99proES

or will the ecu just over write it??

The reason i ask is cause i got slow, slow take off ( i have automatic) and wanted to know how i could get it to launch faster.

99proES

so if i put an intake on my car it won't need more fuel pressure? I mean i am getting more air so won't i need more fuel??

99proES

ok thanks

Traveler

It will richen your mixture slightly. The fuel pressure being higher will still tend to override the computers attempts to lean up the mixture since the computer will only be able to shorten the pulse width to a certain point.

The other thing that it will tend to do is keep the engine from going lean if you do a bunch of other mods. Bumping the fuel pressure up has been being done by the 5.0 Mustang guys since almost day one. It helps to overcome the ability of the injectors to flow at higher rpm. By bumping the fuel rail pressure higher, the injectors are cycling less fully and don't reach saturation as easy. Saturation point is where the injectors are cycling so close to the factory flow limit that they basically go to constant flow. When that happens all control over mixture is lost. The next step after that is usually a better fuel pump and bigger injectors.

I've been looking into an adjustable regulator for our cars and am probably going to experiment with one when I get a better muffler on my car. Since I found a place that has a dyno, I'm going to run the car at the stock pressure and then bump it up a couple of pounds and try it again. Then a couple more for the third pull. Will see what it does. The place that I found with the dyno lets you have 3 pulls for $75 and you can do tuning in between as long as it doesn't take very long. Where is the best place to get an adjustable regulator for the FS engine?

Traveler

If you put on a header, better exhaust and better intake, it usually leans things up. If the computer can't richen it up enough to compensate due to it being too much out of factory settings, bumping the fuel pressure up a couple pounds may do the trick. The only way to do it properly however is to use a dyno and some kind of O2 sensor that gives you A/F ratio. You usually start at stock and then bump it up 2 lbs at a time until you get the best power without being too lean. 14.7 or leaner works at cruising, but you want closer to 12.5-12.7 under load for best power and engine life.