SFI SYSTEM

Variable Valve Timing Control

1. A variable valve timing mechanism is used for the camshaft timing intake gear assemblies and the camshaft timing exhaust gear assemblies. It continuously alters the camshaft phase and improves torque and fuel efficiency by enabling optimal valve timing according to the vehicle's driving or running state.

2. In addition to advanced and retarded oil passages inside the camshaft timing gear assembly, a detent oil passage has been installed, making intermediate locking possible.

3. A thin cam timing oil control valve assembly has been installed from the front surface side of the timing chain cover to make the variable valve timing mechanism more compact.

4. The cam timing oil control valve assembly operates by signals from the ECM, controlling the position of the spool valve and supplying engine oil to the advance hydraulic chamber and retard hydraulic chamber of the camshaft timing gear assembly.

5. The camshaft timing gear assembly built into the chain cover is non-destructive.

   

   Text in Illustration

   *1	Retard Hydraulic Chamber	*2	Advance Hydraulic Chamber
   *3	Camshaft Timing Gear Assembly	*4	Advance Check Valve
   *5	Detent Port	*6	Spool Valve
   *7	Cam Timing Oil Control Valve Assembly	*8	ECM
   *9	Inlet Check Valve	*10	Oil Pump
   *11	Camshaft Cap	*12	Lock Pin
   *13	Detent Valve	*14	Retard Check Valve
   *a	from Oil Strainer Sub-assembly	-	-

   

6. The Variable Valve Timing Control delivers excellent benefits in the different vehicle states as shown in the table below:

   Operation State	Objective		Effect
   During Idling	*1 TDC *2 Earliest Timing (EX) *3 Latest Timing (IN) *4 BDC	Eliminating overlap reduces blow back to the intake side.	Stabilized idling engine speed Better fuel economy
   At Light Load	*1 To Advance Side (EX) *2 TDC *3 To Retard Side (IN) *4 BDC	Eliminating overlap to reduce blow back to the intake side.	Ensured engine stability
   At Medium Load	*1 to Advance Side (IN) *2 TDC *3 to Retard Side (EX) *4 BDC	Increasing overlap increases internal EGR, reducing pumping losses.	Better fuel economy Improved emission control
   In Low to Medium Speed Range with Heavy Load	*1 TDC *2 to Retard Side (EX) *3 to Advance Side (IN) *4 BDC	Advancing the intake valve closing timing improves volumetric efficiency.	Improved torque in low to medium speed ranges
   In High Speed Range with Heavy Load	*1 TDC *2 to Retard Side (IN) *3 to Advance Side (EX) *4 BDC	Retarding the intake valve closing timing improves volumetric efficiency.	Improved output
   At Low Temperatures	*1 TDC *2 Earliest Timing (EX) *3 Latest Timing (IN) *4 BDC	Eliminating overlap to reduce blow back to the intake side stabilizes the idling speed at fast idle.	Stabilized fast idle engine speed Better fuel economy
   Upon Starting Stopping Engine	*1 TDC *2 Earliest Timing (EX) *3 Latest Timing (IN) *4 BDC	Eliminating overlap minimizes blow back to the intake side.	Improved startability

Electronic Throttle Control System-intelligent (ETCS-i)

1. The ETCS-i is used, providing excellent throttle control in all the operating ranges. The accelerator cable has been discontinued, and an accelerator pedal sensor assembly has been provided on the accelerator pedal.

2. In the conventional throttle body, the throttle valve opening is determined by the amount of the accelerator pedal effort. In contrast, the ETCS-i uses the ECM to calculate the optimal throttle valve opening that is appropriate for the respective driving condition and uses a throttle control motor to control the opening.

3. The ETCS-i controls the idle speed, Traction Control (TRC), Vehicle Stability Control (VSC) system, cruise control system*.

   
   

   • *: Models with cruise control system

4. In case of an abnormal condition, this system switches to the limp mode.

   

Crankshaft Position Sensor

1. A pick-up coil type crank position sensor is used. The timing rotor of the crankshaft consists of 30 teeth, with 2 and 4 teeth missing. The crank position sensor outputs the crankshaft rotation signals every 10°.

   

Camshaft Position Sensor

1. Giant Magneto Resistance (GMR) Element type camshaft position sensors (intake and exhaust) are used. To detect each camshaft (intake) position, a timing rotor that is secured to the camshaft (intake) in front of the camshaft timing gear assembly is used to generate 6 (3 high output, 3 low output) pulses for every 2 revolutions of the crankshaft. To detect each camshaft (exhaust) position, a timing rotor that is secured to the camshaft (exhaust) in front of the camshaft timing gear assembly is used to generate 4 (2 high output, 2 low output) pulses for every 2 revolutions of the crankshaft.

