Spark plugs Always under high voltage

Extreme knocking events (mega knocking) in turbocharged engines with direct fuel injection can cause damage to the spark plug and engine. EVO spark plugs from Bosch are designed to be particularly robust for use in such engines.

Each spark plug is made for a specific area of application:

• Nickel spark plugs are ideally suited for use in engines with portfuel injection.
• Precious metal spark plugs are designed for the conditions in turbocharged engines with direct injection.

The welding process developed by Bosch with a

• continuous laser beam (Continuous Wave) and
• controlled heat output

ensures a particularly reliable and durable connection between the metals at the electrodes.

In hybrid engines, spark plugs are exposed to significantly cooler temperatures, which can lead to increased sooting and ignition problems. This is not a problem for Bosch spark plugs, as they have to undergo cold start tests that simulate such temperature behavior.

Bosch produces the ceramic granulate itself according to its own recipe. This ensures high mechanical and electrical resistance of the insulator.

A grinding wheel gives the soft ceramic insulators their characteristic outer shape.
 

After the burning process, the spark plugs are tested to ensure that the given specifications have been met. If the insulator is free of defects, the voltage flashes glide across the surface from top to bottom without penetrating the insulator.

The ceramic insulator is given its inscription, the typical Bosch color rings and a protective glaze.

This glaze prevents dirt adhesion and thus reduces the risk of leakage currents.

In modern spark plugs, a precious metal alloy, usually platinum or iridium, is applied to the center electrode and, where applicable, also to the ground electrode using special welding processes. This increases the wear resistance of the electrodes.

The terminal stud is pressed into the ceramic insulator at 800 °C, while a liquid glass sealant ensures a stable connection between the two components. This ensures that the spark plug remains gas-tight throughout its entire service life.

The ground electrode is bent precisely to the required gap to the center electrode and checked using a camera system. Readjustment by the workshop is not necessary – this saves time during installation.

1. Remove the spark plug from the packaging – do not grease or oil the thread. 
2. Screw the spark plug into the cylinder head by hand until it is seated. 
3. Tighten the spark plug with a torque wrench. 
4. Observe the defined and type-specific torque. 

Use a rubberized or magnetic spark plug socket and extension of the correct size to prevent

• the spark plug to fall out or
• slipping too deep into the tool
• being damaged during installation

1. Not changing all spark plugs at the same time 
2. Not cleaning the surrounding area with compressed air 
3. Readjusting the electrode gap
4. Using lubricant
5. Not using a torque wrench