1GR-FE ENGINE

The configuration of the engine control system is as shown in the following chart.

Cranks position sensor and VVT Sensor

1. General

   
   

   • Pick up coil type crank position sensor is used. 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 missing teeth are used to determine the top-dead-center.

   • MRE (Magnetic Resistance Element) type VVT sensor is used. To detect the camshaft position, a timing rotor that is secured to the camshaft in front of the VVT controller is used to generate 3 (3 Hi output, 3 Lo output) for every 2 revolutions of the crankshaft.

     

     *1	Crank Position Sensor	*2	Timing Rotor
     *3	VVT Sensor (For Bank 2, Intake)	*4	VVT Sensor (For Bank 2, Exhaust)
     *a	Front	-	-

     Figure 1. Sensor Output Waveforms

     

     *a	VVT Sensor Signal
     *b	Crank Position Sensor Signal
     *c	2 Teeth Missing

2. MRE Type VVT Sensor

   
   

   • The MRE type VVT sensor consists of an MRE, a magnet and a sensor. The direction of the magnetic field changes due to the different shapes (protruded and non-protruded 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 Hi or Lo. The ECM detects the camshaft position based on this output voltage.

   • The differences between the MRE type VVT sensor and the pickup coil type VVT sensor used on the conventional model are as follows.

     Item	Sensor Type
     	MRE	Pick up Coil
     Signal Output	Constant digital output starts from low engine speeds	Analog output changes with the engine speed
     Camshaft Position Detection	Detection based on the waveforms output throughout the timing rotor speed range	Detection based on the waveforms output as the protruded portion of the timing rotor passes

     Figure 2. Wiring Diagram

     

     *1	Timing Rotor
     *2	VVT Sensor

     Figure 3. MRE Type and Pickup Coil Type Output Waveform Image Comparison

     

Accelerator Pedal Position Sensor

1. The no-contact type accelerator pedal position sensor 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 that occur in the magnetic flux into electrical signals, and outputs them in the form of accelerator pedal position signals to the ECM.

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

   

   *1	Hall IC	*2	Magnetic Yoke
   *3	Accelerator Pedal Arm	-	-

   

Throttle Position Sensor

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

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 main and sub signals. The Hall IC converts the throttle valve opening angle into two electrical signals that have differing characteristics and outputs them to the ECM.

   

   *1	Magnet	*2	Hall IC
   *a	Cross Section	-	-

   

Knock Sensor (Flat Type)

1. General

   
   

   • In the conventional type knock sensor (resonant type), a vibration plate, which has the same resonance point as the knocking frequency of the engine, is built in and can detect the vibration in this frequency band.

   • On the other hand, a flat type knock sensor (non-resonant type) has the ability to detect vibration in a wider frequency band from approximately 6 kHz to 15 kHz, and has the following features:

   
   

   • The engine knocking frequency will change slightly depending on the engine speed. The flat type knock sensor can detect vibration even when the engine knocking frequency is changed. Thus the vibration detection ability is increased compared to the conventional type knock sensor, and a more precise ignition timing control is possible.

     

2. Construction

   
   

   • The flat type knock sensor is installed on the engine through the stud bolt installed on the cylinder block. For this reason, a hole for the stud bolt is running through in the center of the sensor.

   • Inside of the sensor, a steel weight is located on the upper portion and a piezoelectric element is located under the weight through the insulator.

   • The open/short circuit detection resistor is integrated.

     

     *A	Flat Type Knock Sensor (Non-resonant Type)	*B	Conventional Type Knock Sensor (Resonant Type)
     *1	Steel Weight	*2	Insulator
     *3	Piezoelectric Element	*4	Open/Short Circuit Detection Resistor
     *5	Vibration Plate	-	-

3. Operation

   
   

   • The knocking vibration is transmitted to the steel weight and its inertia applies pressure to the piezoelectric element. This action generates electromotive force.

     

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

4. Open/Short Circuit Detection Resistor

   
   

   • While the engine switch is on (IG), the open/short circuit detection resistor in the knock sensor and the resistor in the ECM keep the voltage at the terminal KNK1 of engine constant.

   • An Integrated Circuit (IC) in the ECM is always monitoring the voltage of the terminal KNK1. If the open/short circuit occurs between the knock sensor and the ECM, the voltage of the terminal KNK1 changes and the ECM detects the open/short circuit and stores Diagnostic Trouble Code (DTC).

     

     *1	Piezoelectric Element
     *2	Knock Sensor (Bank 1, Sensor 1)
     *3	Open/Short Circuit Detection Resistor

     Tech Tips

     These knock sensors are mounted in specific directions at specific angles. To prevent the right and left bank wiring connectors from being interchanged, be sure to install each sensor in its prescribed direction. For details, refer to the Repair Manual.

