OK, so since the car was working fine so I thought I'd hold on to the idea of zero-point calibration but a new (perhaps unrelated) problem popped up. The car turns off with the AC on when it stops to zero (after being driven) and there is a very weird knocking sound (metal clanging) from under the bonnet too. It started with the first time car swtiched off on a speed braker. Also I should mention the car doesn't start in a single easy ignition but the car keeps trying (as if I were forcing the key to remain turned) and then starts up in like 10 seconds. With AC turned off, the metal clanging sound is there but car runs smooth and also starts up in a single ignition.
I think the biggest problem with my car is AC. Does anyone know a good mechanic for Vitz in Karachi who knows what he's doing? I'm not that big a techie plus I don't have a lot of time for diagnosis...