I have B16A engine with lightly modification.My question is with the stock fuel pressure (stock set at 36 Psi) the engine I think running rich.Because I just drove the car for 10-15 miles and the sparkplug ring became black already.Now I install SARD fuel pressure regulator,what about if I reduce the fuel pressure setting (for example to 30 Psi) will this help my car, so not running rich? thanks.

 

Whats all done to the motor?
Stock injectors?
any codes? cel
If all you have is a few bolt-ons, no cel's and the rest is stock I seriously doubt your running rich. Find out for sure before you start messing with the fuel pressure, otherwise your little "experimentation" may cost you a lot more then you expected.

 

Well,my modification is intake,header,exhaust,MSD SCI ignition,Crane cams PS91 coil,SARD fuel pressure regulator,spoon sparkplug cabel, and denso iridium IK20 sparkplug.Before I change the fuel press regulator this already happen, even I use a standard sparkplug. So do you think this is normal? I mean the car is running fine no cel's at all. How many PSI I should set my fuel press considering my modification then? thanks.

 

36-40psi sounds about right.
Without seeing the plugs personally I'm going to venture to say that they are probably normal.

 

Ok,thanks. Do you think it is cause by colder sparkplug? Because according to Denso it should use 1 step hotter (IK16). Do you think it matter?

 

Just use the stock temperature plug. If you are currently using colder than stock, that may be your problem.