Fault criteria, fuel evaporation M96
|
|
Fault criteria, fuel evaporation M96
|
Diagnosis is carried out once per trip and its purpose is to determine whether the
electronic control module can control a flow through the purge valve.
Closed loop or idle speed control should be affected when the conditions for diagnosis
are fulfilled and the purge valve is activated.
Diagnosis starts by checking the additional fuel obtained from the purging process. If
the additional fuel is more than 10%%, the result of the diagnosis is OK. If the additional fuel is
less than 10%%, diagnosis continues by stopping regular purging. Closed loop and idle speed
control mean values are then stored in the memory. Purging starts and the pulse ratio is
increased until a sufficient change in the closed loop or idle speed control can be
observed.
If no change is large enough, it is assumed that the purging flow contains no
hydrocarbons and that idle speed control has been disturbed. A new reference value for idle
speed control is now stored in the memory. Purging is interrupted and the change in idle
speed control observed. If the change is still not large enough, the fault criteria are satisfied.
The electrical circuit of the valve is also monitored continuously in accordance with the
On-Board Diagnostics I model.
|
•
|
Diagnosis not yet performed this
trip
|
|
•
|
Transition diagnosis of front heated oxygen sensor OK
|
|
1.
|
Fuel from purge < 10%% of
consumption
|
|
3.
|
Store reference value:
-closed loop
-idle speed control
|
|
4.
|
Activate purge valve and increase flow
|
|
5.
|
Closed loop decreases > 6 percentage points or idle speed control decreases
> 1 percentage point
|
|
6.
|
Store reference value:
-idle speed control
|
|
8.
|
Idle speed control
increases > 1 percentage point
|
|
9.
|
Function monitored this trip. Resume to ordinary purge
|
|
10.
|
Fault criteria for EVAP fulfilled
|
