Karman Vortex Air Flow Meter L Type EFI
The Karman vortex air flow meter is used only on limited applications 7M-GTE and Lexus 1UZ-FE amp 2JZ-GE engines . The meter is smaller and lighter than the vane type meter and offers less resistance to incoming air flow. The sensor operates on the principle of measuring the vortices created as air flows past a pillar shaped vortex generator. The frequency with which these vortices are created increases in direct proportion to the amount of air flowing across the vortex generator. Vortex...
VPS Diagnosis
Check all hoses for proper connection, restrictions, and leaks. Check the VC and E2 voltages. Apply the specified pressure and read sensor voltage output. The vapor pressure sensor is calibrated for the pressures found in the EVAP system, so apply only the specified amount to prevent damaging the sensor. 1. List the different types of Pressure Sensors used on cars 2. Explain in detail the constructions and how a MAP Manifold Absolute Pressure sensor works 3. What type of voltage signal is...
Thermistors
Thermistors are variable resistors whose resistance changes in relation to temperature. Thermistors can have either a negative temperature coefficient NTC or a positive temperature coefficient PTC . A thermistor with a negative temperature coefficient will decrease in resistance as the temperature is increased. On the other hand, a thermistor with a positive temperature coefficient will increase in resistance as the temperature is increased. The thermistor has two terminals, one for power and...
Serial Data Streams
Although not required by the OBD regulation, the use of serial data accessible by special scan tools, has been introduced by some manufacturers. Serial data is electronic information about sensors, actuators, and ECM fuel spark strategy, which is accessed from a single wire coming from the ECM. The term serial data implies that the information is digitally coded and transmitted in a series of data words. The data words are decoded and displayed by a scan tool. The typical Toyota OBD serial data...
Returnless Fuel Delivery System
When the fuel pump is activated by the ECM pressurized fuel flows from the pump to the pressure regulator. At the pressure regulator excess fuel is directed to the bottom of the fuel tank and pressurized fuel is sent out of the fuel tank, through the fuel filter, pulsation damper, and into the fuel rail. When the ECM turns on the injectors fuel is delivered into the intake manifold. Fuel pressure in this system is maintained at a constant and higher pressure, 44-50 psi 301347 kPa than the...
Assignmentname Kun
1. What are the G and NE sensors 2. Explain in detail how an magnetic pick up coil type Cam or Crank sensor works. 3. Explain how the PCM ECM uses the Crankshaft position sensor signal. 4. Draw the scope pattern of both a Cam sensor and Crank sensor. 5. What is the function of a vehicle speed sensor VVS and list the three types. 6. Explain how a Pick UP Coil Variable Reluctance type VSS works 7. Explain how a Magnetic Resistance Element MRE type VSS works 8. Explain how a Reed Switch type VSS...
Vehicle Speed Sensor VSS
The ECM uses the Vehicle Speed Sensor VSS signal to modify engine functions and initiate diagnostic routines. The VSS signal originates from a sensor measuring transmission transaxle output speed or wheel speed. Different types of sensors have been used depending on models and applications. On some vehicles, the vehicle speed sensor signal is processed in the combination meter and then sent to the ECM. On some anti-lock brake system ABS equipped vehicles, the ABS computer processes the wheel...
Evaporative Emissions
Up to now, we've only discussed the creation and causes of tailpipe or exhaust emission output. However, it should be noted that hydrocarbon HC emissions come from the tailpipe, as well as other evaporative sources, like the crankcase, fuel tank and evaporative emissions recovery system. In fact, studies indicate that as much as 20 of all HC emissions from automobiles comes from the fuel tank and carburetor on carbureted vehicle, of course . Because hydrocarbon emissions are Volatile Organic...
PCV System Effects on Emissions and Driveability
Because PCV operation is factored into the proper operation of the feedback control system, problems with the PCV system may disrupt the normal air fuel ratio balance. A plugged PCV valve will prevent the normal flow of crankcase vapors into the engine and can result in a richer than normal air fuel mixture. A plugged crankcase breather hose may cause the engine to consume oil because of the increased level of crankcase vacuum. In addition, depending on the location of the fresh air breather...
Closed Loop Systems
A system that controls its output by monitoring its output is said to be a closed loop system. An example of a closed loop system is the vehicle's charging system. The voltage regulator adjusts the voltage output of the alternator by monitoring alternator voltage output. If voltage is too low, the voltage regulator will increase alternator output. Without the voltage regulator, alternator output could not be adjusted to match the electrical loads. Many systems are closed loop systems. Some...
Pulsation Damper 1
The rapid opening and closing of the fuel injectors cause pressure fluctuations in the fuel rail. The result is that the amount of injected fuel will be more or less than the desired amount. Mounted on the fuel rail, the pulsation damper reduces these pressure fluctuations. When pressure suddenly begins to increase the spring loaded diaphragm retracts slightly increasing fuel rail volume. This will momentarily prevent fuel pressure from becoming too high. When pressure suddenly begins to drop,...
