Pu Sang 1.6L idling mixture is too rich. What is the reason?

Causes of gasoline engine failure with too much mixed gas: the main metering hole adjusting needle valve is turned out too much, the oil level in the float chamber is too high, or the main metering hole is worn too much, and the choke valve is closed; The air filter is too dirty or too much oil is added; The float is broken or the triangular needle is not closed tightly; The air hole of the injector is blocked.

The mixture of EFI engines usually does not need manual adjustment. The throttle of Changfeng Cheetah Mitsubishi 4G engine has an adjustable bypass channel, which can not solve the problems of black smoke, jitter and ignition in the engine exhaust pipe. ...

The viscosity of the mixture is only one of the reasons. Since the phenomenon of thick and thick mixing has appeared, it means that the correction limit of the computer has been exceeded, and the computer is powerless. In the case of more fuel and less oxygen, the mixture will not burn completely in the cylinder, and it will also pollute the spark plug (blackening), leading to poor ignition and vicious cycle, which will affect the unstable idle working condition. Only by finding out the cause of the excessive mixture is the fundamental solution to the unstable idle speed. In addition, the detection methods and instruments for determining the concentration of mixed gas are also very important. For example, the common method is to see if the exhaust pipe emits black smoke and the spark plug is black. This phenomenon will occur when the mixed gas is concentrated. In fact, high pressure and weak fire can also happen. Be careful not to misjudge; Because of the performance of oxygen sensor itself, there are some limitations in reading data stream with detector. The exhaust gas analyzer can be used to simultaneously measure carbon monoxide and hydrocarbons. This method has high accuracy. According to the measurement results, the working condition of the engine can be comprehensively analyzed and the fault causes can be found out.

1.ECU determines that the engine is under partial load. At this time, ECU determines the fuel injection quantity according to the air flow meter and crankshaft speed signal. At this time, the engine is idling, and the intake air is less, which leads to the mixture being too rich and the speed increasing. When ECU receives the "rich mixture" signal fed back by oxygen sensor, it reduces the fuel injection amount and increases the opening of idle control valve, resulting in the rich mixture. Reduce the rotation speed. When the ECU receives the signal of "the mixture is too lean" fed back by the oxygen sensor, it increases the fuel injection amount, reduces the opening of the idle control valve, and makes the mixture too rich, thus increasing the speed. Repeatedly idling the engine, turning on the air conditioner, turning on the steering wheel and turning on the headlights will increase the load of the engine. In order to prevent the engine from stalling due to increased load. The ECU will increase the fuel injection quantity to maintain the stable operation of the engine. When the idle contact is disconnected, ECU thinks that the engine is not in idle state, so it will not increase the fuel injection quantity. Resulting in engine idling instability, jitter and so on.

2. Idle speed control valve (ISC) is faulty.

The electronically controlled idle speed control valve ensures the correct idle speed of EFI engine. ECU adjusts the idle speed control valve according to engine speed, temperature, throttle switch and air conditioner signals. When the idle speed is lower than the set speed, the computer instructs the idle speed control valve to open the air intake bypass channel or directly or directly increase the throttle opening, thereby increasing the air intake and improving the engine idle speed. When the idle speed is higher than the set speed, the computer will instruct the idle speed control valve to close the bypass passage to minimize the intake air and reduce the engine speed. Due to oil pollution and carbon deposition, the idle speed control valve is slow or stuck, and the throttle valve is poorly closed. The ECU can't adjust the idle speed of the engine correctly, resulting in unstable idle speed and jitter.

3. The air inlet pipe leaks.

According to the principle of engine idle speed stability control, in general, the opening of idle speed control valve strictly follows a certain functional relationship with the air intake, that is, the opening of idle speed control valve increases, and the air intake also increases accordingly. When the intake pipe leaks, the intake air volume and the opening of the idle control valve will not strictly follow the original functional relationship, that is, the intake air volume suddenly changes with the change of the idle control valve, and the air flowmeter cannot measure the real intake air volume, which leads to the inaccurate control of the intake air volume by ECU, which leads to the engine idling instability and jitter.

4. The throttle valve is not closed correctly.

When the engine is idling, the throttle valve is closed (bypass air idling control type). If the throttle valve is not closed tightly at idle speed, resulting in air leakage, ECU can't control it. As a result, the air intake of the engine is large, the VS signal of the air flow meter is increased, and the ECU increases the fuel injection quantity to increase the speed. However, at this time, the idle contact (IDL) of the throttle position (TPS) is still in the closed state, and the ECU supplies oil according to the idle program according to the IDL signal, so as to reduce the fuel injection amount and speed. Resulting in engine idling instability, jitter and so on.