Monitor Strategy Description

This function is used for functional diagnosis of the EGR system and to adapt the EGR valve. The strategy is based on manifold pressure measurements during fuel cut off conditions while the EGR valve is activated at different positions. This strategy operates once per driving cycle when conditions to activate the function are fulfilled. If fuel cut off conditions do not last long enough, it is possible to run the strategy in two steps. One step is the preferred solution. At the moment, the two steps solution is not validated. At the end, a filtered adaptive coefficient can be calculated to adapt the EGR valve.

For diagnosis, three symptoms can create a EGR error:

• Constant flow in the system
• Leakage in the EGR system
• Too much or not enough EGR flow in the system