Why does the cab still smell of exhaust after the car has cleaned the throttle and nozzle?

There are many reasons for the heavy smell of gasoline, such as fuel vapor leakage caused by the blockage of carbon canister and solenoid valve, slight leakage of fuel delivery pipeline or poor sealing of fuel tank cover, poor performance of ignition system, insufficient combustion caused by oil leakage from nozzle, and low three-way efficiency, all of which will cause problems in automobiles with heavy smell of gasoline. Ask the car master. 4S shop professional technician, 10 minutes to solve.