   

2. GMR type camshaft position sensor consists of an GMR, a magnet and a sensor. The direction of the magnetic field changes due to the profile (protruding and non-protruding portions) of the timing rotor, which passes by the sensor. As a result, the resistance of the GMR changes, and the output voltage to the ECM changes to high or low. The ECM detects the camshaft position based on this output voltage.

   

Accelerator Pedal Position Sensor

1. This non-contact type accelerator pedal sensor assembly uses a Hall IC, which is mounted on the accelerator pedal arm.

2. A magnetic yoke is mounted at the base of the accelerator pedal arm. This yoke rotates around the Hall IC in accordance with the amount of effort that is applied to the accelerator pedal. The Hall IC converts the changes in the magnetic flux that occur into electrical signals, and outputs them in the form of accelerator pedal position signals to the ECM.

3. The Hall IC contains 2 circuits, 1 for the VPA signal and 1 for the VPA2 signal. The Hall IC converts the accelerator pedal position (angle) into electric signals that have differing characteristics and outputs them to the ECM.

   

Throttle Position Sensor

1. This non-contact type throttle position sensor uses a Hall IC, which is mounted on the throttle body with motor assembly.

2. The Hall IC is surrounded by a magnetic yoke. The Hall IC converts the changes that occur in the magnetic flux into electrical signals, and outputs them in the form of throttle valve position signals to the ECM.

3. The Hall IC contains circuits for the VTA1 and VTA2 signals. The Hall IC converts the throttle valve opening angle into electric signals that have differing characteristics, and outputs them to the ECM.

   

Knock Control Sensor (Flat Type)

1. A flat type knock control sensor (non-resonant type) is used.

2. Reliability has been ensured by attaching one each to the left and right cylinder blocks.

3. Vibrations caused by knocking are transmitted to the steel weight. The inertia of this weight applies pressure to the piezoelectric element. This action generates electromotive force.

4. Voltage is output almost uniformly across all frequency bands, and the ECM detects the targeted generation frequency to determine knocking.

   

   Text in Illustration

   *1	Steel Weight	*2	Piezoelectric Element
   *3	Base	-	-
   *a	Inertia	*b	to Cylinder Block

Air Fuel Ratio Sensor and Oxygen Sensor

1. A planar type (wide range air fuel ratio sensor) and a cup type oxygen sensor are used. The basic construction of the oxygen sensor and the (wide range air fuel ratio sensor) is the same. However, they are divided into the cup type and the planar type in accordance with the different types of heater construction used.

2. The planar type air fuel ratio sensor uses alumina, which excels in heat conductivity and electrical insulation, to integrate the sensor element with a heater, thus improving the warmup performance of the sensor.

3. The cup type oxygen sensor contains a sensor element that surrounds the heater.

   

   Text in Illustration

   *A	Planar Type Wide Range Air Fuel Ratio Sensor	*B	Cup Type Oxygen Sensor
   *1	Diffusion Resistance Layer	*2	Alumina
   *3	Platinum Electrode	*4	Sensor Element (Zirconia)
   *5	Heater	*6	Atmosphere

4. As illustrated below, the conventional oxygen sensor is characterized by a sudden change in its output voltage at the threshold of the stoichiometric air fuel ratio (14.7:1). In contrast, the air fuel ratio sensor data is approximately proportionate to the existing air fuel ratio. The air fuel ratio sensor converts the oxygen density to current and sends it to the ECM. As a result, the detection precision of the air fuel ratio has been improved. The air fuel ratio sensor data can be viewed using a Global TechStream (GTS).

   

Oil Control Solenoid

1. The position of the spool valve is controlled by a duty signal from the ECM to maintain constant optimal valve timing. When the engine is stopped, the spool valve is put into intermediate locking position on the intake side by spring power, and maximum advance state on the exhaust side, to prepare for the next activation.

   

   Text in Illustration

   *1	Cam Timing Oil Control Valve Assembly	*2	Spool Valve
   *3	Spring	-	-
   *a	to Advance Hydraulic Chamber	*b	to Check Valve
   *c	to Retard Hydraulic Chamber	*d	Oil Pressure
   *e	to Detent Valve	-	-

Ignition Coil Assembly

1. The Direct Ignition System (DIS) provides 4 ignition coil assemblies, one for each cylinder. The spark plug caps, which provide contact to spark plugs, are integrated with the ignition coil assembly. Also, an igniter is enclosed to simplify the system.

