I have a 1998 civic ive been working on at my shop, it had a turbo swap in it and we removed it and turned it back to NA with stock computer etc, runs great but after a day of driving threw a cel for running rich, used a new fuel pressure regulator and still it ran but when you were driving you could feel it surge, replaced one 02 sensor and still, i swapped the other and when im driving there voltage reading isnt very high, the first one is no more then 1.5v ever and the bottom rarley sees .5v im so lost, yes they fluctuate but not much, and its blowing black when you punch it, anysuggestions? what could it be any help would be much appreciated

 

Do you have a 255lph pump in it? I have personally never driven a stock car with a larger fuel pump, but I would imagine it might make it run richer

 

would it still do that even though the computer is controlling the fuel flow?? i mean it will only let in so much fuel no matter what? i dont know if it had a bigger pump or not but i guess i have to drop the tank and see, i can get a stock pump from the junk yard..