Pinpoint Test A: Misfire Pinpoint Test

Check the Powertrain control module (PCM) for related engine system DTCs and refer to relevant DTC index. If DTCs relating to any sub-system are present then these must be addressed before continuing with this pinpoint test e.g. Ignition system (including crank shaft sensor), Fuelling system (includes fuel system too lean/rich)

1. Using the Jaguar Land Rover Approved Diagnostic Equipment, run the Powertrain - Misfire - Cylinder Identification  application

Can a persistent  misfire be confirmed

• Yes  : Proceed to next step
• No  : If the misfire is not present, ensure conditions required to replicate the misfire are understood and repeat the test

  Consider the following:

  DTC snapshot information: Engine temperature, Engine speed, Vehicle speed, Time since the engine was started Driving conditions when the misfire occurred

1. Inspect the wiring harness for the ignition coils and fuel injectors. Ensure that the electrical connector pins are not backed out or corroded and the electrical connectors latch correctly

Have any wiring harness or electrical connector faults been identified?

• Yes  : Rectify the fault as required

  Repeat test step  1 (CHECK FOR MISFIRE COUNTS)

• No  : Proceed to next step

1. Swap the ignition coil from the affected cylinder(s) with a coil from a known good cylinder (do not remove the spark plug)
2. Repeat test step  1 (CHECK FOR MISFIRE COUNTS)

Has the misfire changed cylinder position?

• Yes  : Check and install a new ignition coil as required

  Repeat test step  1 (CHECK FOR MISFIRE COUNTS)

• No  : Proceed to next step

1. Swap the spark plug(s) from the affected cylinder(s) with a spark plug from a known good cylinder
2. Repeat test step  1 (CHECK FOR MISFIRE COUNTS)

Has the misfire changed cylinder position?

• Yes  : Check and install new spark plug(s) as required

  Repeat test step  1 (CHECK FOR MISFIRE COUNTS)

• No  : Proceed to next step

1. Using an oscilloscope check the actuation signal from the Powertrain Control Module (PCM) to the ignition coil
2. Compare the affected cylinder actuation signal for plausibility against known good cylinder actuation signals

Is the actuation signal for the affected cylinder plausible?

• Yes  : Proceed to next step
• No  : Refer to the electrical circuit diagrams and check the affected cylinder ignition coil circuit for short circuit to ground, short circuit to power, open circuit, high resistance

  Inspect the electrical connectors for signs of water ingress and pins for damage and/or corrosion

1. Using the Jaguar Land Rover Approved Diagnostic Equipment, run the Powertrain - Adaptive Fuel Trim Display  application
2. Check the short term and long term fuel trims

Does the application show the values within tolerance?

• Yes  : Proceed to next step
• No  : Using the Jaguar Land Rover Approved smoke machine, check the air intake system and vacuum hoses for leakage, blockage and mechanical integrity

  Check and install new air intake or vacuum system components only as required

  Repeat test step  1 (CHECK FOR MISFIRE COUNTS)

1. Using the Jaguar Land Rover Approved Diagnostic Equipment, check datalogger signal 0x0504 - Air Flow Sensor Bank 1
2. Using the Jaguar Land Rover Approved Diagnostic Equipment, check datalogger signal 0x0505 - Air Flow Sensor Bank 2
3. Compare the sensor values at idle and part load

Are the sensor values comparable between bank 1 and bank 2

• Yes  : Proceed to step  9 (SWAP FUEL INJECTORS CYLINDER TO CYLINDER)
• No  : Proceed to next step

1. Swap mass air flow sensors bank to bank
2. Using the Jaguar Land Rover Approved Diagnostic Equipment, check datalogger signal 0x0504 - Air Flow Rate From Mass Air Flow Sensor Bank 1
3. Using the Jaguar Land Rover Approved Diagnostic Equipment, check datalogger signal 0x0505 - Air Flow Rate From Mass Air Flow Sensor Bank 2
4. Compare the sensor values at idle and part load

Are the sensor values comparable between bank 1 and bank 2

• Yes  : Proceed to next step
• No  : Refer to the electrical circuit diagrams and check the mass air flow sensor circuit for short circuit to ground, short circuit to power, open circuit, high resistance

  Inspect connectors for signs of water ingress and pins for damage and/or corrosion

  Check for restricted air flow

  Check and install a new mass air flow sensor component only as required

  Repeat test step  1 (CHECK FOR MISFIRE COUNTS)

1. Swap the fuel injector(s) from the affected cylinder(s) with a fuel injector from a known good cylinder
2. Repeat test step  1 (CHECK FOR MISFIRE COUNTS)

   Has the misfire changed cylinder position?

   • Yes  : Check and install new fuel injector(s)

     Only the fuel injector for the corresponding DTC cylinder referenced should be replaced

     Repeat test step  1 (CHECK FOR MISFIRE COUNTS)

   • No  : Proceed to next step

1. Where available, using the Jaguar Land Rover Approved Diagnostic Equipment, run the Inline Diagnostic Unit 2 relative compression test  application, available on the following vehicles:

• AJ126 and AJ133:  L405, L494, X152, X260, L319 MY14>, X250 MY13>, X351 MY13>
• For vehicles not covered by the diagnostic tool compression test, refer to TOPIx section 303-00 Cylinder Compression Test 

Were the compression test values within limits?

• Yes  : proceed to next step
• No  : Carry out a cylinder leakage test to identify the area of compression loss e.g. cylinder or valve issue

1. Other possible causes:

• Crankshaft position sensor incorrect installation
• Reluctor ring mechanical damage at the flywheel
• Crank case ventilation system blockage or leakage

Were any of the above issues identified?

• Yes  : Rectify the fault as required

  Repeat test step  1 (CHECK FOR MISFIRE COUNTS)

• No  : Reconfirm the customer issue, ensure conditions required to replicate the misfire are understood and repeat the test