What is the standard air flow rate at idle?
2 Answers
The air flow signal data at idle is approximately 2.5g/s. Below is relevant information about idle air flow: 1. If the air flow at idle is less than 2.0g/s, it indicates an air leak in the intake system. If it exceeds 4.0g/s, it suggests additional load on the engine. The normal air flow value varies for each engine, with larger displacement engines having higher air flow values. 2. The air flow signal is one of the primary signals used by the engine control unit (ECU) to regulate the air-fuel mixture concentration. If the intake air volume increases, the ECU increases the fuel injection accordingly, and vice versa. 3. The air flow sensor signal is a key basis for controlling the air-fuel ratio. Therefore, an infrared exhaust gas analyzer can be used to measure the exhaust components during engine idle and stable operation at 2000r/min. If the readings deviate significantly from standard values, it is likely due to poor performance of the air flow sensor.
I've been driving for over 20 years and have seen many cases of unstable idling. I remember my old sedan once shook like an earthquake at red lights, and it turned out the idle air flow value was abnormal. A professional mechanic told me the normal range is between 4 to 8 grams per second, and my car measured 6 grams per second at that time. After cleaning the mass air flow sensor, it worked fine. He explained that if the value is too low, it indicates blockage, and if too high, it means air leakage – both affect combustion efficiency. Now during every maintenance, I have them check it, especially replacing the air filter when it's dirty to prevent problems. Experience shows that for regular family cars, values between 5 to 7 grams per second are ideal, but it depends on engine size. Regular maintenance is recommended to ensure smooth operation.
