Does My Car Engine has a vacuum leak?, Vitz 2005-06

[riztauras]

Hi,
So I am having bad fuel efficiency and low power issue on my Vitz 2005 compared to other similar Vitz.
What I did is I tried to completely block the air from Air filter box intake as circled in the picture, this had absolutely no effect on engine rpm, does it mean I am having vacuum leak problem?

[FaatehRehman]

Try this method with a CNG car first to see quick feedback, and secondly just block it off with some electric tape properly and then try to drive the car for some 500 meters or so, you will surely see the difference.