Catalyst monitoring - Automobili Lamborghini Holding Spa ...

Automobili Lamborghini s.p.a. OBDII – MY 08 Section 1 Page 1OBD Group 8NL-VTest Group 8NLXV05.0406 – 8NLXV06.5474OBD DescriptionIssue date: 08/nov/2006Revision date:CATALYST MONITORING_____________________________________________________________________________________________________________

Automobili Lamborghini s.p.a. OBDII – MY 08 Section 1 Page 2OBD Group 8NL-VTest Group 8NLXV05.0406 – 8NLXV06.5474OBD DescriptionIssue date: 08/nov/2006Revision date:Basic theory and algorithm_____________________________________________________________________________________________________________

Automobili Lamborghini s.p.a. OBDII – MY 08 Section 1 Page 3OBD Group 8NL-VTest Group 8NLXV05.0406 – 8NLXV06.5474OBD DescriptionIssue date: 08/nov/2006Revision date:The strategy adopted to evaluate catalyst malfunctioning exploits the signals coming from twooxygen sensors (λ-sensors) located at the inlet and at the outlet of the catalyst (see picture below forL140/L147 exhaust system lay-out). The oxygen sensor upstream of the catalyst is the one normallyused for closed-loop engine control.O2 REAR ON/OFF SENSORO2 FRONT UEGO SENSORO2 REAR ON/OFF SENSORO2 FRONT UEGO SENSORExhaust system lay-out – Lamborghini L140 Engine_______________________________________________________________________________________O2 REAR ON/OFF SENSORO2 FRONT UEGO SENSORO2 REAR ON/OFF SENSORO2 FRONT UEGO SENSORExhaust system lay-out – Lamborghini L147 Engine_____________________________________________________________________________________________________________

Automobili Lamborghini s.p.a. OBDII – MY 08 Section 1 Page 4OBD Group 8NL-VTest Group 8NLXV05.0406 – 8NLXV06.5474OBD DescriptionIssue date: 08/nov/2006Revision date:As is well known, the signal coming from this sensor oscillates periodically from rich output to leanoutput. These oscillations are due to the feedback system that properly adjusts the air / fuel ratio close tostechiometric value.Despite these cyclic variations, conversion efficiency of the three main pollutants CO, HC, and NO xstill remains high, due to the oxygen storage effect of catalyst components.Alumina and other components usually present in commercial catalysts show this "redox" behavior.To simply explain the phenomena we can say that in its oxidized state, although in a rich exhaust gasenvironment, it can provide oxygen for CO and HC oxidation, turning in the meantime to reduced state;when the exhaust cycles to lean condition, this reduced component can react with O 2 or NO X (thusremoving NO X directly or indirectly by reducing the O 2concentration). The oxidized component canthen oxidize CO and HC in the next rich cycle, and so on.So if the catalyst is working properly, that is with a high conversion efficiency, the output signal ofthe downstream oxygen sensor is not affected by cyclic variations as is the signal of the sensor located atthe inlet of the catalyst. The first diagram in the section 1.3 “Test procedures and results” shows thedifference between signals in a properly working catalyst. It is evident there is a difference inamplitudes of the oscillations.Thus monitoring the signals, and in particular the oscillation amplitude, of inlet and outlet oxygensensors, it is possible to evaluate the actual conversion efficiency of the catalytic converter.Lamborghini diagnostic strategy consists of monitoring amplitude of the upstream and downstreamsignal and summing these amplitudes in two accumulators for a prefixed time. If the catalyst is efficient,at the end of the sampling time the values of the two accumulators will be strongly different._____________________________________________________________________________________________________________

Automobili Lamborghini s.p.a. OBDII – MY 08 Section 1 Page 5OBD Group 8NL-VTest Group 8NLXV05.0406 – 8NLXV06.5474OBD DescriptionIssue date: 08/nov/2006Revision date:Mode/Service 6 communication_____________________________________________________________________________________________________________

Automobili Lamborghini s.p.a. OBDII – MY 08 Section 1 Page 6OBD Group 8NL-VTest Group 8NLXV05.0406 – 8NLXV06.5474OBD DescriptionIssue date: 08/nov/2006Revision date:The following chart shows the data related to the catalyst monitoring strategy in accordance whitspecification SAEJ1979 allowing access to the results for on-board diagnostic monitoring tests ofspecific components/systems that are not continuously monitored.J1979 CATALYST MONITOR SERVICE $06 DATATresholdErrorConversionTest ID Comp ID Bit TTL DescriptionINIT Value01 01 1 Ratio Lambda Front vs Rear bank dx 200 96 1/16/lsb01 02 1 Ratio Lambda Front vs Rear bank sx 200 96 1/16/lsb_____________________________________________________________________________________________________________