| VELOSTER(FS) >2013 > G 1.6 T-GDI > Emission Control System > Evaporative Emission Control System>Schematic Diagrams |
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Canister
The Canister is filled
with charcoal and absorbs evaporated fuel vapor from the fuel tank. The
gathered fuel vapor in canister is drawn into the intake manifold by the
ECM/PCM when appropriate conditions are set.
Purge Control Solenoid Valve (PCSV)
The Purge Control
Solenoid Valve (PCSV) is installed in the passage connecting the canister
to the intake manifold. It is a duty type solenoid valve and is operated
by ECM/PCM signal.
To draw the absorbed
vapor into the intake manifold, the ECM/PCM will open the PCSV, otherwise
the passage remains closed.
Fuel Filler Cap
A ratchet tightening
device in the threaded fuel filler cap reduces the chances of incorrect
installation, when sealing the fuel filler. After the gasket on the fuel
filler cap and the fill neck flange make contact, the ratchet produces a
loud clicking noise indicating the seal has been set.
Fuel Tank Pressure Sensor (FTPS)
The Fuel Tank Pressure
Sensor (FTPS) is an integral part of the monitoring system. The FTPS
checks Purge Control Solenoid Valve (PCSV) operation and leaks in the
Evaporative Emission Control System by monitoring pressure and vacuum
level in the fuel tank during PCSV operating cycles.
Canister Close Valve (CCV)
The Canister Close Valve
(CCV) is located between the canister and the fuel tank air filter. It
closes off the air inlet to the canister for the Evaporative Emissions
System and also prevents fuel vapors from escaping from the Canister when
the vehicle is not operating.
Evaporative System Monitoring
The Evaporative Emission
Control Monitoring System monitors fuel vapor generation, evacuation, and
a leakage check step. At first, the OBD-II system checks if vapor
generation due to fuel temperature is small enough to start monitoring.
Then it evacuates the evaporative system by means of PCSV with ramp in
order to maintain a certain vacuum level. The final step is to check if
there is vacuum loss by any leakage of the system.
Vapor Generation Checking
During the stabilization
period, the PCSV and the CCV are closed. The system pressure is measured
as starting pressure (DP_A). After a certain defined period (T1), the
system pressure (DP_B) is measured again and the difference from the
starting pressure is calculated. If this difference (DP_B - DP_A) is
bigger than the threshold, there should be excessive vapor pressure and
the monitor is aborted for next check. On the contrary, if the difference
is lower than the negative threshold, the PCSV is regarded as having a
malfunction such as clogged at open position.
Large EVAP Leak Detection
The PCSV is opened with
a certain ramp for the pressure to reach down to a certain level. If the
pressure can’t be lowered below a threshold, the system is regarded as
having a fuel cap-open or having a large leak.
Leaking Checking
The PCSV is closed and
the system waits for a period to get stabilized pressure. During checking
period (T2), the system measures the beginning and the end of the system
pressure (DP_C, DP_D). The diagnosis value is the pressure difference
corrected by the natural vapor generation (DP_B - DP_A) rate from the
vapor generation check step.
Evaporative System Monitoring
Evaporative And ORVR Emission Control
System
This system consists of
a fill vent valve, fuel shut-off valve, fuel cut valve (for roll over),
two way valve (pressure/vacuum relief), fuel liquid/vapor separator which
is installed beside the filler pipe, charcoal canister which is mounted
under the rear floor LH side member and protector, tubes and miscellaneous
connections.
While refueling, ambient
air is drawn into the filler pipe so as not to emit fuel vapors in the
air. The fuel vapor in the tank is then forced to flow into the canister
via the fill vent valve. The fuel liquid/vapor separator isolates liquid
fuel and passes the pure vapor to the charcoal canister.
While the engine is
operating, the trapped vapor in the canister is drawn into the intake
manifold and then into the engine combustion chamber. Using this purge
process, the charcoal canister is purged and recovers its absorbing
capability.
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