Why does the Jiefang J6 emit black smoke when shifting gears and accelerating?

[DeGrant]

The reasons why the Jiefang J6 emits black smoke when shifting gears and accelerating are as follows: 1. Incorrect ignition timing: This can also cause incomplete combustion of the air-fuel mixture; or if a few cylinders in the engine are not working, a small amount of black smoke may be emitted. The non-working cylinder can be identified using the cylinder cut-off method, or the ignition timing can be checked and adjusted. 2. Overly rich air-fuel mixture: This means the air-fuel mixture in the cylinder has an excessively low air-to-fuel ratio, leading to incomplete combustion. Some fuel decomposes into free carbon at high temperatures and is expelled through the exhaust pipe, forming black smoke. It is necessary to promptly check if the choke valve is fully open and, if needed, perform high-speed maintenance.