Resetting Long Term Fuel Trims
Long term fuel trim corrections can be reset by resetting the powertrain control module (PCM) keep alive memory (KAM). Refer to RESETTING THE KEEP ALIVE MEMORY (KAM) . After making a fuel system repair, reset the KAM. For example, if dirty or 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.