i just did a b16 swap in my honda and its running really rich..why?

 

What makes you think the engine is running rich? Do you have a CEL?

Information supplied from the primary O2 sensor to the ECU functions to determine proper air/fuel ratios.

 

It's running real bad on gas mileage. Yes, the CEL is on.

Information supplied from the primary O2 sensor to the ECU functions to determine proper air/fuel ratios.

I'm not exactly sure what your talking about. Could you put it a bit simpler?

 

The computer reads the O2 sensor to determine if the engine is running rich. If it is it tries to reduce the fuel mixture. If that is not successful it sets a code and turns on the CEL.

Make sure the little vacuum hose on the end of the fuel pressure regulator is hooked up properly. If not you will have too much fuel pressure and a rich condition.

 

Retrieve the CEL code yourself as detailed here:

http://www.honda-tech.com/zerothread/1901557

Clear the CEL code and verify that the same code(s) is again thrown. Troubleshooting repeated codes should reveal the reason for your poor gas mileage, which I suspect will be due to a fault in the primary oxygen sensor system.

 

get the CEL codes and tell us what it says

 

Yes if the sensor is bad it will also run rich and turn on the CEL, but with a different code than if it is rich for some other reason.