What is the reason for the black smoke from the cold start after the regal oil channel cleans the throttle?

Check for loose parts and oil leakage. In addition, cleaning the throttle valve does not help the oil circuit and nozzle. If there is blockage and uneven oil supply, it may burn badly and emit black smoke. At the same time, if the engine has more carbon deposits, it may also emit black smoke. You can try to improve the combustion by using the efficient fuel additive Mafudou tablets.