Advances in Injector Test/Repair

Recent parts programmes at Bosch have led to the release of spare parts for two stage injectors and step body style injectors. The release of the EPS 100 in conjunction with these parts programmes has led to the ability to test and repair these items.

Bosch 2 Stage Injectors

The Technology

Two-stage injector technology has been around for years. Each injector effectively has two opening pressures, which will change the flow of fuel to the combustion chamber at a predetermined point. As a predecessor to common rail injectors this purely mechanical process does not have the finite control of later systems.

Injector Operation

At opening pressure P1 the nozzle needle lifts a set distance L1 that allows fuel to flow into the combustion chamber at a predetermined flow rate.

As the line pressure increases to P2 (a higher opening pressure) the needle will lift further to L2 (a longer travel), which increases flow to the combustion chamber.

This early form of injector allowed a type of ‘rate shaping' to effect a better cleaner combustion with improved drivability and fuel consumption.

Repair Concept

Historically this type of injector was not repairable, leading to costly exchange or new units being required. As a wear and tear item this concept has now been greatly improved to allow a repair. Each injector is fitted with a new nozzle and set to pressure using EPS100.

A repair is generally about half the price of an exchange unit and carries the coveted Bosch parts warranty.

Step Body Injectors

These injectors were generally designed for heavy truck applications to be placed to inject as close to the centre of the combustion chamber as possible. This type of short side entry injector is now repairable with new parts in conjunction with the EPS 100. These injectors have new nozzles fitted and are then checked for concentricity using a special Bosch tool. This gauge ensures accurate nozzle placement for accurate spray into the combustion chamber.

Applications

Bosch 2 Stage Injectors

Scania, Audi, Ford, VW, BMW, Renault, Vauxhall, Mercedes, Kia, Volvo Penta, Rover, Citroen, Peugeot, Perkins, Land Rover.

Stepped Body Injectors

Renault (MACK), Mercedes Benz (Actros/Atego), MAN (TGA Range)

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