Function

The quickest possible check can be made within the scope of the diagnostic. Because all the cables are already unclamped anyhow, a compression test is carried out through the current which the starter needs when starting the engine.

How it works

Although it is not precise, it does however, give an indication of possible defects. Perhaps it can prevent more serious damage. However, care is to be taken, because the tester must switch off individual cylinders during starting. Unfortunately however, only the ignition. If one does not disconnect the electrical connections to the injector valves, unburnt fuel reaches into the catalytic converter and can damage it.

Above can be seen, the partial figure of a Bosch FSA 560. In this case the necessary currents relating to the individual cylinders and the suitable limit values can already be seen. The second cylinder has obviously strained the starter distinctly less than the others. In this case strain means, that the starter needed less effort (current) to bring this cylinder through the compression stroke. A clear indication, however, something that needs further attention. 09/09