General principal
NoteThe particle filter works without additive
The aim of the regeneration is to eliminate the soot retained on the walls of the particle emission filter
The regeneration is initiated by the engine management ECU (regeneration assistance) when the particle emission filter is clogged
Regeneration is possible if the temperature of the particle emission filter is higher than 600°C
This condition cannot be met during the normal operation of the vehicle
The engine management ECU manages the following elements continuously
- The condition of the particle emission filter by a Monitoring of the level of load of the particle emission filter function
- The regeneration assistance by a Regeneration assistance management function
- The condition of the engine oil by a Monitoring of the condition of the engine oil function
NoteThe regeneration assistance causes a degradation of the engine oil by dilution with fuel
Function: monitoring of the particle filter load level
Role of the particle emission filter load level monitoring function
- To determine the driving conditions
- To determine the condition of the particle filter (clogging level)
- To request activation of the regeneration assistance function, when required
- To ensure the effectiveness of the regeneration assistance function
Main information used for monitoring the particle filter
- Calculation of the weight of soot present in the particle filter
- Differential pressure between the pressure upstream and downstream of the particle emission filter (measure)
- Exhaust gas temperature (upstream of the catalytic converter)
- Exhaust gas temperature (downstream of the catalytic converter)
- Inlet air flow
- Information on mixture coming from the oxygen sensor
NoteThe first two pieces of data are dependent on the particle filter load level
Driving conditions
The driving conditions have a direct influence on the temperature of the exhaust gases and on the accumulation of soot in the particle emission filter
"A" road or motorway type driving
"B" urban type driving
"a" deposits (particles, soots, unburnt hydrocarbons, oil residues, etc.)
"b" filtered exhaust gases
Example "A"
- The flow volume of the exhaust gases is considerable
- The deposits form at the bottom of the particle filter
- The gases pass through the channels easily, the level of clogging of the particle emission filter is low
Example "B"
- The flow volume of the exhaust gases is low
- The deposits form in a stratified layer on the channels
- The gases pass through the channels with difficulty, the level of clogging of the particle emission filter is high
The engine management ECU determines the driving conditions according to the following parameters
- Vehicle speed
- Engine torque
- Engine speed
- Coolant temperature
- Air temperature at flowmeter
- Quantity of fuel injected
- Information on mixture coming from the oxygen sensor
"C" Engine torque
"D" engine speed
Driving conditions
- "E" acceleration
- "F" fast motorway
- "G" downhill
- "H" urban (at low speed)
- "J" urban
- "K" main road
- "L" motorway
Calculation of the weight of soot present in the particle filter
The engine management ECU integrates cartographies that model the mass of particles present in the particle emission filter, according to the type of driving the vehicle experiences
The engine management ECU calculates the emissions of soots from the vehicle during each driving episode
The calculation of the emissions of soots takes the following parameters into account
- Driving conditions
- Information on mixture coming from the oxygen sensor
- Vehicle mileage
- Vehicle speed
- Quantity of fuel injected
- Coolant temperature
- Air temperature at flowmeter
- Particle emission filter temperature
- Volume flow rate of exhaust gases
The volume flow of the exhaust gases is calculated from the following parameters
- Differential pressure between the pressure upstream and downstream of the particle emission filter (measure)
- Inlet air flow
- Atmospheric pressure
- Exhaust gas temperature (upstream of the catalytic converter)
- Exhaust gas temperature (downstream of the catalytic converter)
The engine management ECU continuously determines the weight of soot present in the particle emission filter and the level of clogging of the filter
Regeneration assistance activation conditions
The engine management ECU requests the activation of the regeneration assistance function in the following circumstances
- Weight of soot in the particle emission filter higher then 52 grammes (if the vehicle speed is below 85 km/h)
- Weight of soot in the particle emission filter higher then 42 grammes
- 5000 km travelled since the last regeneration
- 327,7 litres of fuel consumed since the last regeneration
- 250 hours of operation since the last regeneration
- Differential pressure higher than a threshold which depends on the flow of exhaust gas by volume (filter partially blocked)
The engine management ECU records a fault in the following cases
- Weight of soot in the particle emission filter higher then 58,5 grammes (filter overloaded)
- Weight of soot in the particle emission filter higher then 65 grammes (filter clogged)
Differential pressure
The differential pressure represents the pressure difference between the upstream input and the downstream output from the particle emission filter
The quantity of soots present in the particle emission filter causes the differential pressure to vary, which increases the accumulation of soots in the particle emission filter
"M" differential pressure
"N" volume flow rate of exhaust gases
"c" filter clogged (critical level)
"d" filter overloaded (alert level)
"e" filter partially blocked
"f" intermediate zone
