Elimination method of over-diluted mixture

Too lean mixture means too much intake air or too little fuel injection. The main reasons are: air leakage in the intake pipe, air leakage assisted by brake vacuum, mechanical failure of throttle valve, and sensor misreporting data. Check the air leakage first, and block the brake vacuum tube and carbon canister vacuum tube. If the fuel correction data is still thin and unchanged, spray cleaner on the intake manifold. During this period, if the data changes, the fault point is the air leakage where the data changes. If there is still no change, spray cleaner at the air intake (throttle). If the speed increases, it is a throttle problem.