Air-fuel Ratio Sensor and Oxygen Sensor

1. General

   
   

   • The oxygen sensor and the air-fuel ratio sensor differ in output characteristics.

   • The output voltage of the oxygen sensor changes in accordance with the oxygen concentration in the exhaust gas. The ECM uses this output voltage to determine whether the present air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio.

   • Approximately 0.4 V is constantly applied to the air-fuel ratio sensor, which outputs an amperage that varies in accordance with the oxygen concentration in the exhaust gas. The ECM converts the changes in the output amperage into voltage in order to linearly detect the present air-fuel ratio.

     

     *: This calculation value is used internally in the ECM, and is not an ECM terminal voltage.

2. Construction

   
   

   • The basic construction of the oxygen sensor and the air-fuel ratio sensor is the same. However, they are divided into the cup type and the planar type, according to the different types of heater construction that are used.

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

   • The planar type sensor uses alumina, which excels in heat conductivity and insulation, to integrate a sensor element with the heater, thus improving the warm-up performance of the sensor.

     

     *A	Air-fuel Ratio Sensor (Planar Type)	*B	Oxygen Sensor (Cup Type)
     *1	Dilation Layer	*2	Alumina
     *3	Platinum Electrode	*4	Sensor Element (Zirconia)
     *5	Heater	*6	Atmospheric

     The illustrations above are intended to show the differences in the basic construction between the cup type sensor and the planner type sensor, so the illustrated sensor shapes may differ from the actual ones.

Control

1. General

   
   

   • The ETCS-i consists of the following functions:

   
   

   • Normal Throttle Control (Non-linear Control)

   • Idle Speed Control (ISC)

   • Cruise Control*

   
   

   • *: Models with cruise control system

2. Normal Throttle Control (Non-linear Control)

   
   

   1. General

   
   

   • Controls the throttle to an optimal throttle valve angle that is appropriate for the driving condition such as the amount of the accelerator pedal effort and the engine speed in order to realize excellent throttle control and comfort in all operating ranges.

     Figure 5. Conceptual Diagrams of Engine Control during Acceleration and Deceleration

     

   2. 2nd Start Control (Models with Automatic Transmission)

   
   

   • In situations in which low-μ (low friction) road surface conditions can be anticipated, such as when driving in the snow, the rate of throttle valve opening can be controlled to help vehicle stability while driving on the slippery surface. This is accomplished by turning on 2nd start control. Pressing the 2nd side of the pattern select switch activates this control. This control modifies the relationship and reaction of the throttle to the accelerator pedal, and assists the driver by reducing the engine output from that of a normal level.

3. Idle Speed Control

   
   

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

4. Cruise Control*

   
   

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

   
   

   • *: Models with cruise control system

Operation

1. Advance

   
   

   • When the camshaft timing oil control valve is positioned as illustrated below by the advance signals from the ECM, the resultant oil pressure is applied to the timing advance side vane chamber to rotate the camshaft in the timing advance direction.

     Figure 8. Intake Side

     

     *1	Vane Sub-assembly	*2	ECM
     *3	Camshaft Timing Oil Control Valve (Intake)	-	-
     *a	Rotation Direction	*b	Oil Pressure
     *c	In	*d	Drain

     Figure 9. Exhaust Side

     

     *1	Vane Sub-assembly	*2	ECM
     *3	Camshaft Timing Oil Control Valve (Exhaust)	-	-
     *a	Rotation Direction	*b	Drain
     *c	In	*d	Oil Pressure

2. Retard

   
   

   • When the camshaft timing oil control valve is positioned as illustrated below by the retard signals from the ECM, the resultant oil pressure is applied to the timing retard side vane chamber to rotate the camshaft in the timing retard direction.

     Figure 10. Intake Side

     

     *1	Vane Sub-assembly	*2	ECM
     *3	Camshaft Timing Oil Control Valve (Intake)	-	-
     *a	Rotation Direction	*b	Drain
     *c	In	*d	Oil Pressure

     Figure 11. Exhaust Side

     

     *1	Vane Sub-assembly	*2	ECM
     *3	Camshaft Timing Oil Control Valve (Exhaust)	-	-
     *a	Rotation Direction	*b	Oil Pressure
     *c	In	*d	Drain

3. Hold

   
   

   • After reaching the target timing, the engine valve timing is maintained by keeping the camshaft timing oil control valve in the neutral position unless the engine operating conditions change.

     This maintains the engine valve timing at the desired target position by preventing the engine oil from running out of the oil control valve.

Construction and Operation

1. Air Pump

   
   

   • Each air pump consists of a DC motor, an impeller and an air filter.

   • The DC motor is controlled by the air injection driver in accordance with signals from the ECM. The motor supplies air into an air switching valve through the impeller.

