Back fire at idle

[dsmtalontsi95]

What would cause the car to back fire during idle? I have a 97 w/bolt swap, 660, and 255 fuel pump with fpr and afc. It has a hard time starting but when it does it back fires and sputters. I have ngk8es in it. We have spark and fuel. The afc is set to -35.

 

[spoonman]

You are running rich, try adjusting your FPR to less pressure and try to lean out your AFC then start it and see if it changes.

 

[DSMULATOR]

Check to make sure your fuel pressure is 44 with vacuum disconnected. Well 43.5 if you want to be particular, but I haven't found a gauge that accurate....