ENGINE 3S GTE ENGINE DESCRIPTION ENGINE 3S GTE ENGINE

Transcription

1 39 ENGINE 3S GTE ENGINE DESCRIPTION The new MR2 has the 2.0 liter, 16 valve, DOHC 3S GTE engine with turbocharger which is used in the Celica All Trac/4WD models and has been well received. The 3S GTE engine has much greater output and torque than the 4A GZE engine used previously, providing a more comfortable drive in the MR2.

2 40 ENGINE 3S GTE ENGINE ENGINE SPECIFICATIONS AND PERFORMANCE CURVE Engine Item 3S GTE 4A GZE No. of Cyls. & Arrangement 4 Cylinder, In line Type Valve Mechanism 4 Valves, DOHC, Belt Drive Combustion Chamber Pentroof Type Manifolds Cross flow Displacement cu. in. (cc) (1998) 96.8 (1587) Bore x Stroke in. (mm) 3.39 x 3.39 (86 x 86) 3.19 x 3.03 (81 x 77) Compression Ratio 8.8 : : 1 Max. Output (SAE NET) rpm rpm Max. Torque (SAE NET) 200 ft rpm 140 ft rpm Fuel Octane Number (RON) 96 Oil Grade API SG API SF or SG

3 41 MODIFICATIONS The 3S GTE engine in the new MR2 differs from the 3S GTE engine in the 1990 model Celica in the following ways. For further details, refer to Celica New Car Features (Pub. No. NCF056U). Component Intercooler Air By Pass Valve Engine ECU Charging System Contents To suit the middle layout of the engine, the intercooler is installed to the right air inlet section which provides effective cooling. The front and rear of the turbocharger compressor wheel are connected by the air by pass valve to reduce the intake air noise occurring when the engine changes from turbocharging to deceleration. When optional ABS is installed, the control items of the EFI (Electronic Fuel Injection) and ISC (Idle Speed Control) are partially changed. When optional EHPS (Electro Hydraulic Power Steering) is installed, EHPS control is added. Air conditioner cut off control has been discontinued. If the EHPS option is installed, an alternator with output booster control function is also fitted.

4 42 ENGINE 3S GTE ENGINE INTAKE SYSTEM 1. Air to Air Intercooler Accompanying the middle layout of the engine, the position of the intercooler has been moved to the right air inlet section and the intercooler core size has changed. The cooling performance is the same as for the 3S GTE engine in the 1990 model Celica. Core Size 3S GTE engine on MR2 3S GTE engine on Celica W 7.9 in. (200 mm) 8.9 in. (225 mm) H 10.4 in. (264 mm) 9.4 in. (238 mm) D 2.5 in. (64 mm) 2.5 in. (64 mm)

5 43 2. Air By Pass Valve Even though the engine switches from turbocharging to a deceleration state, turbocharging continues briefly due to the inertia of the turbocharger turbine, so the pressure between the turbocharger and the throttle valve increases. Because the distance between the turbocharger and the throttle valve is longer in the 3S GTE engine of the MR2 than in the 1990 model Celica, iintake air noise is produced. The air by pass valve is installed to release this pressure and reduce the intake air noise. Construction The air by pass valve is opened and closed by the vacuum applied by the vacuum hose from the intake air chamber. This vacuum hose divides, one side leading to chamber A and the other leading to chamber B. However, the hose leading to chamber B has a VTV (Vacuum Transmitting Valve) installed in it to delay application of the vacuum. Operation When the engine changes from turbocharging to deceleration, a strong vacuum is applied by the vacuum hose, by the vacuum is not applied right away to the chamber linked to the VTV. Accordingly, the diaphragm is pulled toward chamber A where the vacuum is strong, thus pulling open the air by pass valve. As a result, the compressed air between the turbocharger and throttle valve flows through the air by pass valve to the upper flow side of the turbocharger.

