Fault criteria, fuel evaporation M96 1/2
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Fault criteria, fuel evaporation M96 1/2
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Diagnosis is carried out once per trip and its purpose is to determine whether
leakage in the fuel evaporation system occurs which is greater than would be caused by a
hole with a diameter of 0.040". Included in the system are a tank pressure sensor and a shut-
off valve for supply air to the evaporative emission canister.
When the conditions for diagnosis are fulfilled and the supply air for the evaporative
emission canister is shut off, the purge valve should be able to control the tank
pressure.
Diagnosis starts by the tank pressure sensor value being stored. The shut-off valve for
the evaporative emission canister is then closed. Purging is stopped when the tank pressure
has dropped by 0.4 kPa. The speed with which the tank pressure rises is now observed. The
fault criteria are satisfied if a pressure drop of 0.4 kPa cannot be obtained within 10 seconds
or if tank pressure rises too quickly in 10 seconds from the time purging was stopped.
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Diagnosis not yet performed this
trip
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Transition diagnosis of front heated oxygen sensor OK
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Vehicle speed = 0 for 7 sec.
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Additional fuel from purging <10 of engine's fuel requirement.
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1.
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Store reference value:
-tank pressure
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2.
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Close evaporative emission canister's shut-off valve
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3.
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Tank pressure drops > 0.4 kPa within 10 seconds
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5.
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Tank pressure constant or rises very slowly for 10 seconds
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6.
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Function monitored this trip. Resume to ordinary purge
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7.
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Fault criteria for EVAP fulfilled
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