How is it that the throttle of dl250 has a heavy smell of exhaust gas and gasoline after cleaning?

After cleaning the throttle valve of dl250, the specific reasons for the heavy smell of exhaust gasoline are as follows:

1, poor fuel quality: gasoline contains too many impurities, heavy metals, moisture and so on. , causing the exhaust gas to stink.

2. Incomplete combustion of mixed gas: The main reason for insufficient combustion of mixed gas is that the mixed gas is too rich. On the one hand, it will produce a large number of carbon monoxide and free carbon particles in the cylinder, which will affect the purification ability of the three-way catalyst. On the other hand, some mixed gases that are not involved in combustion will also be discharged with the exhaust gas, which will aggravate the smell of the exhaust gas.

3. The three-way catalytic converter is faulty.