Cold Start Emission Reduction Strategy Monitoring

.11.00.00 Cold Start Emission Reduction Strategy Monitoring

.11.01.00 General Description
The key parameters in our cold start emission reduction strategy (CSERS) are controlled by components which are included in and covered by the OBD II system. Any malfunction of one of these components would be indicated by the MIL without regard to its usage in the CSERS.

The fuel system controls the cold start of the engine based on throttle angel and engine speed. The throttle angel during cold start is adjusted based on the signals from MAF and ambient pressure sensor and intake air temperature.

The key parameters used for the quick catalyst heat-up during the first portion of a cold started driving cycle are as follows:
1. engine speed
2. fuel mixture (engine Lambda)
3. ignition timing
4. camshaft position

The key parameters are achieved in their ranges by the engine management system based on components which are already monitored by the OBD system. The attached table shows the influence of components on the key parameters and identifies the monitoring functions running during cold start as well as under the condition of a warmed-up engine.

The components with influence on the key parameters for the warm-up strategy are as follows:
1. Injection valves
2. Throttle unit
3. MAF
4. Ambient pressure sensor
5. Intake air temperature sensor
6. Ignition coils
7. Variable valve timing system
8. Camshaft/crankshaft alignment
9. Phase sensor
10. Engine speed sensor

.11.02.00 Monitoring function description
The calibration of the monitors used during cold start is the same as used later on a warmed-up engine. All of the components listed above are monitored by the OBD system during cold start at least for circuit continuity.
The components with influence on injection and ignition are also monitored by the misfire diagnostic function during the cold start. During a cold start condition a pull-back on ignition retard is allowed only in certain range. This range will be determined by definition of the maximum value for ignition retard.
Under closed loop condition monitoring is additionally supported by rationality functions using the signal of the oxygen sensor (e.g. injection valves monitored by the fuel system, rationality checks for throttle unit, ambient pressure sensor and intake air temperature are performed in comparison to the mass air flow meter).

.11.03.00 Charts and flow charts
The parameters with determine cold start conditions are:
1. Mass air integral below threshold
2. Engine coolant start temperature within an range
3. Altitude below threshold