DRIVEABILITY - GAS. All symptoms listed above are diagnosed using the same tests. The title for the tests will be P0300-MULTIPLE CYLINDER MIS-FIRE.

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Lenard Cole
5 years ago
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1 Symptom List: P0300-MULTIPLE CYLINDER MIS-FIRE P0301-CYLINDER #1 MISFIRE P0302-CYLINDER #2 MISFIRE P0303-CYLINDER #3 MISFIRE P0304-CYLINDER #4 MISFIRE P0305-CYLINDER #5 MISFIRE P0306-CYLINDER #6 MISFIRE Test Note: symptoms listed above are diagnosed using the same tests. The title for the tests will be P0300-MULTIPLE CYLINDER MIS-FIRE. When Monitored and Set Condition: P0300-MULTIPLE CYLINDER MIS-FIRE P0301-CYLINDER #1 MISFIRE P0302-CYLINDER #2 MISFIRE P0303-CYLINDER #3 MISFIRE 79

2 P0304-CYLINDER #4 MISFIRE P0305-CYLINDER #5 MISFIRE P0306-CYLINDER #6 MISFIRE INTERMITTENT MISFIRE VISUAL INSPECTION IGNITION WIRE (F42) ASD RELAY OUPUT CIRCUIT ENGINE MECHANICAL PROBLEM IGNITION COIL COIL CONTROL CIRCUIT SPARK PLUG CHECKING FUEL PRESSURE FUEL PUMP INLET STRAINER PLUGGED RESTRICTED FUEL SUPPLY LINE FUEL PUMP MODULE CHECKING FUEL LEAK DOWN FUEL INJECTOR INJECTOR CONTROL CIRCUIT PCM Possible Causes 80

3 1 NOTE: Check for any TSB s that apply to a Misfire condition. Review the vehicle repair history for any misfire condition repairs that have been performed. Read and record the FREEZE FRAME DATA. Select OBD II MONITORS. Read and record the MIS-FIRE SIMILAR CONDITIONS WINDOW DATA. With these screens, attempt to duplicate the condition(s) that has set this DTC. When the vehicle is operating in the SIMILAR CONDITIONS WINDOW, refer to the WHICH CYLINDER IS MISFIRING screen. Observe the WHICH CYLINDER IS MISFIRING screen for at least one minute. Is there a misfire present? Yes Go To 2 No Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). 2 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 cylinders 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 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. i.e., CKP sensor, Fuel Injector, Ign coil, etc. - Vacuum leaks - Restricted Air Induction system or Exhaust system. Were any of the above conditions present? Yes Repair as necessary. No Go To 3 3 Turn the ignition off. Disconnect the Ignition Coil harness connector. Disconnect the Fuel Injector harness connector. With the DRBIII, actuate the ASD Relay. Using a 12-volt test light connected to ground, probe the (F42) ASD Relay Output circuit at the Ignition Coil harness connector and Fuel Injector harness connector. Does the test light illuminate brightly? Yes Go To 4 No Repair the excessive resistance or short to ground in the (F42) ASD Relay Output circuit. 81

4 4 Turn the ignition off. Disconnect the Ignition wire from the spark plug. Disconnect the Fuel Injector harness connector of the cylinder being tested. NOTE: Before continuing inspect the ignition wire for damage or carbon tracking. Replace as necessary. Install a spark tester on the ignition wire. While cranking the engine observe the spark coming from the spark tester. NOTE: A crisp blue spark that is able to jump the gap of the spark tester should be generated. Is good spark present? Yes Go To 5 No Go To 14 5 Turn the ignition off. Remove the Spark Plug. Inspect the Spark Plug for the following conditions. - Cracks - Carbon Tracking - Foreign Material - Gap size out of specifications - Loose or broke 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 condition present? Yes Replace the Spark Plug. No Go To 6 6 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 Install a fuel pressure gauge. Start the engine and observe the fuel pressure reading. NOTE: Fuel pressure specification is 334 KPa +/- 34 KPa (49 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. 82

