Engine smooth running control procedure
The signal from the crankshaft position/rpm sensor is used to evaluate the rotation of the crankshaft on completion of each combustion cycle. Smooth running control corrects the speed differences of the individual cylinders caused by differences in the injection quantities and the cylinder efficiency. This is accomplished by rapid addition of controlled correction injection quantities for each cylinder. The correction quantities per cylinder are within a maximum range of 10 mm3 stroke/cylinder.
Smooth running control is only active in operating range close to idle speed.
Measuring engine smooth running control
Engine smooth running measurement can be used to read out the correction injection quantities for all cylinders. Engine smoothness measurement can be included in the test plan by means of:
– Service functions
– Digital Diesel Electronics
– Measuring engine smoothness
or by selecting the following functions:
– Drive
– DDE 4.0
– Measuring engine smoothness
Engine smoothness measurement: evaluation
Always begin by checking all fault-memory entries with the appropriate test modules. Always start troubleshooting at the cylinder with the highest correction quantity, because defective cylinders have a detrimental effect on the smooth running of the next cylinders in the firing sequence.
Quantities up to approx. 5 mm3 stroke/cylinder are considered to be non-critical. Higher correction values could be due to causes such as poor compression or a defective injector.
