6. While cranking the engine observe the spark coming from the spark tester.
7. Perform the same test on the ignition wire side of the Ignition coil.

NOTE: A crisp blue spark that is able to jump the gap of the spark tester should be generated at the coil on plug and at the end of the ignition wire.

Is good spark present?

Yes

- Go To 5

No

- Go To 14
NOTE: Connect the Fuel Injector harness connector before continuing.

5. SPARK PLUG

CAUTION: The 4.7L engine uses TWO DIFFERENT types of spark plugs. A total of 16 plugs are used. The plugs are mounted in two rows (banks). The upper row is used on the intake valve side of the cylinder head. The lower row is used on the exhaust valve side of the cylinder head. The upper row uses Nickel Yttrium plugs. The lower row uses Iridium plugs. DO NOT INTERCHANGE THESE PLUGS.

1. Turn the ignition off.
2. Remove the Spark Plug(s).
3. Inspect the Spark Plug(s) for the following conditions:
- Cracks
- Carbon Tracking
- Foreign Material
- Gap size out of specifications
- Loose or broken electrode

NOTE: Lightly tap the bottom of the spark plug on a solid surface. The electrode in the spark plug should not move.

Were any of the above conditions present?

Yes

- Replace the Spark Plug. Spark Plug - Removal
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 6

6. FUEL PRESSURE CHECK

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

1. Install Fuel Pressure Decay Tester to the fuel rail.
2. Start the engine and observe the fuel pressure reading.

NOTE: Fuel pressure specification is 407 kPa +/- 34 kPa (59 psi +/- 5 psi).

Choose a conclusion that best matches your fuel pressure reading.

Within Specification

- Go To 7

Below Specification

- Go To 12

Above Specification

- Replace the fuel filter/pressure regulator.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

7. FUEL PRESSURE LEAK DOWN

NOTE: Before continuing visually and physically inspect the fuel delivery system for external leaks or damage. Repair/replace as necessary.

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

1. Turn the ignition off.
2. Install the Fuel Pressure Decay Tester.
3. Start the engine and allow the fuel system to reach maximum pressure.
4. Turn the ignition off.

NOTE: Fuel specification is 407 kPa +/- 34 kPa (59 psi +/- 5 psi).

5. Close the Fuel System Isolation Valve and then wait five minutes before proceeding.
6. Read the Fuel Inlet and Fuel Outlet Pressure Gauges. The pressure should not drop more than 10 psi on either gauge.
7. Monitor the fuel pressure gauge for a minimum of five minutes.

NOTE: The pressure should not decrease by greater than 69 kPa (10 psi).

Does the pressure fall below the listed specification?

Yes - On Fuel Outlet Gauge

- Replace the leaking fuel injector(s).
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

Yes - On Fuel Outlet Gauge

- Replace the leaking fuel injector(s).
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 8

8. FUEL INJECTOR OPERATION

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

CAUTION: After each Fuel Injector actuation, start the engine to clean the cylinder of fuel. Failure to do so could cause engine damage.

1. Open the Fuel System Isolation Valve
2. Start the engine and allow the fuel pressure to reach maximum pressure.
3. Turn the ignition off.
4. Ignition on, engine not running.
5. Using the scan tool, actuate the No.7 Fuel Injector.
6. Monitor the fuel pressure gauge.

Does the fuel pressure gauge indicate a drop in fuel pressure?

Yes

- Go To 9

No

- Go To 10
NOTE: Turn the ignition off, remove the Fuel Pressure gauge, and connect the fuel lines before continuing.

9. ENGINE MECHANICAL
Check for any of the following conditions/mechanical problems:

- ENGINE VACUUM - must be at least 13 inches in neutral
- ENGINE VALVE TIMING - must be within specifications
- ENGINE COMPRESSION - must be within specifications
- ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
- ENGINE PCV SYSTEM - must flow freely
- TORQUE CONVERTER STALL SPEED - must be within specifications
- POWER BRAKE BOOSTER - no internal vacuum leaks
- FUEL - must be free of contamination
- CAM LOBES - must not be worn excessively
- CYLINDER LEAKAGE TEST - must be within specifications
- VALVE SPRINGS - cannot be weak or broken

Are there any engine mechanical problems?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 17

10. FUEL INJECTOR
1. Turn the ignition off.
2. Disconnect the No.7 Fuel Injector harness connector.
3. Ignition on, engine not running.

NOTE: When a Misfire is detected for a particular cylinder, the PCM will shut down that cylinder's Injector Control circuit.

4. Using the scan tool, erase DTCs.
5. Install an Injector Noid light.
6. Using the scan tool, actuate the Fuel Injector.

Does the Noid light blink/flicker during the actuation?

Yes

- Verify that there is good pin to terminal contact in the Fuel Injector and the Powertrain Control Module connectors. If OK, replace the Fuel Injector.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 11

11. (K26) INJECTOR CONTROL NO.7 CIRCUIT

1. Turn the ignition off.
2. Disconnect the C1 PCM harness connector.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the PCM Pinout Box (8815A) to perform diagnosis.

NOTE: 4.7L injector shown, 5.7L similar.

3. Check the (K26) Injector Control No.7 circuit for an open, short to ground, and short to voltage.

Was a problem found with the (K26) Injector Control No.7 circuit?

Yes

- Repair the excessive resistance or short in the (K26) Injector Control No.7 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 17

12. FUEL SUPPLY LINE RESTRICTED

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

1. Turn the ignition off.
2. Raise vehicle on hoist, and disconnect the fuel pressure line at the fuel pump module.
3. Install Fuel Pressure Decay Tester between the fuel supply line and the fuel pump module.
4. Ignition on, engine not running.
5. Using the scan tool, actuate the ASD Fuel System test and observe the fuel pressure gauge.

NOTE: Fuel pressure specification is 407 kPa +/- 34 kPa (59 psi +/- 5 psi).

Is the fuel pressure within specification?

Yes

- Repair or replace fuel supply line as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 13

13. FUEL PUMP INLET STRAINER

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

1. Turn the ignition off.
2. Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer.

Is the Fuel Inlet Strainer plugged?

Yes

- Replace the Fuel Pump Inlet Strainer.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Before continuing, check the Fuel Pump Module harness connector terminals for corrosion, damage, or terminal push out. Make sure the ground circuit is functional. Repair as necessary. Replace the Fuel Pump Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

14. IGNITION WIRE

NOTE: If the vehicle being tested does not have an ignition wire answer YES to this test and continue.

1. Turn the ignition off.
2. Remove the ignition wire.
3. Measure the resistance of the ignition wire.

Is the resistance below 10K Ohms?

Yes

- Go To 15

No

- Replace the Ignition Wire.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

15. IGNITION COIL

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

1. Disconnect the No.7 Ignition Coil harness connector.
2. Using a 12-volt test light connected to 12-volts, probe the (K97) Coil Control No.7 circuit.
3. Crank the engine for 5 seconds while observing the test light.

NOTE: The primary resistance of the 4.7L Ignition coil is 0.6 to 0.9 of an Ohm and the resistance of a 5.7L Ignition coil is 0.558 to 0.682 of an Ohm at 25° C (77° F).

Does the test light brightly blink/flicker?

Yes

- Verify that there is good pin to terminal contact in the Ignition Coil and the Powertrain Control Module connectors. If OK, replace the Ignition Coil.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 16

16. (K97) COIL CONTROL NO.7 CIRCUIT