Vehicle Sensors & Throttle Position Sensor (TPS)

Sensors in Vehicles

• Sensors are electrical devices that monitor a vehicle's operating conditions.
• They transmit information to the control units to ensure proper functioning.
• They detect malfunctions and alert the control units.

TPS Sensor (Throttle Position Sensor)

• The TPS sensor monitors the position of the throttle valve.
• It sends signals to the Electronic Control Module (ESM).
• The ESM regulates fuel injection into the combustion chamber.
• The TPS indicates how far the driver is pressing the accelerator pedal.
• The sensor functions as a potentiometer, with a variable linear resistance.
• It is supplied with 5V, which is a common voltage for most car brands.
• The resistance varies in proportion to the signal, sending a return signal to the ESM for calculating engine acceleration.

TPS Wiring

• The circuit consists of three wires: ground, 5V power, and a signal line to the ESM.
• The end wires correspond to the voltage of the power supply and ground wires.
• The middle wire is the signal wire.
• The data translates the angle of the throttle into an electrical signal.
• The signal informs the ESM about the driver's desired acceleration or deceleration.
• It determines the amount of fuel the engine requires.

Symptoms of TPS Sensor Failure

• Unstable minimum or idle speed.
• Check engine light turns on.
• Jerking and reduced power occur.

MAF Sensor (Mass Air Flow Sensor)

• The MAF sensor measures the amount of air entering the engine.
• This is essential for calculating the air-fuel mixture.
• It detects the mass of air flowing into the engine.
• It measures air density rather than volume.
• The MAF sensor is typically located in the intake duct.
• It's positioned after the air filter and before the intake manifold.

Types of MAF Sensors

• Hot wire sensors
• Sensors of hot wire cooled by thin film
• Air flow sensors of hot vortex
• Each type has its own operating principle and measurement technology.
• The MAF sensor is essential for calculating the amount of fuel to be injected.
• Inaccurate information leads to an inadequate air-fuel mixture.
• This affects efficiency, performance, and emissions.

Problems and Efficiency

• Problems can cause loss of power, unstable idling, starting difficulties, and increased fuel consumption.
• Crucial for fuel efficiency, the MAF sensor allows the engine management system to adjust fuel injection based on demand.
• The MAF prevents excessive fuel use and reduces emissions.

MAP Sensor (Manifold Absolute Pressure Sensor)

• The MAP sensor measures the absolute pressure of the intake manifold.
• It provides information about the engine load.
• The sensor measures pressure in the intake manifold and is used to calculate the amount of fuel to inject and adjust ignition timing.
• Located in the intake manifold, the sensor converts absolute pressure into an electrical signal.
• The pressure in the intake manifold changes with the engine load.
• The information impacts the engine's efficiency, performance, and emissions.

MAP Symptoms and Turbocharged Motors

• Problems can cause loss of power, unstable idling, starting difficulties, and increased fuel consumption.
• Turbocharged engines use the MAP sensor to measure boost pressure.
• The MAP sensor allows the engine to adjust fuel and air to increase power safely.

CKP Sensor (Crankshaft Position Sensor)

• The CKP sensor monitors the position and speed of the crankshaft.
• This allows the engine management system to time fuel injection and spark.
• The sensor detects the position and speed of the engine's crankshaft.
• This information is critical for fuel injection and ignition timing.
• The CKP sensor is typically located near the flywheel or the crankshaft's front.

Types of CKP Sensors

• Magnetic reluctance sensors
• Hall effect sensors
• Optical sensors
• Essential for synchronization of fuel injection and spark, contributing to overall engine efficiency.

Symptoms of CKP Sensor Issues

• The car will not start.
• The check engine light will turn on.
• There can be a sudden power loss.

IAT Sensor (intake Air Temperature Sensor)

• The IAT sensor monitors the temperature of the air entering the engine.
• The ECU adjusts fuel and ignition based on air temperature.
• Typically located in the air intake system, near the air filter.
• The IAT sensor has a thermistor that changes electrical resistance.
• The ECU measures this resistance to determine air temperature.

IAT Sensor Issues

• Increased carbon monoxide emissions
• Exaggerated fuel consumption
• Difficulties in cold starting
• Higher acceleration
• Over-fueled motors
• The computer cannot adequately control the ignition timing.
• For supercharged engines, the sensor adjusts boost pressure to enhance power and performance.

