VX was repaired. Lots of adjustments made. MGPS question.

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Ok so my VX was repaired and mechanic said that keyway was bad and cam shaft and timing adjustments of firing were adjusted. Prior to repair compression on cylinders was low and way off so that's good now. Car runs but all those adjustments now made me nervous that my MPGS will suffer. Is lean burn tied in any way to what i just mentioned? Can those adjustments cause now my VX to be making CX or EX mpgs instead of VX mpgs? Any mechnics or people that know how can tell me if all the fixes can possible threw off mpgs now? Is mpgs or lean burn only tied to ECU (computer) and oxygen sensor only? I'm freaking out now.