SFI SYSTEM DETAILS

Acoustic Control Induction System (ACIS)

1. The Acoustic Control Induction System (ACIS) uses a rotary type intake air control valve to divide the intake manifold, creating 2 stages. The intake air control valve is opened or closed to vary the effective length of the intake manifold in accordance with the engine speed and throttle valve opening angle. This increases the power output in all ranges from low to high speed.

   

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   *1	Actuator	*2	Vacuum Switching Valve Assembly
   *3	Crank Position Sensor Signal	*4	ECM
   *5	Throttle Position Sensor	*6	Intake Air Control Valve

Tumble Control System (Models with Tumble Control System)

1. The tumble control system generates tumble flow using the tumble control valves when the engine is cold. This achieves excellent combustion conditions.

2. The ECM controls the tumble control valve according to the engine coolant temperature signal.

   

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   *1	Tumble Control Valve	*2	Intake Air Control Valve Actuator
   *3	Tumble Control Valve Position Sensor	*4	ECM
   *5	E. F. I. Engine Coolant Temperature Sensor	-	-
   	Intake Air	-	-

Intake Mass Air Flow Meter Sub-assembly

1. The intake mass air flow meter sub-assembly, which is a slot-in type, allows a portion of the intake air to flow through the detection area. By directly measuring the mass and the flow rate of the intake air, the detection precision is improved and the intake air resistance is reduced.

2. This intake mass air flow meter sub-assembly has a built-in intake air temperature sensor.

   

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   *1	Platinum Hot-wire Element	*2	Temperature Sensing Element
   *3	Intake Air Temperature Sensor	-	-
   *a	A-A Cross Section	-	-
   	Air Flow	-	-

Crank Position Sensor

1. The timing rotor of the crankshaft consists of 34 teeth with 2 teeth missing. The crank position sensor outputs the crankshaft rotation signals every 10°, and the change of the signal due to the missing teeth is used to determine top-dead-center.

   

Camshaft Position Sensor

1. Magneto-Resistance Element (MRE) type camshaft position sensors (intake and exhaust) are used. To detect each camshaft position, a timing rotor that is part of the camshaft is used to generate 3 pulses for every 2 revolutions of the crankshaft.

   

2. An MRE type camshaft position sensor consists of an MRE, 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 MRE changes, and the output voltage to the ECM changes to high or low. The ECM detects the camshaft position based on this output voltage.

   

Knock Control Sensor (Flat Type)

1. In a conventional knock control sensor (resonant type), a vibration plate is built into the sensor. This plate has the same resonance point as the knocking* frequency of the engine block. This sensor can only detect vibration in this frequency band.

   *: The term "knock" or "knocking" is used in this case to describe either preignition or detonation of the air fuel mixture in the combustion chamber. This preignition or detonation refers to the air fuel mixture being ignited earlier than is advantageous. This use of "knock" or "knocking" is not primarily used to refer to a loud mechanical noise that may be produced by an engine. A flat type knock control sensor (non-resonant type) has the ability to detect vibration in a wider frequency band (from about 6 to 15 kHz). It has the following features:

   
   

   • A flat type knock control sensor is installed to an engine by placing it over the stud bolt installed on the cylinder block sub-assembly. For this reason, a hole for the stud bolt exists in the center of the sensor.

   • In the sensor, a steel weight is located in the upper portion. An insulator is located between the weight and a piezoelectric element.

   • An open/short circuit detection resistor is integrated in the sensor.

2. The engine knocking frequency will vary slightly depending on the engine speed. The flat type knock control sensor can detect vibration even when the engine knocking frequency changes. Due to the use of the flat type knock control sensor, the vibration detection ability is increased compared to a conventional type knock control sensor, and more precise ignition timing control is possible.

   

3. An open/short circuit detection resistor is integrated in the sensor. When the ignition is ON, the open circuit detection resistor in the knock control sensor and the resistor in the ECM keep the voltage at terminal KNK1 constant. An Integrated Circuit (IC) in the ECM constantly monitors the voltage of terminal KNK1. If an open or short circuit occurs between the knock control sensor and the ECM, the voltage of terminal KNK1 will change and the ECM will detect this and store a Diagnostic Trouble Code (DTC).

   

4. 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.

   

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   *1	Steel Weight	*2	Inertia
   *3	Piezoelectric Element	-	-

Throttle Position Sensor

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

   
   

   • 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.

   • The Hall IC contains circuits for the main and sub signals. It converts the throttle valve opening angle into electric signals that have differing characteristics, and outputs them to the ECM.

     

     Tech Tips

     The inspection method differs from a contact type throttle position sensor because this non-contact type throttle position sensor uses a Hall IC. For details, refer to the Repair Manual.

Accelerator Pedal Position Sensor

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

   
   

   • 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.

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

     

     

     Tech Tips

     The inspection method differs from a contact type accelerator pedal position sensor because this non-contact type accelerator pedal position sensor uses a Hall IC. For details, refer to the Repair Manual.

Camshaft Timing Oil Control Valve Assembly

1. The camshaft timing oil control valve assembly controls its spool valve using duty-cycle control from the ECM. This allows hydraulic pressure to be applied to the camshaft timing gear assembly or camshaft timing exhaust gear assembly advance or retard side. When the engine is stopped, the camshaft timing oil control valve assembly (intake) will move to the retard position, and the camshaft timing oil control valve assembly (exhaust) will move to the advance position.

