Comparison of Air Meter Interface Strategies for Engine Management Systems
When an air meter is specified for an engine management system, air meter accuracy is given high priority. Air meter manufacturers characterize the accuracy of their products using laboratory instrumentation to measure the air meter output vs. flow characteristics. Ultimately the air meter is applied to an engine management system in a vehicle. The engine management system must use the information provided by the air meter without the benefit of laboratory instrumentation. Therefore, the entire measurement system must be considered in evaluating the effective accuracy. The most fundamental aspect to consider is the output signal format between the air meter and the engine management system. Two commonly available formats will be investigated: frequency and voltage.