44 ENGINE 5S FE ENGINE ENGINE CONTROL SYSTEM 1. General Basic functions of the engine control system of the new 5S FE engine for the new Camry are the same as those in the 5S FE engine for the 90 model Celica. However, by using the 2 group type fuel injection system and knocking correction function in the ignition timing control, etc., the engine control system is matched with the 5S FE engine in the Camry. Comparison of the engine control system between the 5S FE engine in the Camry and the 5S FE engine in the Celica is as follows: System Outline for Camry A D type EFI system is used, which indirectly detects intake air volume by the manifold pressure sensor signal. (Electronic Fuel Injection) The fuel injection system is a 2 group type which injects to two cylin- EFI ders each. Page 50 The fuel injection system is a simultaneous all injection system. Cold Start Injector Control The injection duration of the cold start injector is controlled by the start injector time switch and ECU. Ignition timing is determined by the ECU based on signals from various sensors. for Celica ESA (Electronic Spark Advance) It retards ignition timing to suppress knocking if knocking occurs. Page 50 In vehicles equipped with automatic transaxle, torque control compensation during gear shifting is used to minimize the shift shock. ISC (Idle Speed Control) Page 51 Fuel Pump Control EGR Cut Off Control Air Conditioner Cut Off Control A rotary solenoid type ISC system is used, which controls the fast idle and idle speeds. Fuel pump operation is controlled by signals from the ECU based on the engine speed signal (NE). The EGR is cut off under light engine loads or low temperature conditions to maintain drivability. By controlling the air conditioner compressor in accordance with the throttle valve opening angle and the vehicle speed, drivability is maintained. When a malfunction occurs, the ECU diagnoses and memorizes the failed section. Diagnosis Page 51 A test mode function has been added. Fail Safe Page 53 When a malfunction occurs, the ECU stops or controls the engine according to the data already stored in memory.
ENGINE 5S FE ENGINE 45 2. Construction The configuration of the engine control system in the Camry is as shown in the following chart. Shaded portions differ from the Celica. For Manual Transaxle Models
46 ENGINE 5S FE ENGINE For Automatic Transaxle Models
ENGINE 5S FE ENGINE 47 3. Summary of Engine Control System The table summarizes the engine control system for the 5S FE engine. Items highlighted by control items and sensors. are changes in * Applicable only to California specification vehicles.
48 ENGINE 5S FE ENGINE 4. Engine Control System Diagram * Applicable only to California specification vehicles.
ENGINE 5S FE ENGINE 49 5. Arrangement of Engine Control System Components
50 ENGINE 5S FE ENGINE 6. Main Components of Engine Control System A knock sensor is added to the new 5S FE engine. For details about the knock sensor, see page TD 31 of Pub. No. NCF033U. 7. EFI (Electronic Fuel Injection) General The EFI system of the 5S FE engine in the Camry is basically the same in construction and operation as that of the 5S FE engine in the Celica, except for the injection patterns. The 5S FE engine in the Celica has a simultaneous type injection pattern for all the cylinders, but the 5S FE engine in the Camry has a 2 group type pattern in which each group injects fuel to two cylinders. 8. ESA (Electronic Spark Advance) General The ESA system of the 5S FE engine for the new Camry differs from that of the 5S FE engine for the Celica in terms of the roles of the ECU and igniter. For details, see the Tercel New Car Features (Pub. No. NCF071U, page 51). A knocking correction function using a knock sensor is added to the ignition timing control. For details about the knocking correction function, page TD 35 of Pub. No. NCF033U. Requirements for Ignition A : Determination of ignition timing B : Output of ignition timing signal (IGt) C : Calculation of primary current (ignition coil) energizing start timing D : Interruption of primary current for Camry for Celica ECU A, B and C A and B Igniter (C)* and D C and D * Correction of C
ENGINE 5S FE ENGINE 51 9. ISC (Idle Speed Control) General The ISC system of the 5S FE engine in the Camry is basically the same in construction and operation as that of the 5S FE engine in the 91 model Celica, except for the idling speed control method when the air conditioner switch is on. For the 5S FE engine in the Celica, the ECU operated only the ISC valve to perform idle up and provide feedback for the target idling speed, but in the 5S FE engine of the Camry, a VSV for idle up control is also added. Feedback Control During Air Conditioner Operation When the ECU receives a signal from the air conditioner amplifier, it opens the VSV to increase idle speed. At the same time, it begins feedback control at a target idle speed for air conditioner operation. Target Idling Speed Air Con Neutral Engine Speed (rpm) ditioner Start Switch Switch for Camry for Celica ON ON 850 950 OFF 700 750 OFF ON 700 OFF 600 RELEVANT SIGNALS Engine speed (NE) Coolant temperature (THW) Throttle position (IDL) Vehicle speed (SPD) Air conditioner switch (A/C) NOTE: At engine adjustment time, etc., with the vehicle stopped, confirm the idling speed by connecting terminals TE1 and E 1 in the check connector or TDCL with the throttle valve fully closed. Under the above conditions, air conditioner operation is cut off and only idle up occurs.
