Cold Start Emission Reduction Strategy Monitoring

2 Cold Start Emission Reduction Strategy Monitoring

The Monitoring of the Cold Start Emission reduction Strategy consists of several monitors:
- Cold Start Idle Air Control System
- Ignition angle efficiency monitoring
- Variable Valve Timing (see variable valve lift monitoring + variable camshaft timing control)
- Fuel pressure (see fuel pressure monitoring)

Some of them are derived from the monitors for normal engine operation and accordingly described in the same chapter as the monitor for normal engine operation.

2.1 Cold Start Idle Air Control System Monitoring

General Description:
The purpose of this diagnostics is to detect a deviation between the desired idle speed setpoint during catalyst heating phase and the actual engine speed at idle. In general it's the same monitor used for normal operation but it's completely independently operated and stores a different DTC.

2.2 Ignition angle efficiency monitoring in idle or trailing throttle

General Description
The purpose of this diagnostics is to detect a deviation between the ignition retardation requested by catalyst heating (as active part of the catalyst heating strategy) and the actual applied ignition retardation during the engine states idle and trailing throttle. The monitoring is based on the ignition angle efficiency. The ignition angle efficiency deviation is accumulated and normalized on the time spent in the engine states idle or trailing throttle. Malfunction is detected if the resulting quotient exceeds a threshold depending on the engines start temperature.

2.3 Ignition angle efficiency monitoring during part load

General Description
The purpose of this diagnostics is to detect a deviation between the ignition retardation requested by catalyst heating (as active part of the catalyst heating strategy) and the actual applied ignition retardation during the engine state part load. The monitoring is based on the ignition angle efficiency. The ignition angle efficiency deviation is accumulated and normalized on the time spent in the engine states idle or trailing throttle. Malfunction is detected if the resulting quotient exceeds a threshold depending on the engines start temperature.