5 7 NOTE: Before continuing visually and physically inspect the fuel delivery system for external leaks or damage. Repair /replace as necessary. Turn the ignition off. 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 Install the Miller Tool #8978 Fuel Pressure Gauge. Refer to the Service Information FUEL DELIVERY Section. Start the engine and allow the fuel system to reach maximum pressure. Turn the ignition off. NOTE: Fuel specification is 334 KPa +/- 34 KPa (49 psi +/- 5 psi). Close the valve on the Fuel Pressure Gauge. Monitor the Upstream fuel pressure gauge for a minimum of 5 minutes. NOTE: The pressure should not fall below 241 KPa (35 psi) Does the Upstream gauge fall below the above specification? Yes Replace the leaking Fuel Injector(s). No Go To 8 8 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 CAUTION: After each Fuel Injector actuation, start the engine to clean the cylinder of fuel. Failure to do so could cause engine damage. Turn the ignition off. Install a Fuel Pressure Gauge. Start the engine and allow the fuel pressure to reach maximum pressure. Using the DRBIII, actuate the Fuel Injector for the cylinder that indicated the misfire. Monitor the fuel pressure gauge. Does the fuel pressure gauge indicate a drop in fuel pressure? Yes Go To 9 No Go To 10 9 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. No Go To 17 83

6 10 Turn the ignition off. Disconnect the Fuel Injector harness connector. NOTE: When a Misfire is detected for a particular cylinder, the PCM will shut down that cylinders Injector Control circuit. With the DRBIII, erase DTCs. Using a 12-volt test light connected to 12-volts, probe the Injector Control circuit. With the DRBIII, actuate the Fuel Injector. Does the test light blink/flicker? Yes Replace the Fuel Injector. No Go To Turn the ignition off. Disconnect the PCM harness connectors. Check the Injector Control circuit for an open, short to ground, and short to voltage. Was a problem found with the Injector Control circuit? Yes Repair the excessive resistance or short to ground in the Injector Control circuit. No Go To Turn the ignition off. 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 Raise vehicle on hoist, and disconnect the fuel pressure line at the fuel pump module. Install the fuel gauge between disconnected fuel line and the fuel pump module. With the DRBIII, actuate the ASD Fuel System test and observe the fuel pressure gauge. NOTE: Fuel pressure specification is 339 KPa +/- 34 KPa (49 psi +/- 5 psi). Is the fuel pressure within specification? Yes Repair or replace fuel supply line as necessary. No Go To Turn the ignition off. 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 Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer. Is the Fuel Inlet Strainer plugged? Yes Replace the Fuel Pump Inlet Strainer. No NOTE: Before continuing, check the Fuel Pump Module harness connector terminals for corrosion, damage, or terminal push out. Ensure the ground circuit is operating properly. Repair as necessary. Replace the Fuel Pump Module. 84

7 14 Turn the ignition off. Remove the ignition wire. Measure the resistance of the ignition wire. Is the resistance below 10K ohms? Yes Go To 15 No Replace the Ignition Wire. 15 Turn the ignition off. Disconnect the Ignition Coil harness connector. Remove the Fuel Pump Relay or ASD Relay. Using a 12-volt test light connected to 12-volts, probe the Ignition Coil Control circuit. Crank the engine for 5 second while observing the test light. NOTE: The resistance of the primary Ignition Coil on a 2.4L is 0.51 to 0.61 of an ohm and the 4.0L Primary Coil Rail resistance is 0.53 to 0.63 of an ohm at 77 F (25 C). Does the test light brightly blink/flicker? Yes Replace the Ignition Coil. No Go To Turn the ignition off. Disconnect the PCM harness connectors. Check the Coil Control circuit for an open, short to ground, and short to voltage. Was a problem found with the Coil Control circuit? Yes Repair the Coil Control circuit. No Go To NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits. If there are no possible causes remaining, view repair. Repair Replace and program the Powertrain Control Module per Service Information. 85

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