4th ma tw low compression b krty bhai, ma 2nd ki bat kr rha 2nd ma b 1400-1700 rpm ma knock krti ha, waja compression ratio ne ha, agr aap light sa b paddle rkho tw it won't knock lekin agr paddle chorr k re accelerate kro gy tw it'll knock(aap k pas tw gari mojoud ha, experiment kr k dekhna), reason ya ha k sb new efi cars accelerator lift off krny pr agr clutch depress na ho tw fuel cut off kr deti till speed becomes low enough that fuel is required to keep the engine running. swift does that at around 1400-1700 rpm unlike other cars which do that at lower rpm and more smoothly.