running rich/lean means the sensor input/output and engine as its designed to work is not syncing
its running lean /rich on diff revs as per diff fuel maps..else plugs would be ultra black but its only running rich ...means the fuel variation condition is there
the point of emphasizing to use its own ecu is 1st the NVCT which is mandatory for smooth engine operation.
right now the engine is just QG13 with 1.8L Displacement...!nothing else.
the performance difference you see is due to that massive displacement difference in both motors..
as per sensor input..rich/lean condition arise and both are bad for engine health...
kabariya/scrapia never hand over the correct item nor they know and care abt the importance of it..for them its just a piece of chip with fixed cost! this is why i always prefer motors with complete wiring/ecu and upon not finding one....hunt for atleast ecu of desired motor as wiring can be manipulated but ecu cannot!