Electronic Spark Advance Overview
In the Electronic Spark Advance ESA system, the engine is provided with nearly ideal ignition timing characteristics. The ECM determines ignition timing based sensor inputs and on its internal memory, which contains the optimal ignition timing data for each engine running condition. After determining the ignition timing, the ECM sends the ignition Timing signal IGT to the igniter. When the IGT signal goes off, the Igniter will turn on shut off primary current flow in the ignition coil producing...
EVAP System Pressure Test Diagnosis
The Enhanced I M Evaporative Pressure Test is performed by filling the EVAP vapor line and fuel tank with nitrogen to a pressure of 14 inches of water approximately 0.5 psi . If the system maintains at least 8 inches of water pressure after 2 minutes, it passes the test. Because of difficulty regulating compressed air, and the hazardous nature of introducing oxygen to stored fuel vapors, never attempt to pressurize the EVAP system using shop air If the EVAP system fails the pressure test, a...
ECM Controlled EVAP System Operation
Introduced on the'95 Avalon for CA, this system is similar to the Non-ECM controlled systems, except that an ECM controlled Vacuum Switching Valve VSV is used in place of the Thermo Vacuum Valve TVV . The VSV is normally closed and duty cycle controlled, which means the ECM rapidly opens and closes the VSV passage to provide precise, variable control of purge flow volume and inhibit operation. Because this system uses a manifold vacuum purge port, it may provide slight purge flow during idle if...
Mass Air Flow Sensor Hot Wire Type
The primary components of the MAF sensor are a thermistor, a platinum hot wire, and an electronic control circuit. The thermistor measures the temperature of the incoming air. The hot wire is maintained at a constant temperature in relation to the thermistor by the electronic control circuit. An increase in air flow will cause the hot wire to lose heat faster and the electronic control circuitry will compensate by sending more current through the wire. The electronic control circuit...
Procedures to Retrieve Trouble Codes
There are several different types and locations of diagnostic connectors which are used to trigger and, in some cases, read diagnostic code output from Toyota EFI engines. All late model TCCS applications, from 1988, use a multiple terminal diagnostic check connector. Earlier models use this same multiple terminal or a two-terminal check connector, all located under the hood. The procedure to examine the ECU memory for diagnostic codes is typically very simple regardless of which vintage engine...
Info Vjg
The ECM is able to distinguish which coil is not operating based on when the IGF signal is received. Since the ECM knows when each cylinder needs to be ignited, it knows from which coil to expect the IGF signal. The major advantages of DIS with independent ignition are greater reliability and less chance of cylinder misfire.
Karman Vortex Air Flow Meter Ks
The Karman vortex air flow meter is currently used on the 7M-GTE Toyota engine and the 2JZ-GE and 1UZ-FE Lexus engines. It is located in the air induction system inlet pipe between the air cleaner and the throttle body. The sensor is composed of a photocoupler and mirror, a vortex generator, and an integrated circuit IC which together, measure the frequency of the vortices generated by air entering the intake system. When compared with the vane type air flow meter, the Karman vortex meter is...
Malfunction Indicator Light Illumination
Once a malfunction has been established two trip detection logic where applicable the MIL will illuminate and remain illuminated even if the condition is intermittent. The MIL will remain on after subsequent restarts even if the malfunction condition is no longer present. The OBD-II system can only extinguish the MIL if the malfunction does not reoccur during three subsequent sequential trip cycles. The OBD-II system can only erase a stored DTC if the malfunction is not detected during forty...
Stateofcharge Test
The state-of-charge test checks the battery's chemical condition. One method uses a hydrometer to measure the specific gravity of the electrolyte. Another method uses a digital voltmeter to check the battery's open circuit voltage and, for a general indication of the battery's condition, check the indicator eye if the battery has one or check the headlamp brightness during starting. Specific gravity means exact weight. The hydrometer compares the exact weight of electrolyte with that of water....
Shift Lock Override Button
In order to move the shift lever out of Park, the ignition switch must be in the Accessory or ON position and the brake pedal must be depressed. When the brake pedal is depressed, the ECU turns on the solenoid, moving the plate stopper and allowing the shift lock plate to move down with the grooved pin. If the shift lock solenoid becomes inoperative, the shift lever cannot be moved and the vehicle cannot be moved. The shift lock override button can be used to release the plate stopper from the...
Firing Order
The firing order can be found in the New Car Features book. The cylinders are identified as follows V-8 engine cylinders are numbered with odd numbered cylinders on the left bank and even numbered cylinders on the right bank. V-6 engine cylinders are numbered with even on left bank and odd numbered cylinders on the right bank. In-line 6 engines are numbered consecutively 1-6, with the number I cylinder at the front. Four cylinder engines are numbered consecutively from front to back. Many...
