Recently, a car owner asked "the air quality is too high". Today, I will take you to have a detailed understanding of this problem. This problem is usually caused by the "emission warning lamp" on the instrument. The following fault code is saved in the DME: 102001: "air quality, reliability: too high air quality".
First of all, why do you see this mistake
BMW's air quality measurement is no longer directly measured by HFM (air flow sensor), but by DME (engine computer) through intake valve lift (throttle valve position), VANOS position, intake temperature, engine speed, intake pipe pressure, ambient pressure. These six signals are calculated synthetically.
However, HFM also measures air quality, and if the difference between HFM data and DME data is large (usually more than 40%), a "low air quality" or "high air quality" fault is reported.
Data measured by HFM < data calculated by DME, reported as "low air quality".
Data from HFM measurements, > and DME calculations were reported as "too high air quality.".
PS: in case of engine idling and emergency, the intake air is regulated by throttle valve.
2、 On the cause of fault
Based on the above analysis, we know that the common causes of "excessive" air quality are either unit problems, resulting in too large measurement data, or calculation problems required by 6-signal ranging device, resulting in too small calculation data, or problems of direct ranging device, as follows:
1. HFM (air flow sensor) failure;
2. Air intake system
A. Air intake not sealed / leaking.
Electronic valve system fault: such as eccentric shaft sensor, VVT, etc.
C、 VANOS system fault: such as camshaft sensor, crankshaft sensor, etc.
The throttle position sensor is faulty.
E. Inlet temperature sensor failure.
F. Inlet pipe pressure sensor failure.
G. The ambient pressure sensor is faulty.
The intake muffler and the air cleaner element housing have geometric tolerances.
3. DME system application.
4. Circuit problems between related sensors, control system and DME.