Introduction to Maserati
Quattroporte
Post-cat Lambda monitoring: The Lambda value down-stream of the catalytic converters is monitored by LSF type oxygen sensors (two-level sensors). These Oxygen sensors are less precise than LSU type sensors, and they are utilised primarily for diagnostic purposes. The Lambda value down-stream from the catalytic converters is used to: •
Check proper operation of the catalytic converters: In the event of detection of low efficiency of the catalytic converters, the Motronic ECU stores a DTC and illuminates the MIL warning light.
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Check proper operation of the Oxygen sensors up-stream of the catalytic converters (plausibility check).
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Provide a minor contribution to the Fuel Trim.
Slow Down strategy: •
The catalytic converters may be damaged if the temperature rises excessively.
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A mathematical model integrated in the ECU makes it possible to calculated the temperature of the catalytic converters in real time.
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The parameters utilised for the calculation are as follows: engine coolant temperature, ambient temperature, engine load, ignition advance and Lambda value.
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The calculated temperature allows the ECU to protect the system from serious problems by implementing suitable strategies
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When the calculated temperature reaches 980°C the Slow Down warning light flashes on the dashboard to alert the driver to the presence of a critical situation.
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When the calculated temperature reaches 1040°C the Slow Down warning light remains steadily illuminated and the ECU switches off the engine. Higher catalytic converter temperatures would damage the converters and may result in a fire outbreak.
Maserati Academy
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