StepMotor IAC System
This system uses a step-motor type IACV to control bypass airflow. The IACV consists of a stepmotor with four coils, magnetic rotor, valve and seat, and can vary bypass airflow by positioning it's valve into one of 125 possible steps. Basically, the higher the IACV step number, the larger the airflow opening and the greater the volume of air bypassed around the closed throttle. The ECM controls IACV positioning by sequentially energizing its four motor coils. For each coil that is pulsed, the...
OnOff Control Vacuum Switching Valve VISC System
The simple On-Off Vacuum Switching Valve VSV ISC system is controlled by signals from the ECU or directly by tail lamp and rear window defogger circuits. The Vacuum Switching Valve VSV is typically located on the engine often under the intake manifold or in the engine compartment, controlling a fixed air bleed into the intake manifold. The valve is a normally closed N Q design which is opened when current is passed through the solenoid windings. Unlike most ECU controlled circuits which are...
A Small Test Light Will Not Find Some ShorttoGrounds
All the ground paths in this circuit will cause the light to be bright with or without the short-to-ground present. A larger load such as a headlight requires more current flow will work better. 15A ' 15A ' , 20A 7.5A 7.5A 15A J5Aj JOA JOA J5A ' 30A ' 40 A STARTER HEAD RH USA HEAD LH USA 2 gt i O . lt S lt vi Some technicians use a short finder or circuit breaker in place of the fuse. A short finder kit consists of a circuit breaker and a low-quality inductive type ammeter or compass. While the...
Barometric Pressure Sensor
The Barometric Pressure Sensor, sometimes called a High Altitude Compensator HAC , measures the atmospheric pressure. Atmospheric pressure varies with weather and altitude. At higher elevations the air is less dense, therefore, it has less pressure. In addition, weather changes air pressure. This sensor operates the same as the MAP sensor except that it measures atmospheric pressure. It is located inside the ECM. If it is defective, the entire ECM must be replaced.
Causes of Excessive Hydrocarbons
As mentioned, high hydrocarbons is most commonly caused by engine misfires. The following list of problems could cause high HC levels on fuel injected vehicles. As with any quick reference, there are other less likely causes that may not be included in the list. Here are some of the more common causes -faulty ignition secondary component -faulty individual primary circuit on distributorless ignition system -weak coil output due to coil or primary circuit problem Excessively lean air fuel...
MAP Sensor Diagnosis
The MAP sensor can cause a variety of driveability problems since it is an important sensor for fuel injection and ignition timing. Visually check the sensor, connections, and vacuum hose. The vacuum hose should be free of kinks, leaks, obstructions and connected to the proper port. The VC VCQ wire needs to supply approximately 5 volts to the MAP sensor. The E2 ground wire should not have any resistance. Sensor calibration and performance is checked by applying different pressures and comparing...
Throttle Position Sensor 1
The TPS is mounted on the throttle body and converts the throttle valve angle into an electrical signal. As the throttle opens, the signal voltage increases. The ECM uses throttle valve position information to know engine mode idle, part throttle, wide open throttle. switch off AC and emission controls at Wide Open Throttle WOT . The basic TPS requires three wires. Five volts are supplied to the TPS from the VC terminal of the ECM. The TPS voltage signal is supplied to the VTA terminal. A...
Carbon Dioxide CO
Carbon dioxide, or CO2, is a desirable byproduct that is produced when the carbon from the fuel is fully oxidized during the combustion process. As a general rule, the higher the carbon dioxide reading, the more efficient the engine is operating. Therefore, air fuel imbalances, misfires, or engine mechanical problems will cause CO2 to decrease. Remember, ideal combustion produces large amounts Of CO2 and H2O water vapor .
Causes of Excessive Exhaust Emissions
As a general rule, excessive HC, CO, and NOx levels are most often caused by the following conditions Excessive HC results from ignition misfire or misfire due to excessively lean or rich air fuel mixtures Excessive CO results from rich air fuel mixtures Excessive NOx results from excessive combustion temperatures There are lesser known causes to each of these emissions that will be discussed later. When troubleshooting these types of emissions failures, you will be focusing on identifying the...
Assignmentname Emh
1. Describe the basic construction of a lead-acid battery. 2. Explain what materials are used to make up the positive plate, negative plate, and electrolyte. 3. Describe the basic chemical operation of a single cell that makes a battery. 4. List the voltage output of both a single battery cell and a six cell automotive battery. Be exact. 5. Explain the four basic battery capacity ratings systems. 6. List the gases that are produced during the charging process from both the positive and the...
