Failure phenomenon
The amount of C0, HC, NOX and other harmful gases emitted by automobiles is larger than that of O2 and CO2 in the exhaust gas, which is required by automobile design. Exhaust emissions may be only one of the excessive emissions, there may be two or more than two kinds of exhaust emissions exceeded.
Two, exhaust emissions exceeding the common causes
1 common causes of excessive emissions of HC compounds
The emission of HC is higher than the normal value may be caused by one or more of the following conditions:
(1) ignition system ignition or ignition energy is insufficient, resulting in mixed gas combustion is not sufficient, should check the ignition system.
(2) ignition time is not accurate, check or adjust ignition timing.
(3) the mixture is too thick or too thin, the content of C0 and O2 can be used to determine whether the mixture is too thick or too thin; the fault of the sensor of the electronic control system or the failure of the computer (PCN) can lead to the mixture too thick or too thin.
(4) the cylinder seal is not good, check the cylinder compression pressure is normal.
(5) the valve timing is not correct, check and adjust the valve timing.
(6) three yuan catalytic converter failure, repair or replacement when necessary.
(7) there is a fault in the two air injection control system.
(8) the fuel evaporation control system can not work properly, resulting in the mixture is too thick.
2 C0 emissions are too common reasons
(1) the mixture is too thick, check whether the air filter is dirty, check the pressure of the fuel system, the performance of the injector, test the input sensor data, check the operation status of the fuel injection control system.
(2) where there is a leak in the injector, test the tightness of the injector.
(3) the three way catalytic converter fault exists, replace if necessary.
(4) there is a fault in the two air injection control system (such as always counter flow into the air).
(5) the fuel evaporation control system can not work properly, resulting in the mixture is too thick.
(6) the PCV system is faulty, the cylinder is mixed with too much gas, or the oil is polluted by the fuel.
3 NOX emissions are too common reasons
(1) EGR system can not work properly, as the case of repair.
(2) check the ignition advance angle and ignition timing control system.
(3) the failure of the input sensor leads to the dilution of the mixture.
(4) in combustion chamber of coke, check the engine compression, to see whether the result is higher than the prescribed value.
(5) Baotou beiben heavy truck parts work the engine temperature is too high, the observation instrument of fault diagnosis of the engine temperature is normal.
(6) the intake temperature is too high, should check the air conditioning system, turbocharging system etc..
(7) check valve timing, valve clearance, variable valve timing system, etc..
(8) Baotou beiben heavy truck parts engine supercharged air intake is too large (such as exhaust gas by-pass valve in the closed position card etc.).
4 O2 readings are lower than normal, and C0 readings are higher than normal
This situation is generally due to excessive concentration of mixed gas, should be mainly to check the reasons for the excessive concentration of mixed gas.
(1) Baotou beiben heavy truck parts injector failure, check whether the fuel injector sealing, resulting in fuel leakage.
(2) the fuel pressure is higher than the normal value, check the cause of the fuel pressure is too high (if the fuel pressure regulator is damaged).
(3) the fuel injection system is faulty, check the sensor and engine control module.