Engine fault diagnostics (BMW 5 Series E39)

When the engine does not start, a systematic approach is needed to identify the fault. In general, in order for a gasoline engine to start, two prerequisites must always be met: the fuel-air mixture must enter the cylinders, and there must be a spark on the spark plugs. Therefore, first of all, it is always necessary to check whether fuel is supplied at all. How to act in this case is described in the sections "Power supply system" and "Petrol injection system".

To determine whether there is a spark, you need to unscrew the spark plugs, insert them into the tips and individually close the body of each spark plug to ground. In this case, hold the tip of the spark plug or the high-voltage wire with your hands, but with a well-insulated clamp. Ask an assistant to start the engine.

Caution: To prevent damage to the catalytic converter, it is necessary to disable gasoline injection. To do this, remove the fuel pump relay.

Caution: Observe safety regulations when working with the electronic ignition system. For a diesel engine, check the preheating system and the fuel supply system.

Malfunction: The engine starts poorly or does not start at all.



This publication was borrowed from an online resource: «BMWMAN.ru»