"g" filter regenerated (nominal operation)
"h" filter punctured
The correspondence between the different statuses of the particle emission filter and the quantity of soot calculated by the engine management ECU is given by the following table
| minimum weight of soot | maximum weight of soot | status of the particle emission filter |
|---|---|---|
| - | 20 g | regenerated (nominal operation) |
| 20 g | 52 g | intermediate zone |
| 52 g | 58,5 g | filter partially blocked |
| 58,5 g | 65 g | overloaded |
| 65 g | - | clogged |
The differential pressure is also a safety element as regards the particle emission filter and the engine
The differential pressure is used by the engine management ECU to carry out the following checks
- To check the coherence of the calculation of the mass of soots
- To ensure the effectiveness of the regeneration assistance function
- To detect a fault in the particle emission filter (filter overloaded, clogged or holed)
NoteIn the event of an incoherence between the calculation of the mass of soots and the value of the differential pressure, a fault is forwarded
Filter punctured
The differential pressure measured is below a threshold which depends on the exhaust flow
Possible fault causes
- Incorrect information from the differential pressure sensor
- Exhaust line sealing fault, or of the upstream/downstream pressure information pipes
- Particle emission filter actually holed
- Particle emission filter removed
The engine management ECU interrupts any request for regeneration assistance and reports a fault accompanied by the illumination of the corresponding indicator light on the instrument panel
NoteThe "filter pierced" fault may be due to an excessive temperature during regeneration
Filter overloaded
The differential pressure measured is higher than a threshold which depends on the exhaust flow
Possible fault causes
- Regeneration assistance ineffective
- Incorrect information from the differential pressure sensor
The engine management ECU interrupts any request for regeneration assistance and reports a fault accompanied by the illumination of the corresponding indicator light on the instrument panel
The engine management ECU limits the flow of fuel injected and the engine speed to protect the engine
Filter clogged
The differential pressure measured is close to the maximum counter-pressure permitted by the engine
Possible fault causes
- Regeneration assistance ineffective
- Incorrect information from the differential pressure sensor
- The presence of condensation in the particle emission filter (possible during the first kilometres before the first regeneration)
The engine management ECU interrupts any request for regeneration assistance and reports a fault accompanied by the illumination of the corresponding indicator light on the instrument panel
The engine management ECU limits the flow of fuel injected and the engine speed to protect the engine
WarningIf the "filter clogged" fault is present, it is essential to find the origin of the fault, otherwise the filter or the engine will be damaged
Function: regeneration assistance management
Role of the regeneration assistance management function
- To manage the requests for regeneration from the monitoring function
- To activate the functions required for regeneration, according to the statuses of the monitoring function
- To check the effects of the regeneration on the engine operation
The regeneration consists of periodically burning the particles that have accumulated on the filter by increasing its temperature beyond the soot combustion threshold (600 °C)
The complete regeneration of the particle emission filter lasts between 20 minutes and 1 hour, depending on the weight of soot present in the particle emission filter
Regeneration
The regeneration assistance is a set of provisions managed by the engine management ECU, the aim of which is to increase the temperature of the exhaust gas to the regeneration threshold
When the monitoring function estimates that the mass of soots in the particle is considerable and the capacity of the engine to regenerate the particle emission filter (driving conditions, temperature, etc) is adequate, it requests the activation of the regeneration assistance
When each activation request is issued, the engine management ECU carries out the following operations
- Closing of the EGR (exhaust gas recycling) valve
- Activation of post-injection
- Manipulation of the air mixer
- Operation of the fan at maximum speed
The post-injections take place between 120° and 140° crankshaft rotation after top dead centre
The post-injections result in an increase in the quantity of unburnt hydrocarbons (HC)
The combustion of these hydrocarbons takes place in the exhaust line near the catalytic converter and the particle emission filter
The valve regulation of the inlet air increases the richness of the mixture and the temperature at the exhaust
NoteThe activation of electrical consumers by the engine management ECU regeneration assistance is not provided
During the regeneration the engine management ECU updates the level of load of soots of the particle emission filter
Regeneration in after sales
After sales regeneration assistance can be carried out using the diagnostic tool
To facilitate after-sales regeneration it is advised to activate the electrical consumers of the vehicle (heated rear window, lighting, etc.) in order to increase the engine load
During a regeneration in after sales, the engine management ECU updates the particle filter soot load level
Effects of regeneration assistance activation
The increase in the flow of fuel injected and of the temperature of the exhaust gas causes an increase in the engine torque
