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Home >> Chrysler >> 2009 >> PT Cruiser Limited >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> DTCS P0135 To P0440 - Gas >> P0301-Cylinder 1 Misfire >> Diagnostic Test

Diagnostic Test

  1. CHECKING FOR CYLINDER MISFIRE CONDITION PRESENT 
    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.
    NOTE: Reviewing the vehicle repair history may aid in the repair of the misfire condition.
    1. Engine running.
    2. Observe the WHICH CYLINDER IS MISFIRING screen and identify the cylinders that have a misfire present.

      Is there a misfire present at this time?

      Yes 

      • Go to step  2

      No 

  2. VISUAL AND PHYSICAL 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 Powertrain Control Module (PCM) will shut down that cylinders Injector Control circuit.

    Visually and physically inspect the engine for any of the following conditions:

    • A worn serpentine belt.
    • Binding Engine-Driven accessories.
    • A misaligned water pump, P/S pump and A/C compressor pulleys.
    • Improper CKP sensor mounting.
    • Poor connector/terminal to component connection. i.e., CKP sensor, Fuel Injector, Ign coil, etc.
    • Vacuum leaks.
    • Restricted Air Induction system.
    NOTE: Verify the integrity of the powers and grounds for the PCM.

    Were any of the above conditions present?

    Yes 

    No 

    • Go to step  3
  3. IGNITION SYSTEM OPERATION 
    1. Turn the ignition off.
    2. Disconnect the Ignition wire from the spark plug.
      NOTE: Before continuing, inspect the ignition wire for damage or carbon tracking. Replace as necessary.
    3. Install a spark tester to the ignition wire.
    4. While cranking the engine, observe the spark coming from the spark tester.
      NOTE: A crisp blue spark should be generated that is able to jump the gap of the spark tester.

      Is good spark present?

      Yes 

      • Go to step  4

      No 

      • Go to step  14
  4. SPARK PLUG 
    1. Turn the ignition off.
    2. Remove the Spark Plug.
    3. Inspect the Spark Plug for the following conditions:
    • Cracks
    • Carbon Tracking
    • Foreign Material
    • Gap size out of specifications
    • Loose or broken electrode
  5. CHECKING FUEL PRESSURE 
    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. Install a fuel pressure gauge.
    2. Start the engine and observe the fuel pressure reading.
      NOTE: Fuel pressure specification is 400 kPa +/- 34 kPa (58 psi +/- 5 psi).

      Choose a conclusion that best matches your fuel pressure reading.

      Within Specification 

      • Go to step  6

      Below Specification 

      • Go to step  12

      Above Specification 

  6. CHECKING FUEL LEAK DOWN 
    1. Perform the diagnostic procedures for FUEL PRESSURE LEAK DOWN and FUEL DELIVERY SYSTEM OUTPUT - FLOW TEST. Refer to Non-DTC Diagnostics/Driveability - Gas - Diagnosis and Testing .

      Were any problems found?

      Yes 

      No 

      • Go to step  7
  7. 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 actuation of the Fuel Injector, start the engine to clear the cylinder of fuel. Failure to do so could cause engine damage.
    1. Install a Fuel Pressure Gauge to the fuel rail.
    2. Start the engine and allow the fuel pressure to reach maximum pressure.
    3. Turn the engine off, leaving the ignition on.
    4. Using the scan tool, actuate the Fuel Injector for the cylinder that indicated the misfire.
    5. Monitor the fuel pressure gauge.

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

      Yes 

      • Go to step  8

      No 

      • Go to step  9
  8. CHECKING FOR POSSIBLE MECHANICAL PROBLEM 

    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

    Are there any engine mechanical problems?

    Yes 

    No 

  9. (K343) ASD RELAY OUTPUT CIRCUIT 
    Fig 1: Checking ASD Relay Output Circuit
    GC0117204Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Disconnect the Fuel Injector harness connector.
    3. Ignition on, engine not running.
    4. With the scan tool, actuate the ASD Relay.
    5. Using a 12-volt test light connected to ground, probe the (K343) ASD Relay Output circuit at the Fuel Injector harness connector.

      Does the test light illuminate brightly?

      Yes 

      • Go to step  10

      No 

  10. FUEL INJECTOR 
    Fig 2: Checking Injector Control Circuit
    GC0117222Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Disconnect the Fuel Injector harness connector.
    3. Ignition on, engine not running.
    4. Using a 12-volt test light connected to 12-volts, probe the (K11) Injector Control circuit.
    5. With the scan tool, actuate the Fuel Injector.

      Does the test light blink/flicker?

      Yes 

      No 

      • Go to step  11
  11. INJECTOR CONTROL CIRCUIT 
    1. Turn the ignition off.
    2. Disconnect the Fuel Injector harness connector.
    3. Disconnect the PCM harness connectors.
      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 PCM Pinout Box 8815 to perform diagnosis.
    4. Check the (K11) Injector Control circuit.

      Was a problem found with the Injector Control circuit?

      Yes 

      No 

  12. RESTRICTED FUEL SUPPLY LINE 
    1. 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 pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.
    2. Raise vehicle on hoist and disconnect the fuel pressure line at the fuel pump module.
    3. Install the Gas Fuel Pressure Decay Tester 8978A between the disconnected fuel line and the fuel pump module.
    4. Ignition on, engine not running.
    5. With the scan tool, actuate the ASD Fuel System test and observe the fuel pressure gauge.
      NOTE: Fuel pressure specification is 400 kPa +/- 34 kPa (58 psi +/- 5 psi).

      Is the fuel pressure within specification?

      Yes 

      No 

      • Go to step  13
  13. FUEL PUMP INLET STRAINER 
    1. 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 pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.
    2. Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer.

      Is the Fuel Inlet Strainer plugged?

      Yes 

      No 

  14. IGNITION WIRE 
    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 step  15

      No 

  15. (K344) ASD RELAY OUTPUT CIRCUIT 
    Fig 3: Checking ASD Relay Output Circuit
    GC0117223Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Disconnect the Ignition Coil harness connector.
    3. Ignition on, engine not running.
    4. With the scan tool, actuate the ASD Relay.
    5. Using a 12-volt test light connected to ground, probe the (K344) ASD Relay Output circuit at the Ignition Coil harness connector.

      Does the test light illuminate brightly?

      Yes 

      • Go to step  16

      No 

  16. IGNITION COIL 
    Fig 4: Checking Ignition Coil Control Circuit
    GC0117224Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Disconnect the Ignition Coil harness connector.
    3. Using a 12-volt test light connected to 12-volts, probe the (K19) Ignition Coil Control circuit.
    4. Crank the engine for five seconds while observing the test light.

      Does the test light blink/flicker?

      Yes 

      No 

      • Go to step  17
  17. COIL CONTROL CIRCUIT 
    1. Turn the ignition off.
    2. Disconnect the Ignition Coil harness connector.
    3. Disconnect the 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 PCM Pinout Box 8815 to perform diagnosis.
    4. Check the (K19) Coil Control circuit.

      Was a problem found with the Coil Control circuit?

      Yes 

      No 

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