6 44 ENGINE 3S GTE ENGINE ENGINE CONTROL SYSTEM 1. General If the ABS (Anti Lock Brake System) option is installed on the new MR2, part of the control items for EFI (Electronic Fuel Injection) and ISC (Idle Speed Control) are changed in the engine control system of the 3S GTE engine. Also, if the EHPS (Electro Hydraulic Power Steering) option is added, EHPS control is added. The following table shows the comparison between the engine control systems of the 3S GTE engine in the MR2 and in the Celica. Engine System EFI (Electronic Fuel Injection) Cold Start Injector Control ESA (Electronic Spark Advance) Fuel Judgment ISC (Idle Speed Control) T VIS (Toyota Variable Induction System) Turbocharging Pressure Control EGR Cut Off Control Oxygen Sensor Heater Control Fuel Pump Control 3S GTE of MR2 An L type EFI system is used, which directly detects the intake air volume with a vane type air flow meter. The fuel injection system is an independent injection system. ( See page 50) When coolant temperature is between 50 F and 104 F (10 C and 40 C), the injection duration of the cold start injector is controlled by the ECU. At 62.6 F (17 C) or lower, it is controlled by the start injector time switch. The ECU controls ignition timing in accordance with signals from various sensors. ECU stores two basic advance angle data according to the fuel octane rating. The ECU judges by the signal from the knock sensor whether the fuel octane rating is premium or regular. A rotary solenoid type ISC system is used, which controls the fast idle and idle speeds. ( See page 50) The intake air passages are switched according to the engine speed and fuel octane rating to increase performance in low and medium speed ranges. Suppresses turbocharging pressure to reduce knocking when regular unleaded gasoline is used. Cuts off EGR according to the engine condition to maintain drivability of the vehicle and durability of the EGR components. Maintains the temperature of the oxygen sensor at an appropriate level to increase accuracy of detection of the oxygen concentration in the exhaust gas. Fuel pump operation is controlled by signals from ECU. 3S GTE of Celica

7 45 Fuel Pump Speed Control Air Conditioner Cut Off Control EHPS* (Electro Hydraulic Power Steering Control) Diagnosis Fail Safe Under light engine loads pump speed is reduced, maintaining durability of the pump. N.A. When the engine is started at low temperatures or at low rpm, the EHPS is cut to reduce the load on the alternator, maintain engine startability and prevent engine stalling. ( See page 50) When a malfunction occurs, the ECU diagnoses and memorizes the failed section. The engine control system check 19 items for California models and 18 items for other models. When a malfunction occurs, the ECU stops or controls the engine according to the data already stored in memory. By controlling the air conditioner compressor in accordance with the throttle valve opening angle and the vehicle speed, drivability is maintained. N.A. *: Applicable only to vehicles with power steering.

8 46 ENGINE 3S GTE ENGINE 2. Construction The engine control system can be broadly divided into three groups; the sensors, ECU and actuators. Items indicated by hatching are different to the 3S GTE engine for the 1990 model Celica. * 1 : Applicable only to California specification vehicles. * 2 : Applicable only to vehicles with ABS. * 3 : Applicable only to vehicles with power steering.

9 47 3. Summary of Engine Control System The following list summarizes each system and control composing engine control system of the 3S GTE engine and types of the related sensors, ECU and others. * 1 : Applicable only to California specification vehicles. * 2 : Applicable only to vehicles with ABS. * 3 : Applicable only to vehicles with power steering.

10 48 ENGINE 3S GTE ENGINE 4. Engine Control System Diagram

11 49 5. Arrangement of Engine Control System Components

12 50 ENGINE 3S GTE ENGINE 6. EFI (Electronic Fuel Injection) EFI for the 3S GTE engine of the MR2 is the same as EFI for the 3S GTE engine in the 1990 model Celica, but when ABS (Anti Lock Brake System) is fitted as an option, a fuel cut rejection control is added. Fuel Cut Rejection Control If deceleration fuel cut control occurs during deceleration on a road surface with little traction, engine braking becomes too powerful and the tires may slip regardless of the operation of the ABS (a mechanism which prevents the wheels from locking and provides the tires with a firm grip on the road surface). CONDITIONS Fuel cut control occurs when all of the following conditions are fulfilled: Fuel cut is in operation. ABS is in operation. The engine speed is below a predetermined level. RELEVANT SIGNALS Throttle position (IDL) Stop light switch (STP) Engine speed (Ne) ABS ECU (ABS) 7. ISC (Idle Speed Control) ISC for the 3S GTE engine of the MR2 is the same as ISC for the 3S GTE engine in the 1990 model Celica, but when ABS is fitted as an option, the following control is added. When the fuel cut rejection control operates, the engine ECU fully opens the ISC valve to increase the intake air volume and reduce engine braking. 8. EHPS (Electro Hydraulic Power Steering) Control When the engine coolant temperature or the engine speed is very low, the load on the alternator is increased when the vane pump motor of the EHPS is driven. This makes it easier for poor engine startability or engine stalling to occur. To prevent this, the vane pump motor is stopped during low temperature starting or when the engine speed is extremely low. See page 70 for details on driving the vane pump motor. RELEVANT SIGNALS Water temperature (THW) Engine speed (Ne)

13 51 CHARGING SYSTEM 1. Alternator Alternator with Output Booster Control Function Vehicles with the EHPS option installed also have an alternator with an output booster control function. When the electrical load is suddenly increased, alternator output is gradually increased to prevent engine stall caused by a sudden drain on the alternator output. 1) Construction As shown below, the alternator with output booster control function has an output gradual increase control section added to the IC regulator. Alternator with Output Booster Control Function 2) System Control By gradually increasing the alternator output when the electrical load suddenly increases, the drop in the engine rpm is reduced. New Type Conventional Type