   

   Text in Illustration

   *1	Igniter	*2	Primary Coil
   *3	Secondary Coil	*4	Plug Cap
   *5	Iron Core	-	-
   *a	Cross Section	-	-

Spark Plug

1. Long-reach type spark plugs are used. This type of spark plugs allows the area of the cylinder head sub-assembly that receives the spark plugs to be made thick. Thus, the water jacket can be extended near the combustion chamber, which contributes to cooling performance.

2. The triple ground electrode type iridium-tipped spark plugs are used to achieve a 60000 miles (96000 km) maintenance interval. By making the center electrode of iridium, it is possible to achieve superior ignition performance and durability when compared to platinum-tipped spark plugs. Furthermore, 2 ground electrodes have been added to further enhance ignitability, wear resistance, and fouling resistance.

   

   Text in Illustration

   *1	Iridium Tip	*2	Platinum Tip
   *a	Long-reach	-	-

Fuel Pump Control

1. In this vehicle, there are 2 types of fuel pump controls. The fuel pump is controlled to an optimum speed to match the engine operating conditions, and the fuel pump operation is stopped when the SRS airbags deploy.

2. The ECM transmits a fuel pump operation request signal to the fuel pump control ECU that corresponds to the engine operating conditions. The fuel pump control ECU receives this request signal and controls the speed of the fuel pump. As a result, under light engine loads, fuel pump speed is kept low to reduce electric power loss.

3. A fuel cut control is used to stop the fuel pump when any of the SRS airbags deploys. In this control, if an airbag deployment signal from the air bag ECU assembly is detected by the ECM, the ECM will turn off the circuit opening relay. As a result, the power supply to the fuel pump control ECU assembly is stopped, causing the fuel pump to stop operating. After the fuel cut control has been activated, turning the ignition switch from OFF to ON cancels the fuel cut control, and the engine can be restarted.

4. The fuel pump control ECU assembly controls fuel pump speed by receiving a duty cycle signal from the ECM.

   

Cooling Fan Control

1. In vehicles equipped with air conditioners, the ECM switches the rotation speed of the 2 cooling fan motors between the 3 states Hi, Lo, and Off according to vehicle acceleration, coolant temperature and the status of the air conditioner.

   

ETCS-i

1. The ECM drives the throttle control motor by determining the target throttle valve opening in accordance with the respective operating condition.

2. The ECM controls the throttle to an optimal throttle valve opening that is appropriate for driving conditions such as the amount of accelerator pedal effort and the engine speed, in order to achieve excellent throttle control and comfort in all operating ranges.

   

3. The ECM controls the throttle valve in order to constantly maintain an ideal idle speed.

4. As part of the TRC, the throttle valve opening angle is reduced by a demand signal sent from the skid control ECU to the ECM. This demand signal is sent if an excessive amount of slippage occurs at a drive wheel, thus ensuring vehicle stability and applying an appropriate amount of power to the road.

5. In order to bring the effectiveness of the VSC into full play, the throttle valve angle is regulated through a coordination control by the skid control ECU and the ECM.

6. The ECM directly actuates the throttle valve for operation of the cruise control.*

   
   

   • *: Models with cruise control system

Starter Control (Cranking Hold Function)*

1. When the smart key ECU assembly receives the start signal from the engine switch (push start switch), the engine startup permission signal is sent to the ECM. The ECM, which receives the engine startup permission signal, makes a determination for each requirement (whether the gear shift is in Park or Neutral, the clutch state, etc.) and sends the activation signal to the starter relay, activating the starter. At this time, the smart key ECU assembly in accordance with direction from ECM sets the ACC relay activation signal to off and prevents flickering of the gauges, clock, audio display, etc.

2. During cranking, the ECM continues to send the activation signal to the starter relay until it is detected that the engine has completely started up. Complete engine startup is determined by the ECM, and when a determination of complete engine startup is made, the ECM stops signal output to the starter relay.

3. The cranking hold time and complete startup determination count by the ECM are determined according to engine coolant temperature.

4. This system has the following protections:

   
   

   • The starter will not operate if the engine is operating normally.

   • If the engine switch (push start switch) is pushed and held, cranking will stop once the engine speed reaches a pre-determined level. This prevents the starter from over-revving.

   
   

   • *: Models with entry and start system