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MFI: Multiport Fuel Injection
EVAP: Evaporative Emission
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Scheme 250
- Disconnect the ventilation hose from the positive crankcase ventilation (PCV) valve. Remove the PCV valve from the rocker cover and reconnect it to the ventilation hose.
- Run the engine at idle and put a finger on the open end of the PCV valve and make sure that intake manifold vacuum can be felt. NOTE: The plunger inside the PCV valve will move back and forth.
- If vacuum is not felt, clean the PCV valve and ventilation hose in cleaning solvent, or replace if necessary.
Scheme 251
- Remove the PCV valve.
- Insert a thin stick (A) into the PCV valve (B) from the threaded side to check that the plunger moves.
- If the plunger does not move, the PCV valve is clogged. Clean it or replace.
DESCRIPTION
On-Board Refueling Vapor Recovery (ORVR) system is designed to prevent fuel tank vapor (HC) emissions during refueling at the gas station.
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. According to this purge process, the charcoal canister is purged and recovers its absorbing capability.
Scheme 252
Evaporative Emission Control System prevents fuel vapor stored in fuel tank from draining into the atmosphere.
When the fuel evaporates in the fuel tank, the vapor passes through vent hoses or tubes to EVAP. canister filled with charcoal and the EVAP. canister temporarily holds it with charcoal. If ECM wants to draw the gathered vapor into the combustion chambers during certain operating conditions, it will make vacuum in intake manifold to move it.
Scheme 253
A ratchet tightening device on the threaded fuel filler cap reduces the chances of incorrect installation, which would seal the fuel filler. After the gasket on the fuel filler cap and the filler neck flange contact each other, the ratchet produces a loud clicking noise indicating the seal has been set.
Scheme 254
Exhaust emissions (CO, HC, NOx) are controlled by a combination of engine modifications and the addition of special control components.
Modifications to the combustion chamber, intake manifold, camshaft and ignition system form the basic control system.
These items have been integrated into a highly effective system which controls exhaust emissions while maintaining good driveability and fuel economy.
The CVVT (Continuously Variable Valve Timing) which is installed on the exhaust camshaft, controls intake valve open and close timing in order to improve engine performance.
The intake valve timing is optimized by CVVT system depending on engine RPM.
This CVVT system improves fuel efficiency and reduces NOx emissions at all levels of engine speed, vehicle speed, and engine load by EGR effect because of valve over-lap optimization.
The CVVT changes the phase of the intake camshaft via oil pressure.
It changes the intake valve timing continuously.
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- The CVVT system makes continuous intake valve timing changes based on operating conditions.
- Intake valve timing is optimized to allow the engine to produce maximum power.
- Cam angle is advanced to obtain the EGR effect and reduce pumping loss. The intake valve is closed quickly to reduce the entry of the air/fuel mixture into the intake port and improve the changing effect.
- Reduces the cam advance at idle, stabilizes combustion, and reduces engine speed.
- If a malfunction occurs, the CVVT system control is disabled and the valve timing is fixed at the fully retarded position.
- The previous figure shows the relative operation structures of the housing vane to the rotor vane.
- If the CVVT is held a certain control angle, to hold this state, oil is replenished as much as oil leaks from the oil pump.
The OCV (Oil-flow Control Valve) spool location at this time is as follows.
Oil pump --> Advance oil chamber (Little by little open the inflow side to the advance oil chamber) --> Almost close the drain side
Be sure there might be a difference in the position according to the engine running state (RPM, oil temperature, and oil pressure).