Oxides of Nitrogen NOx Emission
High cylinder temperature and pressure which occur during the combustion process can cause nitrogen to react with oxygen to form Oxides of Nitrogen NOx . Although there are various forms of nitrogen-based emissions that comprise Oxides of Nitrogen NOx , nitric oxide NO makes up the majority, about 98 of all NOx emissions produced by the engine. Generally speaking, the largest amount of NOx is produced during moderate to heavy load conditions when combustion pressures and temperatures are their...
Variable Resistors
Three types of variable resistors are used rheostats, potentiometers, and thermistors. RHEOSTAT - Toyota uses a rheostat on the headlamp switch to dim or brighten dash panel lighting. Rheostats have two connections one to the fixed end of a resistor, one to a sliding contact on the resistor. Turning the control moves the sliding contact away from or toward the fixed end, increasing or decreasing the resistance. POTENTIOMETER - Toyota uses a potentiometer in the EFI airflow meter. Potentiometers...
ECT Analyzer
The ECT Analyzer is designed to determine if a transmission malfunction is ECU electrical circuit related or in the transmission. The analyzer is connected at the solenoid electrical connector using appropriate adapter harnesses. The vehicle is driven using the analyzer to shift the transmission. If the transmission operates properly with the ECT Analyzer, the fault lies between the solenoid connectors up to and including the ECU. On the other hand, if the transmission does not operate properly...
Air Conditioning Idleup
The air conditioning idle-up system is used to increase engine idle rpm any time the air conditioning compressor is in operation. The system shown is used on D type EFI applications where the ECU controlled Idle Speed Control Valve ISCV does not have an A C idle-up feature. This system maintains engine idle stability during periods of A C compressor operation. Additionally, it keeps compressor speed sufficiently high to ensure adequate cooling capacity at idle speed. The A C idle-up system...
Mass Air Flow MAF Sensors
The Mass Air Flow Sensors converts the amount of air drawn into the engine into a voltage signal. The ECM needs to know intake air volume to calculate engine load. This is necessary to determine how much fuel to inject, when to ignite the cylinder, and when to shift the transmission. The air flow sensor is located directly in the intake air stream, between the air cleaner and throttle body where it can measure incoming air. There are different types of Mass Air Flow sensors. The vane air flow...
Engine Detonation Knock Signal KNK Knock Sensor
The knock sensor is a piezoelectric device mounted to the cylinder block which generates a voltage whenever it is exposed to vibration. When engine detonation occurs, vibration of the cylinder block causes the sensor to generate a voltage signal. The sensor signal varies in amplitude depending on the intensity of knock. Typically, detonation vibration occurs in the 7KHz range 7 thousand cycles per second . Knock sensor and ECU designs take advantage of this fact. There are two different types...
NE Signal and G Signal 1
Though there are different types of ignition systems, the use of the NE and G signals is consistent. The NE signal indicates crankshaft position and engine RPM. The G signal also called VVT signal provides cylinder identification. By comparing the G signal to the NE signal, the ECM is able to identify the cylinder on compression. This is necessary to calculate crankshaft angle initial ignition timing angle , identify which coil to trigger on Direct Ignition System independent ignition , and...
IGT Signal
The primary coil current flow is controlled by the ECM through the Ignition Timing IGT signal. The IGT signal is a voltage signal that turns on off the main transistor in the igniter. When IGT signal voltage drops to 0 volts, the transistor in the igniter turns off. When the current in the primary coil is turned off, the rapidly collapsing magnetic field induces a high voltage in the secondary coil. If the voltage is high enough to overcome the resistance in the secondary circuit, there will be...
How to Determine Fuel System Loop Status
Long FT and LVF only learns during closed loop operation. Therefore, the engine must be operating in closed loop when performing tests involving fuel trim data. To confirm closed loop operation, refer to the following chart Accessed at VF1 terminal of check connector, TE1 on, IDL CTP off Varying between 0 and 5 volts indicates closed loop Fixed voltage indicates open loop operation An alternate method of determining closed loop operation on all vehicles with DLC 1 Check Connector is to use your...
IGF Signal Detection using CEMF
There are two basic methods of detecting IGF. Early systems used the Counter Electromotive Force CEMF created in the primary coil and circuit for generating the IGF signal. The collapsing magnetic field produces a CEMF in the primary coil. When CEMF is detected by the igniter, the igniter sends a signal to the ECM. This method is no longer used. IGF Detection through Primary Current lA Maximum current level for successful spark generation lB Minimum current level for successful spark generation...
Distributorless Direct Ignition Systems Overview
Essentially, a Distributorless Ignition System is an ignition system without a distributor. Eliminating the distributor improved reliability by reducing the number of mechanical Greater control over ignition spark generation - There is more time for the coil to build a sufficient magnetic field necessary to produce a spark that will ignite the air fuel mixture. This reduces the number of cylinder misfires. Electrical interference from the distributor is eliminated - Ignition coils can be placed...