Calibration of idling characteristics for Lemon Peel Oil using Central Composite Design in light commercial vehicle diesel engine

•Systematic calibration of engine idling is performed for LPO biofuel.•CCD and RSM technique is used to calibrate the engine idling condition for diesel and LPO.•LPO improves combustion quality, reduces CO & Smoke with minor surge in CO2, NOx.•Lower calorific value slightly reduces engine performance and HC rises significantly.•LPO-diesel blend is a vital key to overcome drawbacks caused by idling.