Ignition System: Description and Operation

V8 DFI Engines

Ignition Coils







The Cayenne has static high-voltage ignition distribution with individual ignition coils attached directly to the spark plugs. The newly enhanced ignition coils in V8 DFI engines work according to the same principle as previous V8 ignition coils.

This system offers the following advantages:
- High level of ignition safety.
- Minimum electromagnetic interference with other electronic components.
- No requirement for ignition cables and distributor ignition.

The DME control unit activates the individual ignition coils individually in the firing order 1-3-7-2-6-5-4-8 for each cylinder. Safer ignition processes and therefore optimized power, together with minimized emissions and fuel consumption are obtained as a result of the measures and advantages described. All parts in this enhanced component are installed as a complete unit in a special rod ignition module housing. This is connected electrically and mechanically to the spark plug in the spark plug recess via the short high-voltage plug. The component is also secured mechanically using bolts. The ignition coil is sealed at the four-pin plug and in the spark plug recess to protect it from spray water.

Cayenne S Spark Plugs







The V8 naturally aspirated engine has nickel-yttrium spark plugs with four ground electrodes, which must be changed every 36,000 miles (60,000 km) or after 4 years according to the Technical Data.

The four ground electrodes are arranged around the ceramic insulator in these surface gap spark plugs. The sparks -1- cross the surface of the insulator -4- and arc across a small gas gap to the ground electrode -2-, which improves the ignition properties. The main advantage of the surface gap spark plugs is the self cleaning effect of the insulator foot tip, since any shunts that occur between the center electrode and the ground electrode through the surface gaps, in particular during a cold start, are eliminated.