Low Idle Air Flow Test
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2009 Mercury Mountaineer, 2009 Mercury Milan, 2009 Mercury Mariner, 2009 Mercury Grand Marquis, and 2009 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
When the cold start emission reduction monitor is enabled, the powertrain control module (PCM) commands the idle air control system to increase the RPM, which elevates engine air flow. While this cold start emission reduction elevated air flow is requested, the low idle air flow test compares the measured idle air flow from the mass air flow (MAF) sensor to the commanded idle air control strategy. For the purpose of detecting low air flow concerns, the low air flow test uses the measured air flow and the commanded air flow to create a low air flow index.