start of below to find the problem.
1) remove all CNG related wiring and equipment. disconnect it completely.
2) remove fuel pump from tank and clean its sock type filter, also replace the inline filter in the engine bay.
3) from the fuel tank fill line to the engine fuel rail. trace the fuel lines and find out if any leakage present.
4) remove the injectors and have them ultrasonic cleaned. they must not be leaking and must have proper spray pattern. when replacing them, use BRAND NEW o rings
5) remove any air blockages. and find out any leakages in the air inlet system. there must not be any leakage after the air filter upto the throttle body.
6) check and calibrate and clean the throttle body. check the throttle position sensor
7) check and clean the MAF sensor if equipped. this must not be cleaned by petrol. i am not sure this sensor is available in this car. its not available in my d15 non vtec exi civic. it has a simple air temp sensor.
8) these wheels are incorrect for this vehicle, but will not effect fuel efficiency by much. however you must have your car properly wheel aligned from all 4 wheels. max size you should get would be 185 / r14. i personally use 185/70r13.
9) is the AC compressor taking too much load? there is a possibility it is seizing up. you will have to change compressor.
10) make sure there are no loose pipes, exposed air inlets/missing vaccum hoses etc.
11) service your distributor, replace plug/wires if needed. use ONLY BRAND NEW GENUINE PARTS. have the engine timing checked. infact have the timing belt replaced if history is unknown. you will need to get GENUINE timing belt, tensioner bearing, MAIN CRANK PULLEY BOLT (BRAND NEW VERY IMPORTANT, OLD BOLT MUST NOT BE REUSED) crank pulley bolt MUST BE TORQUED with a TORQUE wrench. not ANDAZA.
