Hi, my friend and I bought matching ecoboost mustangs about 9 months ago, and bought the Ford Performance calibration kit and had a dealership install them. Right when they were installed, we could feel the extra power it gave them. Also, after the install of the calibration, both cars would make a noise/knocking right when we would let off the accelerator sometimes. We figured this was normal, because both cars did it right after the install. About a week ago, my mustang stopped making that noise and the extra power from the calibration isn't there anymore. Now, today, my friend's mustang has stopped making that noise and the extra power is gone now too.


I don't know what the noise is, if it's flaps or valve noises, and I don't know why that's related to the power from the calibration. Any idea what that noise is and why the calibration power has vanished?

 

Maybe the calibration expired?