Piezo injectors

N43/N53/N54 and other direct injection engines uses not “classical” (coil – electromagnetic), but piezoelectric (material, which changes size, if affected by voltage) injectors. Piezoelectric injectors has been chosen because of instant reaction, which allows to execute multi-point (several injection cycles) injection mode.

BMW piezo injector

This time we will talk only about differences.

Each injector has been measured in factory by two flow curve points (by short and by infinitely long injection time),and measurements are recorded on injector’s body.

BMW piezo injector flow rate coding

Exact data calibration format is not available – it’s producers secret.

According to directions, we can assume, that:

2XX: reaction time (injector offset correction data) measurements;

5XX: flow rate correction data (multiplicative correction).

According to descriptions of error messages for MSD80/81/87 control unit, data coding of injector productivity should be in following limitations:

52.9..70.8 mJ

1.55..2.86 mg/str

It’s critically important to register these data in DME.Why?

If we don’t register the injectors:

a) the maximum offset adaptation range is narrowed in idle run mode, and, although all cylinders as if are balanced, there is a huge possibility to “catch” error messages about inability to maintain the fuel mixture, error messages regarding CO catalytic converters etc.;

b) both in small load and large load vibration of engine will be present (because in these cases DME don’t carry out the individual adaptations), there is a huge possibility to “catch”misfire and error messages about it both in Homogeneous and Stratified charge mode, error messages regarding trim problems: lean or rich mixture, error messages regarding Lambda probes etc.


Related entry:

Injectors flow rate data coding

Cleaning of piezo injectors