Aamir bhai you surprise us every other day with your vast knowledge & hidden talents (A). You are a true genius indeed. We LFC people are lucky to have experts like you on board.
As far as the car is concerned, it looks fine now. I test drove it, there is no backfire at all. As per my little knowledge, I it tested coils by applying load on coils. First of all I parked the car & then drove it in 1st gear, no backfire at all. Then I parked it again & deployed 2nd gear directly & made the car move with heavy throttle & slightly pressed clutch, No patakha, no misfire, everthing was OK. Then I did the same with deploying 3rd gear directly, again no misfires. Then I tested drove uphill & again no problem, so I was satisfied. Yes the engine was less responsive which I assume is due to disturbed CNG adjustment. I feel k CNG ka ziada gala daba diya hai mechanic ne. Rest engine is smooth.
I will check the spark next time when I open the plugs. I am also planning to purchase a tool kit for myself & then I will tune it myself. Especially, mechanics put a standard gap in plugs usually 70mm for all 1300cc cars which is not good. Liana needs something at 75mm & once I even tried 80mm too & fuel economy was just awesome with very smooth drive.