What to Do When a Diesel Car Emits Black Smoke?

[DiHenry]

Solutions for diesel cars emitting black smoke: 1. Remove the air filter and observe the exhaust smoke color. If the black smoke condition improves, the fault is caused by severe dirtiness of the air filter; 2. During engine operation, conduct a cylinder-by-cylinder fuel cut-off test. When a certain cylinder is cut off, if the engine speed decreases, black smoke significantly reduces, and knocking sounds weaken or disappear, it indicates excessive fuel supply to that cylinder. If the engine speed changes little and black smoke disappears, it suggests poor spray quality of the injector in that cylinder; 3. Check if the fuel supply timing is too early. If it is, adjust it accordingly. After identifying the faulty cylinder, disassemble and inspect the injector. If necessary, replace it with a new injector for comparison. If the fault disappears with the new injector, it indicates a problem with the original injector.