Pic. 2.367. Location of system components: 1 - coolant temperature sensor (ECT); 2 - air flow sensor and air temperature sensor in the intake manifold for a model with a 2.4 I4 engine; 3 - air flow sensor for a model with a 2.7 V6 engine; 4 - air temperature sensor in the intake manifold (IAT) for model with 2.7 V6 engine; 5 - throttle position sensor (TPS); 6 - idle speed control servo drive (ISA); 7 - oxygen sensor with heater (HO2S); 8 - camshaft position sensor (SMR); 9 - crankshaft position sensor (TFR); 10 - nozzle; 11 - solenoid valve purge adsorber (PCSV); 12 - knock sensor (KS); 13 - sensor-switch of fluid pressure in the hydraulic system of the power steering.
Coolant temperature sensor (ECT SENSOR)
Pic. 2.368. coolant temperature sensor
The coolant temperature sensor is installed in the channel of the cylinder head cooling jacket. It detects the temperature of the engine coolant and transmits a signal to the electronic engine control unit. The sensor is a thermistor sensitive to temperature changes. The resistance of the sensor decreases as the temperature of the engine coolant increases. Based on the voltage of the sensor signal, the electronic engine control unit estimates the temperature of the coolant and provides an enrichment of the air-fuel mixture when the engine warms up.
Checking with the HI-SCAN tester (PRO)
Data to check with the HI-SCAN tester (PRO) presented in table 2.32.
Checking with a multitester
Remove the coolant temperature sensor from the engine intake manifold.
Pic. 2.369. Measuring resistance between sensor leads
Immerse the measuring part of the sensor in water with a known temperature and measure the resistance between the sensor leads (pic. 2.369).
Pic. 2.370. Valid Value Chart
If the measured resistance differs from the nominal values, then replace the coolant temperature sensor (pic. 2.370).
Troubleshooting Guide
If the idle speed when warming up a cold engine is not correct, or warming up the engine is accompanied by black smoke from the exhaust pipe, then the coolant temperature sensor may be the cause.
Sensor installation
Apply the specified sealant to the sensor threads.
Recommended sealant: LOCTITE 962T or equivalent.
Install the sensor in place and tighten it to the rated torque.
The moment of an inhaling of the gauge of temperature of a cooling liquid: 15–20 Н·м.
Connect the sensor connector securely.
Air flow sensor (MAF) and intake manifold air temperature sensor (IAT)
The film-type sensor consists of a temperature-sensitive film, a housing and a measurement zone (hybrid type). The principle of air flow measurement with this type of sensor is based on the change in heat transfer from the film surface to the flow of air flowing through the sensor.
The air flow sensor generates oscillatory pulses (gap-short) in the range of 5 V, which are supplied from the electronic engine control unit.
Intake manifold air temperature sensor (IAT), located in the inlet pipe, resistor type; it measures the temperature of the air. Information about the temperature state of the air in the intake manifold allows the electronic engine control unit to measure the optimal amount of fuel injected through the nozzles into the engine with greater accuracy.
Troubleshooting Tips
If the engine suddenly stalls, restart it and then move the MAF sensor harness. If the engine stalls in this case, check for a loose connection at the MAF sensor connector.
If the output voltage at the MAF sensor is different from «0» with the ignition on (the engine is not running), check the condition of the MAF sensor itself or the electronic engine control unit (RSM).
If the engine is idling despite the sensor output voltage being abnormal, check the following:
- The possibility of changing the direction of air flow in the intake manifold, detaching the air pipe, clogged air filter. Incomplete combustion of fuel in the combustion chamber, malfunction of spark plugs, ignition coils, injectors or their incorrect interaction.
- If there are no signs of a malfunction of the MAF sensor, check the correct installation.
Note. If the car is new (its mileage is no more than 500 km), the mass air flow sensor reading is 10% higher than the actual air flow.
Note. The use of a digital voltmeter is recommended for testing.
Note. Before starting the test, it is necessary to warm up the engine to a coolant temperature of 80–90°C.
Air flow sensor (MAF 2.7 V6)
Pic. 2.371. Air flow sensor
The film-type sensor consists of a temperature-sensitive film, a housing and a measurement zone (hybrid type). The principle of air flow measurement with this type of sensor is based on the change in heat transfer from the film surface to the flow of air flowing through the sensor. The air flow sensor generates oscillatory pulses (gap-short) in the 5 V range (see table. 2.35), which are supplied from the electronic engine control unit.
Troubleshooting Guide
If the engine suddenly stalls, restart it and then move the MAF sensor harness. If the engine stalls in this case, check for a loose connection at the MAF sensor connector.
If the output voltage at the MAF sensor is different from «0» with the ignition on (the engine is not running), check the condition of the MAF sensor itself or the electronic engine control unit (RSM).
If the engine is idling despite the sensor output voltage being abnormal, check the following:
- The possibility of changing the direction of air flow in the intake manifold, detaching the air pipe, clogged air filter.
- Incomplete combustion of fuel in the combustion chamber, malfunction of spark plugs, ignition coils, injectors or their incorrect interaction.
- If there are no signs of a malfunction of the MAF sensor, check the correct installation.
Note. If the car is new (its mileage is no more than 500 km), the mass air flow sensor reading is 10% higher than the actual air flow.
Note. The use of a digital voltmeter is recommended for testing.
Note. Before starting the test, it is necessary to warm up the engine to a coolant temperature of 80–90°C.
Intake manifold air temperature sensor (IAT SENSOR)
The intake manifold air temperature sensor is integrated into the intake manifold absolute pressure sensor (MAP). The sensor is a resistor that changes the signal voltage depending on the temperature of the air entering the intake manifold.
In accordance with the signal from the air temperature sensor in the intake manifold, the electronic engine control unit will adjust the required fuel supply (basic fuel injector open time).
Troubleshooting Guide
Under the following conditions, the engine malfunction indicator lamp lights up and on the HI-SCAN tester (PRO) the corresponding fault code is displayed.
When the intake manifold air temperature detected by the sensor is below -40°C or above 120°C.
When the input signal from the intake manifold air temperature sensor is below 0.1V or above 4.8V when the engine is warm.
Sensor test
Using a multimeter, measure the output voltage of the sensor
Measure the voltage between terminals 1 and 2 of the intake manifold air temperature sensor (IAT)
If the voltage is significantly different from the nominal value, then replace the air temperature sensor in the intake manifold (IAT) assembled.
Throttle position sensor (TPS)
Pic. 2.372. Throttle position sensor
The throttle position sensor is a sliding contact potentiometer that moves according to the rotation of the throttle shaft, indicating the opening angle of the throttle. When the throttle axis is rotated, the voltage of the throttle position sensor signal changes and, based on the change in the value of the sensor signal voltage and the rate of its change, the electronic engine control unit determines the degree and speed of opening the throttle.
Sensor test
Data to check with the HI-SCAN tester (PRO) presented in table 2.38.
Checking with a voltmeter
Disconnect the throttle position sensor connector.
For model with 2.4 I4 engine, measure the resistance between terminal 1 («weight» sensor) and output 2 (sensor power supply), and for a model with a 2.7 V6 engine between terminal 2 («weight» sensor) and output 1 (sensor power supply).
Rated value: 3.5-6.5 kΩ.
Pic. 2.373. Ohmmeter connection
Connect an analog type ohmmeter to pin 1 («weight» sensor) and conclusion 3 (sensor signal) throttle position sensor for model with 2.4 I4 engine and to pin 2 («weight» sensor) and conclusion 3 (sensor signal) for model with 2.7 V6 engine (pic. 2.373).
Slowly opening the throttle from a fully closed (idling) in the fully open position, check that the resistance changes smoothly in proportion to the throttle opening angle.
Pic. 2.374. Output voltage diagram
If the resistance is either different from the nominal value or does not change smoothly, then replace the throttle position sensor.
Throttle position sensor tightening torque: 1.5–2.5 Nm.
Troubleshooting Guide
The throttle position sensor signal is more important to the automatic transmission control system than to the engine management system. If the throttle position sensor is faulty, then «percussion» (jerk) gear shifting and other malfunctions may occur.
Idle speed control servo (ISA)
The idle speed control servo is an electric motor with two windings, which are switched on by separate control circuits of the electronic engine control unit.
Depending on the duty cycle of the pulse period («pulse duty factor») the difference in the magnetic forces of the two windings will rotate the motor shaft at a certain angle, thus changing the flow area of the bypass channel. The bypass port is located in the throttle body parallel to the throttle port at the location where the idle speed control servo is installed.
Troubleshooting Guide
The engine malfunction indicator lamp is on or on the HI-SCAN tester (Pro) the corresponding fault code is issued under the following condition (see table 2.39).
When the primary voltage circuit in the PCM is either open or in a short circuit condition.
When the PCM control of the ignition system is broken.
An open or short circuit in the idle speed control servo circuit can be detected immediately after the ignition is turned on.
Oxygen sensor with heater (HO2S 2.4L)
The oxygen sensor determines the concentration of oxygen in the exhaust gases and accordingly changes the voltage of the signal that enters the electronic engine control unit.
If the composition of the air-fuel mixture is richer than the stoichiometric ratio (those. if the oxygen concentration in the exhaust gases is low), then the sensor signal voltage is approximately 1 V. If the air-fuel mixture is leaner than the stoichiometric ratio (those. if the concentration of oxygen in the exhaust gases is high), then the voltage of the sensor signal is approximately 0 V. Based on this signal, the electronic engine control unit regulates the fuel supply so that the composition of the air-fuel mixture is as close to the stoichiometric ratio as possible. Oxygen sensor (zirconium) equipped with a heater, which ensures stable operation of the sensor in all modes.
Troubleshooting Guide
If the oxygen sensor is defective, then the exhaust gases will contain an increased content of toxic substances.
If the oxygen sensor signal (output voltage) differs from the nominal value, after the test showed that the sensor is working, then the cause of the malfunction in the components of the air-fuel mixture control system:
- injector malfunction;
- air enters the intake manifold through a damaged gasket;
- intake manifold absolute pressure sensor malfunction (MAP), air flow sensor, intake manifold air temperature sensor and coolant temperature sensor.
Sensor test
Replace the oxygen sensor if it is defective.
Apply battery voltage to terminals 3 and 4.
Note. Before checking, warm up the engine so that the coolant temperature reaches 80-95°C.
Note. When taking measurements, use an ultra-precise digital voltmeter.
Note. Disconnect the oxygen sensor connector and measure the resistance between pin 3 and pin 4.
Rated value
Note. Be careful when performing this operation. Accidental voltage supply to terminals 1 and 2 will damage the oxygen sensor.
Pic. 2.375. Scheme of connecting the sensor connector to the voltmeter
Connect a high internal resistance digital voltmeter between pins 1 and 2 (pic. 2.375).
Sequentially accelerating the engine, measure the output voltage of the oxygen sensor.
If there are deviations, a malfunction of the oxygen sensor is possible.
Oxygen sensor tightening torque: 50–60 Nm.
Oxygen sensor with heater (HO2S 2.7L)
Pic. 2.376. Oxygen Sensor Connector, Wiring Harness Side
The oxygen sensor determines the concentration of oxygen in the exhaust gases and accordingly changes the voltage of the signal that enters the electronic engine control unit. If the composition of the air-fuel mixture is richer than the stoichiometric ratio (those. if the oxygen concentration in the exhaust gases is low), then the sensor signal voltage is approximately 0 V.
If the air-fuel mixture is leaner than the stoichiometric ratio (those. if the concentration of oxygen in the exhaust gases is high), then the voltage of the sensor signal is approximately 5 V. Based on this signal, the electronic engine control unit regulates the fuel supply so that the composition of the air-fuel mixture is as close to the stoichiometric ratio as possible. The oxygen sensor is equipped with a heater, which ensures stable operation of the sensor in all modes.
Troubleshooting Guide
If the oxygen sensor is defective, then the exhaust gases will contain an increased content of toxic substances.
If the oxygen sensor signal (output voltage) differs from the nominal value, after the test showed that the sensor is working, then the cause of the malfunction in the components of the air-fuel mixture control system:
- injector malfunction;
- air enters the intake manifold through a damaged gasket;
- malfunction of the air flow sensor, intake manifold air temperature sensor and coolant temperature sensor.
Checking with a voltmeter
Disconnect the oxygen sensor connector and measure the resistance between terminals 3 and 4.
Note. Before checking, warm up the engine so that the coolant temperature reaches 80-95°C.
Note. Be especially careful when performing this check. If connected incorrectly or if the terminals are shorted to each other, it leads to failure of the oxygen sensor.
Connect a high internal resistance digital voltmeter between pins 1 and 2.
After accelerating the engine several times, measure the output voltage of the oxygen sensor.
The presence of deviations in the readings may indicate a malfunction of the oxygen sensor.
Oxygen sensor tightening torque: 40–50 Nm.
Camshaft position sensor
The principle of operation of the camshaft position sensor is based on the Hall effect. The sensor determines the moment when the pistons of cylinders No. 1 and No. 4 arrive at top dead center on the compression stroke.
Based on the signal from the sensor, the electronic engine control unit determines the sequence of fuel injection for individual cylinders.
Troubleshooting Guide
If the camshaft position sensor is unstable, then the consequence of this may be a violation of the fuel injection sequence for the cylinders, and this, in turn, leads either to the fact that the engine stalls, or to its unstable idling, or to the impossibility of its normal overclocking.
Crankshaft position sensor
crankshaft position sensor (TFR) uses the Hall effect, which allows you to determine the position of the crankshaft (piston position), then convert this into a signal and apply this signal to the electronic engine control unit (RSM). Based on this input signal, the PCM controls the timing of fuel injection into the cylinders and the ignition timing.
Troubleshooting Guide
When unexpected shocks occur during movement (knocks) or suddenly the engine suddenly stalls, try moving the crankshaft position sensor wiring harness. If this causes the engine to stall, check for poor contact at the connector.
If cranking the engine with the starter, the tachometer shows 0 min-1, check the engine crankshaft position sensor, timing belt or ignition system.
If the engine is idling but the crankshaft position sensor reading is abnormal, check the following:
- Faulty coolant temperature sensor;
- defective idle speed control servo;
- incorrect adjustment of the engine idle speed.
The engine can run without a signal from the crankshaft position sensor, but the engine cannot be restarted. As soon as the sensor determines the TDC position, this data is stored until the next engine start.
Nozzles
The injectors inject fuel into the engine cylinders according to a signal from the electronic engine control unit. The amount of fuel supplied by the injector is determined by the time during which the control pulse is applied to the injector winding (injector needle valve open time). The duration of the solenoid valve, in turn, is determined by the duration of the signal pulse coming from the electronic engine control unit.
Checking the injectors
Data to check with the HI-SCAN tester (PRO) presented in table 2.45.
Note. The presence of the injector control pulse is determined by the charge of the battery (not lower than 11 V) at starting engine speed not higher than 250 min-1.
If the coolant temperature is below 0°C, the ECM (RSM) provides simultaneous injection of fuel into all cylinders.
If the car is new (its mileage is no more than 500 km), the duration of the injector control pulse is approximately 10% longer than the nominal value.
Troubleshooting Guide
If there are difficulties when starting a warm engine, then check the absence of reduced pressure in the fuel lines and the tightness of the injectors.
If, when cranking the crankshaft with a starter, the engine does not start and the nozzles do not work, then check for the following faults (not related to injectors).
Malfunction of the power supply circuit of the electronic engine control unit or the connection circuit with «weight».
Faulty engine control relay and fuel pump relay.
Malfunction of the crankshaft position sensor and camshaft position sensor.
If there is no change in engine idling after turning off the injector of one of the cylinders, perform the following checks for that cylinder.
Check the injector and its wiring harness.
Check spark plug and high voltage spark plug wire.
Check compression.
If the operating time of the injector (injector opening signal duration) deviates from the nominal value, even if the test showed the injector and its wiring harness to be in good condition, then perform the following checks.
Incomplete combustion in one of the cylinders. (Faulty spark plug, ignition coil, lack of compression, etc.)
The hermetic fit of the valve in the seat of the exhaust gas recirculation system is broken (EGR)
Nozzles (2.7 V6)
The injectors inject fuel into the engine cylinders according to a signal from the electronic engine control unit. The amount of fuel supplied by the injector is determined by the time during which the control pulse is applied to the injector winding (injector needle valve open time). The duration of the solenoid valve, in turn, is determined by the duration of the signal pulse coming from the electronic engine control unit.
Checking the injectors
Data to check with the HI-SCAN tester (PRO) presented in table 2.47.
Note. The presence of the injector control pulse is determined by the charge of the battery (not lower than 11 V) at starting engine speed not higher than 250 min-1.
If the coolant temperature is below 0°C, the ECM (RSM) provides simultaneous injection of fuel into all cylinders.
If the car is new (its mileage is no more than 500 km), the duration of the injector control pulse is approximately 10% longer than the nominal value.
Checking the injector with a phonendoscope and a voltmeter. Injector Sound Check
Pic. 2.377. Checking the injector with a phonendoscope
Using a phonendoscope, check the operation of the injector (the presence of characteristic creaking sounds) when the engine is idling. Check that as the engine speed increases, the injector firing frequency also increases.
Note. Do not confuse the firing sound of the injector being tested with the firing sound of an adjacent injector transmitted through the fuel manifold, especially if the injector being tested is not working.
Pic. 2.378. Checking the injector with your finger
If a phonendoscope is not available, check the operation of the nozzle by touching it with your finger. If vibration from the injector is not felt, then check the wiring harness connector, the injector or the presence of a control pulse from the electronic engine control unit (pic. 2.378).
Checking resistance between terminals (injector solenoid coil resistance)
Disconnect the connector of the injector to be tested.
Measure the resistance between the connector pins.
Rated value: 13-16 ohms at 20°C.
Pic. 2.379. Connecting the injector connector
Connect the injector connector securely (pic. 2.379).
Canister purge solenoid valve
Pic. 2.380. Canister purge solenoid valve
The canister purge solenoid valve operates in PWM airflow control mode to purge the canister of the EVAP system.
Knock sensor
Pic. 2.381. Tetonation sensor
Knock sensor (piezoelectric) installed on the wall of the cylinder block to determine the detonation combustion of fuel in the engine cylinders. The vibration of the cylinder block caused by detonation creates pressure acting on the piezoelectric crystal in the sensor. As a result, the vibration is converted into a signal (voltage), proportional to its intensity, which is transmitted to the electronic engine control unit. If knocking occurs in the engine, the electronic engine control unit reduces the ignition timing until it disappears.
Troubleshooting Guide
The engine malfunction indicator lamp is on or on the HI-SCAN tester (Pro) the corresponding fault code is issued under the following condition.
The knock sensor signal is not detected even when the engine is overloaded.
When the knock sensor signal is below normal.
Sensor test
Disconnect the knock sensor connector.
Measure the resistance between terminals 2 and 3 of the connector.
Rated value: approx. 5 MΩ at 20°C.
If the resistance is zero, replace the knock sensor.
Knock sensor tightening torque: 16–28 Nm.
Measure the capacitance of the sensor between terminals 2 and 3 of the connector.
Rated value: 800-1600 pF.
Power steering fluid pressure switch
Pic. 2.382. Power steering fluid pressure switch
Power steering pressure switch «feels» load from the steering and transmits it in the form of an electrical signal to the electronic engine control unit (RSM). The PCM, in turn, adjusts the idle speed servo to compensate for the reduction in idle speed caused by the load on the power steering pump.
Replacing the fuel level sensor and fuel filter
Pic. 2.383. Fuel filter and sensor
Remove the filler cap from the fuel tank to relieve pressure in the fuel lines.
Jack up the vehicle, disconnect the connector from the fuel pump, then disconnect the feed and fuel return pipes from the fuel pump.
Loosen the fuel pump mounting screws and remove the fuel pump assembly from the fuel tank.
Remove the fuel level sensor and fuel filter from the fuel pump.
Check and replace if necessary.
Checking the operation of the fuel pump
Turn the ignition key to position «Off» (OFF).
Apply battery voltage to the fuel pump terminals to check that it is working.
Note. The fuel pump is located inside the fuel tank, so its performance can be determined by the characteristic sound coming from the fuel tank when the fuel pump is turned on, without removing the filler plug.
Pic. 2.384. Fuel pump check
Pinch the fuel hose with your fingers to feel the fuel pulsing when the fuel pump is running (pic. 2.384).
Checking the vacuum channel of the fuel vapor removal system
Pic. 2.385. Disconnecting the vacuum hose
Disconnect the vacuum hose from the evaporative valve on the throttle body and connect the vacuum pump (pic. 2.385).
Start the engine and check that as the engine speed increases, the vacuum constantly increases.
Note. No vacuum means the vacuum passage in the throttle body is clogged and needs to be cleaned.
Fuel pressure check
Reduce the internal pressure in the fuel system and hoses:
- Disconnect the fuel pump connector from the wiring harness side;
- start the engine and after it stalls, turn off the ignition;
- disconnect the negative terminal of the battery;
- connect the fuel pump connector from the wiring harness side.
Disconnect the fuel pipe from the fuel manifold.
Attention! Due to the presence of residual pressure in the high pressure fuel line, cover the junction of the hose with the fuel manifold with a rag to prevent fuel splashing.
Pic. 2.386. Connecting the pressure gauge to the fuel manifold
Assemble the Pressure Measurement Assembly (adapter and measuring device) and connect it to the fuel pipe and fuel manifold. Fix assembled parts with rated pressure (pic. 2.386).
Tightening torque of the pressure gauge to the fuel manifold: 25–35 Nm.
Connect the negative lead to the battery.
Apply battery voltage to the fuel pump service terminal and activate the fuel pump. As fuel pressure builds up in the system, check that there is no fuel leaking from the connections.
Start the engine and let it idle.
Pic. 2.387. Disconnecting the vacuum hose from the pressure regulator
Disconnect the vacuum hose from the pressure regulator and plug the hose with a stopper. Measure the fuel pressure in the system while the engine is idling (pic. 2.387).
Rated value: 320-340 kPa.
Measure the fuel pressure with the vacuum hose connected to the fuel pressure regulator.
Rated value: approximately 255 kPa.
If the above operations and measurements do not correspond to the nominal values, using the table below, try to determine the possible cause of the malfunction and perform the necessary remedial work.
Stop the engine and observe the pressure change in the fuel system. The pressure during the first 5 minutes should remain unchanged. If the fuel pressure drops, pay attention to the rate of pressure drop. Determine the possible problem according to the table below and correct the problem.
Reduce the fuel pressure in the system.
Disconnect the hose, remove the pressure gauge.
Attention! Due to the presence of residual pressure in the high pressure fuel line, cover the junction of the hose with the fuel manifold with a rag to prevent fuel splashing.
Replace the fuel hose end O-ring.
Connect the fuel hose to the fuel manifold and tighten to rated torque.
Make sure there is no fuel leakage.
Throttle cleaning
Pic. 2.388. Throttle assembly
Warm up the engine, then turn it off.
Note. Disconnect the intake pipe from the throttle body, check for dirt on the throttle itself. Spray solvent from an aerosol can onto the throttle body to remove debris.
Disconnect the intake manifold from the throttle body.
Plug the bypass port in the throttle body.
Note. Do not allow solvent to enter the bypass.
Spray solvent from an aerosol can onto the throttle body to remove debris. Wait about 5 minutes for the solvent to soak the dirt. Then open the throttle and wipe the soaked dirt dry with a clean rag.
Attention! When spraying solvent, keep the throttle closed to prevent solvent from entering the intake manifold.
Start the engine, accelerate it several times and let it idle for about 1 minute.
Repeat the previous two steps again.
Clear the bypass hole.
Connect the intake pipe.
Disconnect (–) battery terminal for at least 10 s.