   • The air filter is maintenance-free.

   
   
   • 

     *1	Air Pump	*2	Heater
     *3	Impeller	*4	DC Motor
     *5	Air Filter	-	-
     *a	Air In	*b	Air Out
     *c	Cross Section	-	-

2. Air Switching Valve

   
   

   • The air switching valves consist of a valve that switches the air flow and a reed valve that restricts the exhaust flow to one direction.

   • The air switching valves are solenoid valves that are actuated by the ECM and air injection control driver.

   • An air pressure sensor is built into the corresponding air switching valve.

   • The structure and function of the air switching valves for bank 1 and bank 2 are basically the same.

     

     *1	Air Switching Valve (Bank 2)	*2	Air Switching Valve (Bank 1)
     *3	Air Pressure Sensor	*4	Valve
     *5	Solenoid Coil	-	-
     *a	Air In	*b	Air Out
     *c	Cross Section (Bank 1)	-	-

3. Air Pressure Sensor

   
   

   • The air pressure sensor consists of a semiconductor, which has a silicon chip that changes its electrical resistance when pressure is applied to it. The sensor converts the pressure into an electrical signal, and sends it to the ECM in an amplified form.

   • The air pressure sensors for bank 1 and bank 2 have the same basic structure and function.

     

   • The ECM detects operation of the air injection system based on signals from the air pressure sensor as follows:

   
   

   1. When the air pump is on and the air switching valve is closed, the pressure is stable.

   2. When the air pump is on and the air switching valve is open, the pressure drops slightly and becomes unstable because of exhaust pulses.

   3. When the air pump is off and the air switching valve is closed, the pressure remains at atmospheric pressure.

   4. When the air pump is off and the air switching valve is open, the pressure drops below atmospheric pressure and becomes unstable because of exhaust pulses.

      

4. Air Injection Control Driver

   
   

   • A semiconductor type air injection control driver is used. Activated by the ECM, this driver actuates the air pump and the air switching valve.

   • The air injection control driver also detects failures in the input and output circuits of the air injection driver and transmits the failure status to the ECM via duty cycle signals.

   • The following system chart shows bank 1 (left bank).

     

     DI Terminal Output

     Condition	AIRP	AIRV	Output (Duty Cycle Signal)
     Open circuit in line between AIDI and DI terminals.	-	-
     Failure in line between ECM terminals and air injection control driver.	-	-
     Output failure at air injection control driver. (Failure in air pump actuation circuit)	-	-	*1 200 ms *2 Duty 20%
     Output failure at air injection control driver. (Failure in air switching valve actuation circuit)	-	-	*1 Duty 40%
     Overheat failure of air injection control driver.	-	-	*1 Duty 60%
     Normal	On	On	*1 Duty 80%
     	Off	Off
     	On	Off
     	Off	On

Operation

1. As indicated in the timing chart below, when the ECM detects an STSW signal (start signal) from the main body ECU, it outputs a STAR signal (starter relay drive signal) through the starter cut relay to the starter relay and actuates the starter. The ECM also outputs an ACCR signal (ACC cut request signal) to the main body ECU. Thus, the main body ECU will not energize the ACC relay.

2. After the starter operates and the engine speed becomes higher than approximately 500 rpm, the ECM determines that the engine has started and stops the output of the STAR signal to the starter relay and the output of ACCR signal to the main body ECU. Thus, the starter operation stops and the main body ECU energizes the ACC relay.

3. If the engine has any failure and does not start, the starter operates as long as its maximum continuous operation time and stops automatically. The maximum continuous operation time is approximately 2 seconds through 25 seconds depending on the water temperature condition. When the engine coolant temperature is extremely low, the time is approximately 25 seconds and when the engine is warmed up sufficiently, the time is approximately 2 seconds.

4. This system cuts off the current that powers the accessories while the engine is cranking to prevent the accessory illumination from operating intermittently due to the unstable voltage that is associated with the cranking of the engine.

5. This system has following protection features:

   
   

   • While the engine is running normally, the starter does not operate.

   • Even if the driver keeps pressing the engine switch, the ECM stops the output of the STAR and ACCR signals when the engine speed becomes higher than 1200 rpm. Thus, the starter operation stops and the main body ECU energize the ACC relay.

   • In case the driver keeps pressing the engine switch and the engine does not start, the ECM stops the output of the STAR and ACCR signals after 30 seconds have elapsed. Thus, the starter operation stops and the main body ECU energize the ACC relay.

   • In case the ECM cannot detect an engine speed signal while the starter is operating, it will immediately stop the output of the STAR and ACCR signals. Thus, the starter operation stops and the main body ECU energize the ACC relay.

     Figure 15. Timing Chart