^^ Its Called O2 Sensor...And Its Will Happen if Its Broken And Fixed Again...!
@Asad........You HAVE JDM Model AE110 So You Don't Have Variable Resistance...You Have O2 Sensor...I Am 80% Sure..Its Busted....
2ndly....In Diagnosis Box....All You Need Is To Short TE1 And E1 W/o Touching Everything Else......Trust Me...Nothing Happen If You Do It Correctly...... But Short These Two Jumpers And retrieve Error Codes....
BUTT
If You Are Not Sure What To Do.......Get Some Help ...!
ECU's Won't Blow Like This But We Don't Need Blown ECU Anyways......
8km/L is Not A Bad Considering Auto And All factors....Get O2 And All Checked And Replace And Set Timing With GUn And It Will run Happy..So Many Factors Involved Like Xulfiqar Said..It Can Be Injectors Clogged or Low Fuel Rail Pressure....
No Need To Mess With Tappets For Now....!!