The modern injection engine is controlled by a variety of sensors. But the electronic control system of the motor may not always be the cause of its breakdown. Therefore, before checking the serviceability of the sensors, make sure that the remaining parts and parts of the power unit are working properly. The only fact that directly indicates a malfunction of any sensor is the Check Engine lamp on the instrument panel.
It is necessary
a tool for dismantling interfering parts; - ohmmeter (multimeter)
Instructions
Step 1
The throttle position sensor (TPS) is a variable resistor. To test it, measure the resistance between its terminals. Compare the readings with the factory values indicated in the operating instructions (different machines have different sensors). A discrepancy of 20% is considered normal. Also, a malfunction of the TPS may be indicated by the instability of the idle speed, jumps during the increase in speed.
Step 2
The knock sensor cannot be tested without specialized equipment. An indirect sign of its breakdown is increased detonation when the engine is running. For diagnostics and replacement of the sensor, contact a specialist. The same applies to the timing sensor. It is only installed on engines with four valves per cylinder. Its check is carried out using special diagnostic devices.
Step 3
If the engine refuses to start, this is a symptom of a malfunctioning crankshaft position sensor. This sensor is the only one, in the event of a breakdown of which the motor refuses to start. To carry out an additional check, measure the resistance between the terminals, having disconnected the connector in advance. Normally, this figure should be equal to 550-750 ohms.
Step 4
Also, the cause of a malfunction of the crankshaft position sensor can be a controller installed on the master disk of the crankshaft pulley. The rubber damper mounted on the controller gear wheel can rotate against the pulley. To check this, look for the marks on the camshaft and flywheel. By the way, the mark on the flywheel duplicates the mark on the crankshaft. If the roller is positioned correctly, the indicated marks coincide, and between the two missing teeth between the master disk and the axis of the crankshaft sensor, 19-20 teeth of the master disk fit.
Step 5
To check the mass air flow sensor, disconnect the wiring block suitable for it. Then measure the resistance between the terminal indicated in the electronic engine control circuit diagram and ground. As a rule, it should be equal to 4-6 kOhm. Or remove the sensor from the running engine. At the same time, the engine will not lower the rpm below 1500. Also, a sign of a malfunction of the air flow sensor is the unstable operation of the power unit, its difficult start, delays, jumps, dips while driving, insufficient power and traction of the car.
Step 6
To check if the speed sensor is working, shift into neutral while the vehicle is idling. With a working sensor, the revolutions will increase slightly. On VAZ-2110/2111/2112 cars, with a faulty speed sensor, the speedometer stops working.
Step 7
To check the coolant temperature sensor, find a special table in the repair documentation. A change in temperature in the cooling system must be accompanied by a change in the resistance of this sensor according to the data in the table.
Step 8
Check the oxygen sensor by measuring the resistance of the heater, having previously disconnected the connector from it. The result should be between 0.5 and 10 ohms, depending on the sensor model. Please refer to the repair instructions for exact details. Also, to check it, remove the connector from the sensor, turn on the ignition and measure the reference voltage of the crankshaft position sensor controller, which should be 0.45 V.
