What happened to Sophie's engine?

The reason of unstable idle speed is 1. The first cause of air intake system ① is the leakage of air intake system, air intake pipe and various valves. Air enters either from the intake pipe, gasoline vapor enters from the carbon canister valve, and exhaust gas enters the intake pipe, which will cause the mixture to be too rich and too thin, which will make the engine burn abnormally. ② There is too much dirt on the throttle and air inlet. ③ Inaccurate intake at idle speed. 2. Fuel system ① Fuel injector failure. If the injector leaks oil or is blocked, it can't inject oil according to the instruction of ECU, which will cause the mixture to be too rich or too thin, make individual cylinders work badly, and lead to unstable engine idle speed. ② Fuel pressure failure. If the oil pressure is too low, the fuel sprayed by the injector is in poor atomization state or the fuel sprayed is linear. In severe cases, only oil droplets are sprayed, and the fuel injection quantity is reduced, making the mixture too thin; When the oil pressure is too high, the actual fuel injection increases, making the mixture too rich. ③ The fuel injection quantity is inaccurate. The fault of each sensor or line causes the control unit to send out wrong instructions, which makes the fuel injection amount incorrect, and the mixture is too rich or too thin, which is the indirect reason for the unstable idle speed. 3. Ignition system At present, almost all cars integrate the ignition module with the ignition coil, or use double ignition coils or direct ignition. First of all, the ignition module, if its failure will make the spark too weak or fail to catch fire, can only say that there is no vehicle for measuring the excitation voltage in the voltage, but the ignition trigger signal can be measured. The ignition coil and the ignition module may be caused by insufficient ignition signal from the computer, or the power supply circuit of the ignition module, etc. In actual maintenance, this happens from time to time. It is very likely that a new car will appear. When we repaired a new car, some repairmen still looked around and found many problems. For a new car, we still need to ensure its power supply, positive and negative poles and make it run reliably. 4. The first mechanical structure is the valve train. The failure of the valve train causes the power of a single cylinder to drop too much, which makes the power unbalanced. Secondly, there is too much carbon deposited on the valve working face and valve seat ring, which leads to the lax sealing of the valve. The third is the engine and piston connecting rod mechanism. If it fails, the compression pressure will be inconsistent. 5. When the exhaust system is blocked and the inside of the three-way catalytic converter is partially blocked or randomly blocked due to glue, carbon deposition, damage and other reasons, the back pressure during exhaust will increase, which will make the vacuum degree of the intake pipe too low, resulting in incomplete exhaust of the engine and insufficient intake, resulting in poor working performance of the cylinder. The engine wobbles at idle speed. Poor air intake may also cause the computer to remember the fault code of the air flow meter. If the fault is not eliminated for a long time, the oxygen sensor will work in harsh conditions for a long time, which will accelerate the damage of the oxygen sensor and lead to the engine fault light.