i had a same problem for the injector of cylinder not working get it checked it could cause troubles later the problem with mine was the vales of 1 cylinder were bent so the car was only driving on 3 cylinders and if your vales for the cylinder are bent or burnt get them from Toyota don't get the Desi ones they will create a tik tik tik tik tik type sound but first i will say get it checked by a good w.shop .
Thanks for all for taking interest & suggestion in my car's problem.
itsstyle : I have already checked it from toyota w/shop they told my injection is not working & new injection price is Rs. 7500/- ( I found injection in shersha it it Rs. 1500/-) & 2ndly they told about tapped we have to open head to fix the tapped problem. (Actually my car is making so much sound from engine side & in specially 1st 2 gears have missing very much)
ali_sumair1 : I have already changed the spark plug but still facing the problem.
Ghufrandurez : fixing the tapped problem in xli is not a simple job as the other cars which comes in company fitted cng 4 this purpose head will be open & budjet goes between Rs. 4500 to 10,000 (any ways can u advise me any workshop in karachi to fix this problem)