how bad is it if you are running rich? i heard that the preludes come running rich fromt he factory so you should get a VAFC, so then that means that running a little leaner would help? i am confused.

 

Running rich means you waste gas, the motor runs cooler, and not to it's power potential. Running lean can damage your motor.

 

so if i got a VAFC and made it run alittle leaner, that would give me more power and i would save gas? becasue every time i hit vtec, the gas goes down noticably.

 

Well, I ran a thread about my d16z6 running too rich and some tried to say that ... no fuel---no power ... and that more is better . There is definatly is a optimum air fuel mixture. It all depends on if you can burn it or not . If you cant, then the space that the unburned fuel is occuping is useless. Replace tha extra fuel with air, and the mixture will burn more efficently. Just remember that if you are going to tune on the edge which is close to lean-----Heat kills


It's always good practice to look at your plugs. Black is fouled - white is too lean. Most shop manuals have colored examples.
Hope I helped -

 

When you start playing with the fuel curves you really should do it while the car is on a dyno. There is a lot of room for messing things up more than you'd like.