The regeneration sequences are variable. Frequency depends on driving conditions - but generally longer journeys with less frequent stopping and starting and at consistent speeds will result in longer distances before regeneration. This will be in part to the naturally higher exhaust gas temperatures at speed that allow the particles to be burned off without assistance.
Generally, as members should know, we don't allow discussions about emissions defeating of any kind as you rightly acknowledge Corne
I would point out though, that the EGR system is here at present, like it or not, but it does have a self-checking / cleaning and anti jamming strategy.
This is how a typical system does this:
Initialisation of the stops of the electric EGR valve
To mitigate ageing and clogging of the EGR valve, the engine ECU performs an automatic initialisation of the lower stop when the valve is closed (during full load, foot off or power latch).
The upper stop is calculated by adding 3 V to the position registered at the lower stop, the upper stop being updated at each initialisation of the lower stop. Taking account of the stop positions initialised automatically and comparing them with the original position initialised at the factory, the engine ECU adapts the setting for control of the EGR valve. (Initialisation of stops is not possible if the battery voltage is lower than 10 V or higher than 14 V).
Cleaning of the electric EGR valve
To prevent soiling of the electric EGR valve, there is a cleaning phase on switching on the ignition. This cleaning phase consists of 5 successive opening and closing cycles.
At the end of the cleaning cycle, the engine management ECU tries to reach the upper stop (maximum opening) of the electric EGR valve:
- If during this attempt a blockage is detected, the cleaning cycle is repeated
- If, after this second attempt, the valve remains stuck, a fault appears
Cleaning of the by-pass of the EGR Heat Exchanger
The engine ECU operates the cleaning (2 up/downs) of the by-pass of the EGR heat exchanger when the engine is running.
Cleaning is activated if the following conditions are met:
- Deceleration (Engine speed between 4000 and 1200 rpm)
- Coolant temperature between 60°C and 120°C
Antisticking the electric EGR valve
The engine ECU estimates the state of sticking of the electric EGR valve, as a function of the following factors:
- Speed of movement of the gate of the electric EGR valve
- Errors in regulation of the position of the electric EGR valve
If the electric EGR valve begins to stick or sticks, the engine ECU controls the electric EGR valve via a conventional control signal, followed by a vibratory signal to make the electric EGR valve vibrate and thus avoid sticking.
The amplitude of the vibratory signal depends on the degree of sticking detected by the engine ECU. The antisticking strategy is used only during phases where the electric EGR valve is being operated.