ECT Sensor (Engine Coolant Temperature Sensor)

• The ECT sensor measures the temperature of the engine coolant.
• It provides this information to the ECU.
• Essential for calculating fuel injected and adjusting ignition timing.
• The ECT sensor is typically located on or near the engine, near the thermostat or engine block.
• The ECT sensor uses a thermistor to measure coolant temperature.
• The sensor contributes to fuel efficiency.
• Essential for allowing the ECU to adjust the air-fuel mixture based on engine temperature.

CMP Sensor (Camshaft Position Sensor)

• The CMP sensor monitors the position and speed of the camshaft.
• This enables the ECU provides this information to adjust engine functions.
• The location varies based on engine design (either intake or exhaust camshaft).
• Utilizes Hall effect, magnetic reluctance, or inductive sensors.
• The sensor detects slots on the camshaft during rotation.
• It generates electrical signals based on the camshaft's position.

Symptoms of CMP Sensor Failure

• The car will not start.
• The check engine light will turn on.
• Sudden power loss occurs.
• Plays a key role in engine performance, adjusting camshaft timing for optimal power and efficiency.

Oxygen Sensors

• Oxygen sensors (lambda probes) monitor the oxygen level in the exhaust gases.
• This provides the unit control critical information to the engine.
• They help the ECU determine if the air-fuel mixture is rich (more fuel) or lean (less fuel).

Types of Oxygen Sensors

• Wideband sensors
• Narrow band sensors
• Wideband sensors (provide more accurate readings)
• Narrow band sensors
• Vehicles have at least two oxygen sensors.
• One sensor in the exhaust manifold before the catalytic converter.
• One sensor after the catalytic converter.

Oxygen Issues, Role, and Emission

• Problems can cause increased fuel consumption.
• The engine warning light may turn on.
• Unstable idling or power loss can occur.
• The sensors are important in emission control.
• It helps the catalytic converter reduce emissions of polluting gases.

Knock Sensor (Detonation Sensor)

• The knock sensor detects uncontrolled engine detonations.
• The sensor monitors vibrations and sounds of uncontrolled engine detonation.
• This information allows the unit control to prevent engine damage.
• The detonation sensor is usually mounted on the engine block or cylinder head.
• It's placed near areas where detonations are generated.
• It uses a piezoelectric crystal that converts vibrations into electrical signals.
• The signals are processed by the ECU to identify detonation.
• The sensor is critical in high-performance engines to prevent damage from high loads and temperatures.

VSS (Vehicle Speed Sensor)

• The VSS measures the speed at which the vehicle is moving.
• It provides speed data to the engine and transmission control units.
• Located near the transmission, gearbox, or rear differential, depending on the vehicle.
• It uses magnetic or electronic technology to measure the speed of the vehicle's wheels.
• This information allows the engine and transmission to adjust operations.
• Converted into an electrical signal and transmitted to the ECU.

Symptoms of VSS Sensor Failure

• Cruise control does not function.
• There are abrupt or inappropriate gear changes.
• The engine warning light is on.

Actuators

• Automotive actuators convert electrical, hydraulic, pneumatic, or mechanical signals into physical actions.
• Actuators are essential for operations within a vehicle.
• They play a role in a car's functioning.

Types of Actuators

• Electromagnetic:
• Heating
• Electromotor
• LCD

Electromagnetic Actuators

• Any physical device able to create a uniform magnetic field zone can function thanks to magnetism.
• Electromagnets have relays, injectors, and starter motor solenoids.
• Relays help to control high-voltage currents with a small control current.
• It has two circuits, one for power from the battery and one control circuit.
• Fuel injectors have a valve body, coil, and injector needle.
• The starter motor solenoid connects the electric motor pinion to the flywheel ring gear.
• It works under the same principle.

Heating Actuators

• Heating actuators generate heat based on the Joule effect.
• This effect relates the current passing through a resistance and the energy released as heat.
• They use heating resistors made of metal alloys or semiconductor compounds.
• Glow plugs in diesel engines facilitate cold starts.
• Self-regulating as quick heating with PTC resistance.
• Other applications include electric radiators for vehicle heating systems.
• Furthermore, intake manifold heating resistors, thermal windows, and rearview mirrors.

Electromotor Actuators

• Electromotor actuators convert electrical energy into mechanical energy.
• This is seen in fuel pumps, window lifters, and windshield wiper motors.
• Fuel pumps have an armature that receives current and rotates the rotor with rollers.
• The rotor creates a centrifugal force to move the rollers outward.
• The rollers act as a rotary joint.

Stepper motors

• Has permanent magnet rotors and stator coils.
• Other motors include electric power steering systems and automatic ventilation duct regulation.