P0307

P0307

Cylinder 7 Misfire Detected

Diagnostic conditions - V8
- Intake air temperature greater than -20°
- Engine speed between 400 and 6,500 rpm
- Load between 12 % and 39 %

Possible cause of fault
- Improper handling of a block heater

Fault in ignition system:
- Mechanical or electrical fault in spark plug
- Spark plug connector faulty
- Bar ignition module faulty

Fault in fuel/air mixture:
- Tank filled with incorrect fuel quality
- Tank driven empty
- Mechanical or electrical fault in injection valve
- Oxygen sensor faulty
- Fuel filter soiled
- Mechanical fault in fuel pump

Fault in exhaust system:
- Catalytic converter damaged (flow severely restricted)
- Kink in exhaust pipe
- Muffler faulty (flow severely restricted)

Fault in valve drive:
- Fault in timing adjustment of inlet camshaft (VarioCam)
- Outlet camshaft timing incorrect
- Hydro push rod faulty
- Valve seat or valve faulty

Fault in intake system:
- Leak in intake distributor

Diagnosis/troubleshooting

NOTE:
- The fault 'Random/Multiple Cylinder Misfire Detected' (P0300) causes the Check Engine MIL to light up if exhaust-relevant misfires were detected in one or more cylinders in two consecutive journeys.
- An initial note appears because the relevant cylinder is stored.
- A cycle of 1,000 crankshaft revolutions is evaluated in the case of exhaust-related misfires (in the case of misfiring that causes damage to the catalytic converters, the cycle amounts to 200 revolutions). The misfiring rates are compared with a threshold value. If the misfiring rate is greater than the threshold value, the fault is set.
- The 'Check Engine' warning light is switched on (permanent light) if the misfiring rate exceeds the threshold value in two (or three in the case of EOBD) consecutive 'driving cycles' in which the emission limit values are exceeded.
- The 'Check Engine' warning light flashes if the misfiring rate has the potential to cause permanent catalytic converter damage. If the misfire rate is no longer reached during the first journey, the MIL goes out. If the rate is reached during the next journey, the MIL flashes. If this misfire rate is subsequently no longer reached, the MIL changes to a permanent light.
- In the event of a short circuit to B+ or ground in the oxygen sensors ahead of the catalytic converter, the mixture becomes too lean or too rich. This can cause misfiring. If an oxygen sensor fault ahead of the catalytic converter is also stored in memory, first correct this fault and then road test the vehicle.
- It is possible that this cylinder is the only one to have exceeded the rough running threshold value for a fault entry, and that other cylinders are also close to being entered as faults. A comparison of the "rough running" actual values of each of the cylinders can provide information on this using the 9588 Porsche System Tester II. The cause of the fault may then have to be continued under fault code P0300 - Random/Multiple Cylinder Misfire Detected.
- If the battery was disconnected during troubleshooting or if the DME control module was removed, a sensor wheel must be adapted (range 1). It is only when this is done that misfires can be reliably detected by the DME.
- To do this, you must accelerate three times in fixed driving position Two and then allow the vehicle to coast to a stop, without switching the driving position or using the brake or accelerator (overrun disconnection phase).
- You can check whether the adaptation was performed in the 9588 Porsche System Tester II under "Actual values", "Status: Adaptation".