cant quite understand how...

[garfer03]

the fuel system compensates for higher boost. I'm normally used to n/a cars that you have to add on an addiontal computer for fuel, and program it yourself. am i missing something here or is it just as simple as people make it out to be, where you can turn up the boost (as far as stock parts go) and the fuel system will automatically compensate for it? that just seems too damn simple.

[Pineapple]

There is a pressure regulator on fuel rail. Stock one is fixed and connected to manifold vaccum for minor adjustment. Easy way to adjust fuel for NA is to swap the stock one out with adjustable aftermarket one. The regular will reduce fuel pressure at vaccum and increase at boost. Of couse you'll still get better tuning with ECU reprogramming. Its easier to get it tune with both.

[JekylandHyde]

The factory fuel pressure regulator is a 1:1 regulator.
It has a vac/boost line going to the intake manifold.

For every 1 psi of boost, it adds 1 psi of fuel pressure.

Once you get over 260-270 rwhp or so, you are going to want an adjustable FPR that is still 1:1 so you can change the base-idle (static) FP.

See here:
www.trueleo.com/fpr.htm

[garfer03]

so the fuel pressure regulator raises the fuel pressure in the fuel rail to compensate for the addiontal boost? and i was referrig to the 3s-gte engine

[Dirk]

Also, understand that the ECU for the car 'understands' boost, where the ECU for a N/A one doesn't. So, when boost starts to build, the ECU knows it has to add more fuel, and takes care of it.

The reason people add rising rate pressure regulators when they turbo/supercharge an N/A car is to force more fuel through as the boost pressure rises, because the ECU in the N/A car has no idea that more fuel is required, and otherwise you'd run really lean, and do nasty things to your engine.

[JekylandHyde]

garfer03, yes I was talking about the 3SGTE.

The 3SGTE that 99% of us run has no idea that boost is being added and it does not add fuel based on fuel. As I stated above, the fuel pressure regulator adds 1 psi of pressure for each psi of boost. Unless you have a Gen III engine from Japan that no longer uses the AFM, that is how your car is set up.

The ECU does add fuel based on volumn of air flow, but it has no way to know that that volumn opf air is under pressure.

The OEM MAP sensor only does two things: operate the OEM boost gauge and control fuel cut. The ECU never "sees" what boost level the engine is at.

[MR-355-5sfTe]

so why would someone (like myself) want the 3sgte map sensor for a their NA project? especially since the NA ecu won't recognise its use? will it have ANY effect of fuel cut.... or should that be left to the sacf and a fpr?

[JekylandHyde]

I've never done any "na" projects so I have no idea.

[garfer03]

sorry if i sounded rude J&H, but i had only read the second post and then responded to that, and before i knew it, several people had posted before me while i was typing a response.