Resetting Long Term Fuel Trims
WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
Long term fuel trim corrections can be reset by resetting the PCM keep alive memory (KAM). Refer to RESETTING THE KEEP ALIVE MEMORY (KAM) . After making a fuel system repair, the KAM must be reset. For example, if dirty/plugged injectors cause the engine to run lean and generate rich long term corrections, replacing the injectors and not resetting KAM, now makes the engine run very rich. The rich correction eventually is learned out during closed loop operation, but the vehicle may have poor driveability and have high CO emissions while it is learning.