everyone
Recently, my car average has drop to 7-8 km/l irrespective of city or highway. I was getting around 10 in city and 14 on highway. Car is manual. I Already serviced the throttle body etc and changed the spark plug by reputable mechanic. Average got better for like 500 km and then dropped to it's previous stage. The air fuel ratio is above 3 after scanned(should be around 2.3 according to mechanics). Any idea what's the problem is. Some are saying that absence of catalytic converter is the problem. But internet is saying otherwise. Kindly shed some light as i Don't want to get rip off by these mechanics by going there blindly.