   

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   *1	Spring	*2	Sleeve
   *3	Drain	*4	Oil Pressure
   *5	Spool Valve	*6	Plunger
   *7	Coil	-	-
   *a	To Camshaft Timing Gear Assembly (VVT-i Controller) (Advance Side)*	*b	To Camshaft Timing Gear Assembly (VVT-i Controller) (Retard Side)*

   *: On the exhaust side oil control valve, the advance and retard sides are reversed.

Intake Air Control Valve

1. The intake air control valve is installed in the intake manifold. It opens and closes to provide 2 effective intake manifold lengths.

2. The ACIS actuator activates the intake air control valve based on signals from the ECM.

   

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   *1	VSV	*2	ACIS Actuator
   *3	Intake Air Control Valve	-	-

Tumble Control Valve (Models with Tumble Control System)

1. The tumble control valves are built into the intake manifold. The tumble control valves close when the engine is cold, generating tumble flow in the combustion chamber.

2. The actuator activates the tumble control valves based on signals from the ECM.

   

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   *1

   Intake Air Control Valve Actuator - Tumble Control Valve Position Sensor

   *2

   Tumble Control Valve

Intake Air Control Valve Actuator (Models with Tumble Control System)

1. A tumble control valve position sensor that uses a Hall IC is built into the actuator for the tumble control valves.

2. The tumble control valve position sensor detects the opening amount of the tumble control valves, and sends signals to the ECM.

   

Ignition Coil Assembly

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

   

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

Spark Plug

1. Long-reach type spark plugs are used. This type of spark plug 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. Iridium-tipped spark plugs are used to achieve a 100000 km (62140 miles) 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.

   

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   *1	Water Jacket	*2	Iridium Tip
   *3	Platinum Tip	-	-

Acoustic Control Induction System (ACIS)

1. To match the longer pulsation cycle, the ECM activates the VSV so that vacuum acts on the diaphragm chamber of the actuator. This closes the control valve. As a result, the effective length of the intake manifold is lengthened and the intake efficiency in the medium speed range is improved due to the dynamic effect of the intake air, thereby increasing the power output.

   

2. Under any condition except when the engine is running at medium speed under high load, the ECM causes the actuator to open the control valve. When the control valve is open, the effective length of the intake air surge tank is shortened and peak intake efficiency is shifted to the low-to-high engine speed range, thus providing greater output at low-to-high engine speeds.

   

Tumble Control System (Models with Tumble Control System)

1. When the engine is cold, the ECM controls the intake air control valve actuator, closing the tumble control valves to generate a strong tumble flow in the combustion chamber. As a result, even when cold, stable combustion is possible using a leaner air fuel ratio.

2. The ECU promotes rapid warming of the catalyst by retarding the ignition timing.

3. The ECM can optimize fuel economy and control exhaust emissions when cold because vacuum is generated downstream of the tumble control valves after they close, controlling the adhesion of fuel to the sides of the intake ports.

4. When the engine is warm and cold, the ECM controls the intake air control valve actuator, opening the tumble control valves completely. As a result, the intake air resistance due to the tumble control valves is minimized.

5. The tumble control valve is moved to its fully closed position during cold starting and cold running conditions to improve exhaust emissions while the engine is cold.

   

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   *1	Tumble Control Valve	-	-
   *a	Tumble Flow	-	-

Fuel Pump Control

1. The fuel pump is controlled by the ECM. Fuel pump control has a fuel cut control function. Fuel cut control stops the fuel pump when any of the SRS airbags has deployed.

   
   

   • When the ECM detects the airbag deployment signal from the airbag sensor assembly, the ECM will turn the C/OPN relay off. After fuel cut control has been activated, turning the ignition switch from off to ON cancels fuel cut control, and the engine can be restarted.

     

Cooling Fan Control System

1. For the cooling fan control system, the ECM controls the cooling fan speed in accordance with the engine coolant temperature and the air conditioner operating conditions.

   
   

   • The ECM controls the cooling fan speed based on air conditioning pressure sensor signals and engine coolant temperature sensor signals. The air conditioning pressure sensor signals are sent from the air conditioning amplifier to the ECM. This control is accomplished by operating the 2 fan motors in 2 stages at low speed (series connection) and high speed (parallel connection).

   

   

Starter Control (Cranking Hold Function) (Models with Smart Entry and Start System)

1. When the engine switch is pressed, the certification ECU (smart key ECU assembly) receives a start signal.

2. When the certification ECU (smart key ECU assembly) detects a smart signal (STSW), the certification ECU (smart key ECU assembly) outputs a starter relay drive signal (STAR). The signal goes through the park/neutral position switch assembly to the starter relay. The starter relay activates the starter assembly when it receives this signal. At this time, the certification ECU (smart key ECU assembly) turns off the ACC relay by turning off the power sent from the ACCD terminal. the ACC relay is turned off to prevent flickering of the meters, clock and audio system.

3. When communication between the certification ECU (smart key ECU assembly) and ECM stops, the certification ECU (smart key ECU assembly) uses the engine speed (NE) signal received from the ECM via a direct line to determine when to turn off the starter.

   

4. While cranking, the certification ECU (smart key ECU assembly) continues energizing the starter relay until it is determined that the engine has started. When the certification ECU (smart key ECU assembly) has judged that the engine has started, the certification ECU (smart key ECU assembly) stops energizing the starter relay.

5. If the engine does not start, the starter operates for a length of time that is based on engine coolant temperature. This can range from 25 seconds at lower temperatures to 2 seconds when the engine is at operating temperature.

   

6. This system has the following safety features:

   
   

   • While the engine is running, the starter cannot operate.

   • The starter will stop operating once the engine has started, even if the engine switch remains pushed.

   • Starter operation is limited to a maximum of 25 seconds to protect the starter motor.