52 ENGINE 5S FE ENGINE 10.Diagnosis In the new 5S FE engine, a test mode function is added to the diagnostic system (normal mode) for the purpose of detecting malfunctions such as poor contact between the connector terminals and momentary wire disconnection, which are difficult to detect in the normal mode. This new function improves the ability of the self diagnostic system and simplifies troubleshooting. For details, see the Cressida New Car Features (Pub. No. NCF044U). Diagnostic Items Code No. Item Diagnostic* 1 Mode Normal Test 12 RPM 13 RPM 14 16 21 22 24 25 26 27 31 Ignition ECT Control Main Oxygen Water Temp. Intake Air Temp. Air Fuel Ratio Lean Malfunction Air Fuel Ratio Rich Malfunction Sub Oxygen Manifold Pressure Diagnosis No NE signal to ECU within 2 seconds after engine is cranked. No G signal to ECU for 3 seconds when the engine speed is between 600 rpm and 4000 rpm. No NE signal to ECU when the engine speed is above 1500 rpm. No G signal to ECU while NE signal is input 4 times to ECU when engine speed is between 500 rpm and 4000 rpm. Malfunction Stored in Memory No IGF signal to ECU 4 times in succession. ECT control program faulty. * 2 During air fuel ratio feedback correction, output voltage of main oxygen sensor remains between 0.35 V and 0.7 V continuously for a certain period. Open or short circuit in water temp. sensor signal (THW). Open or short circuit in intake air temp. sensor signal (THA). * 3 * 3 Open or short circuit in main oxygen sensor signal (OX 1 ). * 4 * 4 revolutions for each cylinder during idle switch on When marked variation is detected in engine and feedback condition. * 4 * 4 Open or short circuit in sub oxygen sensor signal (OX 2 ). Open or short circuit in manifold pressure sensor signal (PIM).
ENGINE 5S FE ENGINE 53 Code No. 41 42 43 52 71 51 Item Throttle Position Diagnostic* 1 Mode Normal Test * 2 No. 1 Speed X X Starter Knock EGR System Malfunction Switch Condition X Diagnosis Open or short circuit in throttle position sensor signal (V TA ). No SPD signal to ECU for 8 seconds when vehicle is running. No SPD signal input to ECU after ignition switch is turned on. No STA signal input to ECU after ignition switch is turned on. Malfunction Stored in Memory Open or short circuit in knock sensor signal (KNK). * 4 * 4 EGR operation. EGR gas temp. below a predetermined level during Open circuit in EGR gas temp. sensor signal (THG). X No IDL signal or No NSW signal or A/C signal to ECU during diagnosis code check for test mode. No No No * 1 : mark in the diagnostic mode column indicates that the CHECK ENGINE lamp will light up when a diagnosis is conducted and a malfunction is detected. X mark indicates that the lamp will not light even if a malfunction is detected during a diagnosis. mark indicates that a diagnosis is not performed for that item. * 2 : In the normal mode, when a malfunction occurs in code Nos. 24 and 41, the CHECK ENGINE lamp lights up only in California specification vehicles. * 3 : When a malfunction occurs, only code No. 25 is stored. * 4 : This diagnosis occurs only in California specification vehicles. If a malfunction occurs involving a lean or rich air fuel ratio, code Nos. 25 and 26 are stored simultaneously in the ECU. 11.Fail Safe The fail safe function of the previous 5S FE engine is also used in the 5S FE engine in the new Camry, together with the following additional functions. Knock or Knock Control System Malfunction If the knock sensor circuit becomes open or shorted, or if trouble develops in the knock control system in the ECU, the ECU corrects ignition timing to the knock prevention correction maximum retard condition to prevent knocking. ECT Control System Malfunction If trouble occurs in the ECT control system in the ECU, the ECT does not operate properly. Torque control correction by the ESA is prohibited.