Sprinter 3500 L5-2.7L DSL Turbo (2004)
signals to perform the following functions for optimized closed loop control and monitoring of emissions related components:
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Injection valve quantity drift compensation in partial load range: the oxygen content in the exhaust is calculated from the air mass and from
injection quantity signal and is compared to the air-fuel ratio as measured by the sensor. If the calculated air-fuel ratio differs from the measured
air-fuel ratio, the is no correction of the injection quantity but the EGR rate and boost pressure are adjusted to the actual injection quantity.
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Injection valve quantity drift compensation in full load range: this function is to limit the maximum injection quantity for engine protection. The
injection quantity signal is compared to the injection quantity calculated from the oxygen sensor signal and MAF signal. If the comparison shows
that the actual injection quantity is too high, it is limited to the maximum permissible injection quantity
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Air-fuel ratio controlled smoke limiter (full load): the smoke limiter limits the injection quantity on the basis of the air-fuel ratio permissible at the
smoke limit depending on the measure mass air flow and the calculated EGR rate. As a consequence, the generation of smoke due to an excess
injection quantity is avoided under all operating conditions. At the same time, the oxygen sensor signal is used to ensure that the air-fuel ratio is
adjusted accordingly.
A function referred to as air flow sensor drift compensation detects and corrects the possible drifting of the MAF sensor by comparing the air mass
measured by the MAF with the projected air mass as it is calculated by the ECM in consideration of various influencing conditions. It is the air flow
drift compensation that gives the MAF air mass measurement the precision needed to use it for the function mentioned above. The high precision of the
MAF measurement enables the calculation of the actual injection quantity from the measured air mass and from the oxygen sensor signal in order to
correct injection quantity. The MAF signal can also be used as a input parameter for the smoke limiter.
