How to deal with the unqualified air quality of BMW?

BMW reports that "the air quality is too low" is a common problem. Before the fault is detected, the car generally has the phenomena of unstable speed, decreased power, no acceleration force and easy flameout. In order to explain in detail how the air quality of this BMW is too low, how the fault happened and why the air quality of BMW is too low. On the other hand, why BMW, which has "low air quality", does not directly measure the intake air quality with a flowmeter, but uses a digital engine servo control system (DME) to measure the intake valve lift, VANOS position, intake air temperature, engine speed and intake pipe. However, the air mass flowmeter also measures BMW thermal mode. When the air quality measured by the flowmeter differs greatly from the air quality calculated by DME, a fault will be reported. Reasons for BMW's low air quality: 1. The air filter element is polluted, damaged or improperly installed, and the air intake may be reduced due to the problem of the air filter. Under the same conditions, the air quality measured by flowmeter is different from that calculated by DME. 2. The air mass flowmeter is damaged, which makes it impossible to accurately measure the air quality. 3. Throttle carbon deposit. Throttle opening increases with carbon deposition, while actual intake decreases with carbon deposition. The air quality measured by flowmeter is quite different from that calculated by DME. 4. The harness and plug between 4.DME and flowmeter are damaged or have poor contact. 5, all kinds of leaks, some air without flowmeter measurement. Common ones are: valve cover, intake manifold, carbon canister solenoid valve, crankcase ventilation valve and crankshaft oil seal. 6, DME control program failure.