The following additional actions compensate for this effect
- Control of the turbocharger in order to limit the increase in the turbocharging pressure
- Delay of the main injection to limit the increase in the flow of fuel injected
Post-injection
In the presence of unburnt hydrocarbons (HC), the temperature of the exhaust gases increases
The temperature of the exhaust line rises progressively until it is permanently higher than the threshold for regeneration
Once the regeneration limit has been reached, post injection is maintained until all particles have been removed
NoteDuring the phases when the accelerator pedal is not pressed, the number and times of post-injections are increased to maintain the temperature of the particle emission filter
To maintain the same driving pleasure and prevent engine hesitation, the engine management ECU reduces the main injection time
Closure of the inlet air mixer unit - valve system
The inlet air mixer unit is controlled to meet the management requirements of the air flow in the particle emission filter regeneration phase
The air mixer unit varies the incoming airflow according to its degree of opening
The partial closure of the inlet air mixer unit allows the following operations
- Limiting the quantity of fresh air inducted by the engine
- Augmenting the combustion richness of the mixture
- Augmenting the engine load
- To aid the rise in temperature of the exhaust gases
NoteThe closing of the inlet air mixer unit is greater during the phases of release of the accelerator pedal to maintain the temperature of the particle emission filter
Degradation of the engine oil
The post injection takes place after the top dead centre of the piston which causes a dilution of fuel in the engine oil which is in the walls of the cylinder
The engine oil gradually degrades and its level increases in the sump
To avoid any operating conditions which pose a danger to the engine, the engine management ECU determines the level of deterioration of the engine oil
NoteThe changing of the oil is not based on the routine servicing schedule and must be carried out when the corresponding warning lamp flashes on the instrument panel, according to the use of the vehicle
The level of degradation of the engine oil is defined from the following parameters
- Number of regenerations of the particle emission filter since the last oil change
- Distance covered
- Number of the engine starts
- Number of starts with the engine cold
- Average value of the engine temperature
- Duration of the journeys
NoteOperation with the engine hot allows an evaporation of part of the diluted diesel fuel and therefore the partial regeneration of the properties of the oil
WarningThe engine oil deterioration parameter must be initialised after each oil change to prevent faults linked with an incorrect deterioration parameter
Driver's information function
Particle filter warning lamp
When starting, the indicator light corresponding to the particle emission filter comes on then goes off after several seconds
The indicator light remains on in the following circumstances: regeneration assistance ineffective
NoteThe indicator light does not come on at every request for regeneration assistance, but only when the driving conditions do not allow regeneration
In the event of prolonged idling, regeneration assistance is ineffective (exhaust gas temperature insufficient)
The engine management ECU requests the display of a message on the matrix of the instrument panel (risk of clogging of the particulate emission filter)
In this case it is advisable, as far as possible, to drive at a speed higher then 50 km/h until the warning lamp switches off, to permit regeneration of the particle emission filter
NoteComply with the law and the highway code in your country
Degradation of the engine oil
The engine management ECU controls the flashing illumination of the engine oil indicator light when the level of degradation of the engine oil requires an oil change
NoteFlashing of the engine oil warning lamp does not correspond to a fault in the engine lubrication system
It is advisable to change the engine oil within the next 1000 km following the flashing of the engine oil warning lamp
If the oil is not changed when a second degradation limit is reached, the engine oil indicator light remains on continuously and the performance of the engine is limited
Faults - back-up operating modes
The injection system changes to downgrade mode and reduces the flow of injected fuel and the engine speed in the following circumstances
- 3 unsuccessful attempts to regenerate the particle emission filter
- 90 minutes of operation of the particle emission filter in overloaded condition
- Fault on a component of the particle emission filter
- Particle filter clogged
- Engine oil deteriorated (oil change warning lamp flashing or more than 1000 km)
The engine management ECU can apply several engine performance limitation strategies in the event of a fault in a component of the particle emission filter or excessive deterioration of the engine oil
The engine performance limitation strategies authorise an operation of the engine but with limited engine speed and torque, the severity of the limitation depending on the fault
The engine ECU acts on the fuel flow regulation valve and on the injectors to reduce the flow of fuel injected
The engine management ECU acts on the turbocharger variable geometry actuator control solenoid valve to reduce the turbocharging pressure
The engine management ECU interrupts any request for regeneration assistance and reports a fault accompanied by the illumination of the corresponding indicator light on the instrument panel