my friend has a 00 civic si and he says lately he has noticed that it is running rich and he wanted to know how to fix that or what he needs to do. dont know what else you need to know about the motor it has the basics i/h/e nothinfg has changed on the fuel system. thanks any info would work

 

How does he know it's been running rich? Has he pulled the plugs? That's the only real way to tell how the motor is running. If he is running rich, I would change out the plugs, wires, etc. Give the car a little tune up. Check timing. For best mpg on the EM1, have the timing set around 16. More infor will be needed for a more specific answer.