What is the reason why the old Bora cold car does not idle at high speed?

1, engine jitter caused by spark plugs and cylinder lines

The larger the gap between the anode and cathode of the spark plug, the smaller the surface area of the ignition point, which leads to the decrease of ignition energy required to compress the oil-gas mixture, which leads to the decrease of power, affects power and makes the automobile engine shake. In addition, the aging of the ignition coil may lead to poor flow or leakage of high-voltage electricity, and may also lead to unstable idle speed of the engine and jitter due to power reduction.

2. Engine jitter caused by oil-gas mixture ratio

This phenomenon is common in old carburetor cars, but problems with the computer of EFI cars will also occur. The reason is simple and easy to understand. I learned the working principle of internal combustion engine in junior high school, so I don't want to go into details here.

It is worth mentioning that the oxygen sensor is installed near the root of the engine exhaust pipe in the current EFI vehicle, which is an important parameter for the driving computer to control fuel injection. In closed-loop controlled vehicles, the minimum working temperature of the oxygen sensor is 370 degrees Celsius. If the temperature in the exhaust pipe is lower than 370 degrees Celsius just after the vehicle is started, the oxygen sensor will not work, which will cause a temporary judgment error of the driving computer, resulting in an error in the control of oil-gas mixing and ignition time through the actuator.

3, valve, throttle valve and idle valve carbon deposition lead to jitter.