Hello i own santro plus 2000 and i am from karachi my concern is i have problem with my vehicle from last 8 month the fuel average is very bad its around 3km/liter  on an average i have check with mechanic or electrician many time but the issue is still there last time when i check with mechanic my vehicle was throwing black smoke with then mechanic change map sensors and choke sensor and smoke disappear for a week then again throwing white smoke and engine also warming up please help me what to do ?