Has anybody compared fuel mileage before and after changing fuel pressure? What psi and mpg before/after?

 

On a mostly stock L98, I gained 1 mpg by turning the pressure up from 43 psi to 49 psi

 

Gained? I'm not doubting you, but the logic evades me.

 

Once the car is in closed loop the o2 sensor controlles A/F ratio. Now technically changing fuel pressure should not affect the MPG as long as the block learns are off 108 or 160. Now increasing the fuel pressure can help in atomization, so they say, so maybe that had something to do with it...I dont know.

Now if your cruising around in PE all the time, or you dont have a closed loop system (GM ramjet pos) fuel pressure will have a lot to do with your MPG.

I put on a Set of Taylor wires and some brand new platnum plugs in my F150 and i gained 1 mpg....thats not a lot to some people, but whe you drive as much as I do and you only got 14 to start with....its alot.

Take care,

Erik

 

Can you explain the above?

 

When the computer sees 108 in the BLM, its compensating by dumping too much fuel into the engine and at 160 its not dumping enough (i.e. a lean condition). When you tune your car yourself, you can "invoke" highway fuel mode and get some killer gas mileage by running the Air Fuel ratio higher than 15... some crazy people go all the way to 16 if they can get it to act ok. 30mpg I wish I needed highway fuel mode, I'd turn that bitch on with gas prices the way they are, but I don't get much highway driving in.