General
GENERAL- The Siemens (Conti) system already fulfils the PDTC requirements except the paragraph (d) (2.5). This means that after the monitor was completed with a no fault result, the error will be deleted directly. This will be fixed with MY 10.
IUMPR Statement:
The OBD II System of this test group is designed to comply with the provisions of CCR 1968.2, section (d)(3.2) requirements.
Overview:
Incrementing of numerator:
EVAP small leak:
To increment the numerator for small leak detection the following conditions have to be fulfilled:
a. If the system is tight, the numerator is incremented after a "worst case diagnostic time". This "worst case diagnostic time" is the maximum diagnostic time, witch could occur during a leak test. If the ignition is switched on during this time, the numerator is not incremented.
b. If the system is not tight and a small leak is detected the numerator is incremented directly after the leak detection.
EVAP rough leak:
To increment the numerator for rough leak detection the following conditions have to be fulfilled:
a. If the system is tight, the numerator is incremented after a "worst case diagnostic time". This "worst case diagnostic time" is the maximum diagnostic time, witch could occur during a leak test. If the ignition is switched on during this time, the numerator is not incremented.
b. If the system is not tight, a rough leak is detected an no refuelling is detected the numerator is incremented directly after the leak detection.
Front O2 sensor:
To increment the numerator a background monitor for sensor activity checks and response check will be considered. This ghost monitor will be related to the worst case times of each phase and step of the diagnosis.
a. If during this time the monitor conditions for the ghost monitor are met for the worst case condition (e.g number of amplitudes for slow sensor response), the system would have detected a failure. The numerator will be incremented.
b. If during this time the monitor conditions for the ghost monitor are not met, analogous to the normal function, the system would repeat the monitor. The numerator would not be incremented.
c. If during any repeated monitor the monitor conditions for the ghost monitor are met, for the worst case time, the system would have detected a failure. In this case the numerator will be incremented.
Catalyst efficiency:
When the monitor has been finished and the O2 sensor monitor has been completed, the numerator will be incremented.
VVT:
The numerator will be incremented, if the monitoring conditions are several times fulfilled.
Incrementing denominator:
The following signals are used for denominator incrementing:
(Each sensor for this purpose is monitored either as out of range, signal or rationality check)
General denominator:
Evap denominator:
Cold Start Reduction Strategy
The system is equipped with a cold start emission reduction monitoring strategy. It works as follows:
The Porsche system currently uses a combination of the following measures to enhance the catalyst warm-up:
- spark retard
- elevated idle speed
- retarded transmission shifts
- camshaft position
- variable valve lift
According to (e)(11.2.1), the individual component related to the above strategies has to be monitored. The table below demonstrates that all catalyst heating measures are covered by components which are monitored individually. The long term fuel system and the valve lift diagnosis, which need a lambda signal for monitoring, are finished after the catalyst warm-up phase. Errors will be detected before the next catalyst warm-up.
Overview:
Monitoring of idle speed
The monitoring of the idle speed is now also active during the cold start phase. The following P-codes are set in case of an error:
P050D: idle air control system RPM higher than expected during cold start phase
P050A: idle air control system RPM lower than expected during cold start phase
The following chart shows the working principle of the idle speed monitoring:
Spark retard
The spark retard is limited (fixed) during the catalyst heating phase. There is no diagnosis implemented.
The following chart explains the working principle:
Emission influence of spark retard during FTP-test
Influence on Emissions during 20 °C FTP-Test with aged Catalyst:
