Herve Leger 2012-vehicle engine control unit power supply relay control

control unit supply voltage

:
control unit supply voltage is an important condition of the control unit the normal
work, this data is generally marked with voltage voltage of the English abbreviation . General gasoline engines, power supply voltage of 12-14 volts. When the supply voltage below 11 volts, it could easily cause a malfunction. the
control unit supply voltage is too low, easy to cause failure:
1 Herve Leger 2012, the engine idle speed instability;
2, turn off the engine;
3, to accelerate bad;
4 engine hard initiate action.
vehicle engine control unit power supply relay control, relay control current, and so prone to failure, these vehicles, such as: red, Jetta, Santana 2000, the Audi A6 four-cylinder, the Passat .
two, the coolant temperature sensor
coolant temperature is an important correction parameters of the engine fuel injection quantity, coolant temperature display in degrees Celsius, the easier to identify in the data stream, the values ​​marked with the word This is the coolant temperature. After starting the engine with the engine running time of growth and increased, and finally to 90 ° C to 105 ° C operating temperature. If the temperature does not change over time, but the temperature and the actual temperature of the coolant to maintain a fixed value, or the decoder to read out the relevant data sets are different, there may be damage to the coolant temperature sensor or line problems. Such as engine work, when the cooling system thermostat is fully open, the coolant temperature gradually increased, but decreased by several degrees, there may be the coolant temperature sensor is damaged. damage to the common failure phenomena
coolant temperature sensor is:
motive of black smoke;
2 cars is not easy to start;
3 to accelerate bad;
4. unstable idle. sometimes turn off.
, throttle position sensor
throttle position sensor electrical parameters of the engine load calculation parameters. Throttle opening data, the general standard angle symbol, easier to identify. The general approach is to check the throttle position sensor: connect the decoder, turn the ignition switch but does not start the engine, the decoder transferred to observe the screen of the throttle sensor data set, riding slowly moving the accelerator pedal and observe the throttle opening changes, the throttle should be small to large uniform changes in throttle riding in the end, the throttle should be greater than the manufacturers of the provisions of the throttle minimum. And then slowly release the gas pedal, the throttle should be descending the uniform changes, completely release the throttle pedal, the throttle should be within the scope of the manufacturers of the provisions, generally 2-6 degrees, otherwise that may be damage to the throttle position sensor, or line failure. The damage caused by the common failure of
throttle position sensor:
accelerate bad;
idle bad;
3. engine flameout;
4 may also lead to the automatic transmission into the state of emergency.
four the engine air flowmeter
in the engine intake air is another important parameter to determine the engine load. The data in its value after the general units of g / s for easy identification. There are two methods of inspection of the engine intake air: First, whether changes in acceleration and deceleration experiments and observe the value of the intake air in the engine when the engine is running, do not change the air flow meter; observe the idle speed when the feed rate values, common value of 2.4g / 5.0g / s, otherwise the air flow meter or the intake system.
In general, the common fault of the air flow meter flowmeter was dust, dirt, this phenomenon decoder may read less than a fault code, but use the decoder to read the measurement data function can be observed. Dirty air flow meter, the performance data block into the gas value changes in response slow idle intake than the actual feed rate value is too large.
into the air are not allowed often caused by failure:
accelerate bad;
2. tempering;
3 exhaust pipe blasting.
supra tk society, fuel injection the amount
engine fuel injection quantity is calculated by the engine condition by the control unit to the control, usually in numerical ms units in order to identify the fuel injection quantity to reflect the working conditions of the engine and changes. Check the method of measurement data block function in the decoder read and observe the idle speed when the fuel injection quantity, and manufacturers of the specified value for comparison. Such as the Jetta sedan, its value should be 1.3 ms to 2.5ms, the phenomenon of lower than 1.3 ms only in speeding cut higher than 2.5ms tory burch outlets, indicating injector excessive. common cause of
injector excessive:
1. air flow meter is damaged;
2. throttle control unit damage;
3. additional load;
4 in which a cylinder or cylinder number of working poor;
six, the oxygen sensor voltage change
oxygen sensor voltage is the important parameter for feedback control of the engine mixture concentration. Its value is generally The oxygen sensor voltage, check the decoder to read the measurement data measurement, the value should change back and forth between 0-1 volts, the minimum should be lower than 0.3V, the maximum should be higher than 0.6V and less than 0.3 V and higher than 0.6V the frequency is approximately equal. The oxygen sensor voltage in
not common failure:
accelerate bad;
2. towering car;
3. black smoke;
sometimes turn off. The common factors
cause abnormal changes in the oxygen sensor voltage:
1 oxygen sensor is damaged or line failure;
2 intake system leak;
3. air flow meter fault;
(4) the fuel pressure is too high or too low; to
5. nozzle failure;
fuel vapor recovery system failure;
2. exhaust gas recirculation system failure;
ignition system failure.
when the car appears sometimes to turn off or driving in the towering the car
failure, to determine whether the failure caused by a bad oxygen sensor, there is an easy way to disconnect the oxygen sensor wiring harness and hand plug, so that the oxygen sensor The signal can not spread to the engine control unit, then observed changes in the vehicle, if the fault has not changed, this fault is not caused by the oxygen sensor if the fault is changed or the fault disappears, the more oxygen sensor or wiring is damaged. the
seven, the engine the load
engine load sensor parameters calculated by the control unit by the inlet pressure or the fuel injection quantity, directly by the fuel injection ms for units in the general value, or for general use expressed as a percentage of the inlet pressure, 30%, 20%. Generally observe the idle speed when the engine load to determine whether the vehicle is faulty idle when the engine is generally 1.3-4.08ms or percentage of 15% -40%. often the reason of
engine load guide in general:
intake system leak;
2. vacuum tube blockage;
3. gas distribution timing error;
additional load .
ignition advance angle
ignition advance angle value the Model values, please refer to the maintenance manual.
ignition advance angle guide often common reasons:
electrical power;
2. steering wheel is not correct;
3 intake system leak;
idle stability valve damage.