Crankshaft sensor. Part 2

This time – one interesting nuance, which I observed in the situation when MSD80 detects a problem with the crankshaft sensor.

If MSD detects the inadequacy of signal of the crankshaft sensor or the signal is not identified at all, the DME doesn’t use the crankshaft sensor (till next driving session) and the engine works, using the camshaft sensors.

Self-evident – VANOS are turned off (control valves – closed, the camshafts are in their initial positions).

It’s harder to start the engine, it is more inert, with reduced torque, but – you will get to the service for sure.

The largest problem of DME in this mode: unlike the crankshaft pulley, which has several tenths of “teeth”, which inform DME regarding the turning speed and the position of the crankshaft, the rings of the camshaft have only several “teeth”. In addition – the camshaft turns 2 times slower than the crankshaft – it worsens the situation even more! Even if the “teeth” of the ring is used both in rise and fall moments, DME receives only several impulses on one turn of the crankshaft.

In such complete emergency mode – what interesting would be done by DME. In idle, for example? The evening of the mechanical efficiency of cylinders in idle is not possible, using the data of the flywheel ring (because the sensor, which reads these data).

For this reason, DME uses the chemical efficiency tests to even the idle!


The results of the chemical tests can be seen online: ../F5/Shift+F6/F3, first 3 lines.

The results of these tests are applied to injectors offset type corrections in idle mode (and are not recorded in the groups of results, shown below – they refer to the cold engine and partial load).

AT the same time, DME is not able to detect the mechanical efficiency of cylinders, and all menu registers of ../F5/F7 of turned-on engine indicate 0.

Here, even in such seemingly hopeless situations, BMW takes care so the engine would run max evenly!