So just throwing it out there.
I ordered a fuel pump just in case.

I don't have too much experience with this fuel system.
I'm assuming that base fuel pressure in this car is around 45psi and uses a 1-1 rising rate regulator. (just a guess. I really don't know)

So when installing a 255lph fuel pump, what effect if any will this have?
Will the stock fuel pressure regulator still be able to maintain 45psi base or will the base pressure go up?

If base pressure goes up, how are people compensating? MAF scaling? Other means?

 

Most maps I have seen that "compensate" for the pump are leaning it out a little 5K+ where you'd really start to notice all the extra flow that a stock pump would start to lose. I dont have it in front of me, but something on the order of .6-1.0 points leaner and only in the load cells that you'd taper into (of course, right?).

 

Don't use this as protocol, but this is what was done for a basic 04 ROM (your IX is more advanced and wil pull less fuel for pump )

Red - fuel pump
Blue - intake
Green - Methanol

The rest is just smoothing interprolations and scaling

 

what the hell? Is the bottom left for your upgraded shift knob?

 

Very interesting. I'm curious of the logic behind that....why a fuel pump would affect that specific area and not so much of any other. I would think it would affect hhigher RPM AFR's everywhere.

The map pictured is an open loop map.
So are what people saying is that a fuel pump won't affect idle AFR's and fuel pressure?

 

Correct. Fuel pumps are just like turbos you get flow taper the higher pressure you go, but at an idle the return system isnt overun and bypasses what you dont need back (since its operating at base pressure).

 

I am a beginner but AFR is smooth, and car hauls *** and doesn't knock - thats what important to me

Probably a lot faster than this arrogant person's (below) car who that happens to be the all knowing evo mastermind - the expert in tuning on **** gas on -5 degrees of timing

JK,

Shift knob is stock though

 

Don't ask me, the alcohol changes much of the open loop map

Perhaps razorlab should recommend something on topic besides a direct critisism on other peoples applications. Perhaps he has no advice

Closed loop I think the FPR is open and the excess flows back to tank

 

Interesting. I think it may have to do with the low/high voltage operation of the fuel pump in this car.

In my IS300, if I run dual pumps my base fuel pressure will be 10-15psi higher than if I run a single pump with most FPR's.

 

I tested my regulator yesterday. It was 43.5 PSI that it vented at like it should. After modifying it with a hammer is was about 52.2 PSI. This gives me about 10% increase in fuel flow as I was running out of injector. I simply changed the injector scaling to suit that in combination with my in-tank methanol. Works fine across the range, fuel trims in check, no surprises.

For a fuel pump swap, I would simply confirm that the fuel trims are still sensible, and just retrim the high load fuel areas as per a fresh run on a wideband. If you were on the bleeding edge on your previous fuel pump you'll probably end up leaning it at higher fuel flow areas as your pressure may have been dropping. I can't see there being much effect at all until high revs/full boost unless your previous pump was really struggling.

There is a little solenoid which disconnects the inlet manifold pressure from the regulator during cold start/vacuum conditions. This increases fuel pressure which helps with atomisation of the fuel.

 

Ouch, one joke and I get fried...

but really, mods that change open loop fueling do not just change some load and RPM areas, if you have to you would make overall changes to the map at higher loads where more fuel is needed. The way you sectioned out your map made it look like you believe your intake and FP only changed some loads.

Also, when is the last time you hit load 180-280, 500rpm to 1500rpm?

 

You should see the fuel map that I started with - 13.1's, 12.3's and whatnot floating around in a sea of 10's - I guess that was the tune I purchaced for the fuel pump 2 years ago. It was what I started with nonetheless

Even though I'm not allowed to show the numeric values, a screenshot of just the colors would display enough to describe what the hell am I going to do with this

 

If the regulator never uses vacume to assist opening and only boost via FPR soleniod, I wonder if you could get about 4 psi more holding force at the top of the reg diaghram if you use turbo outlet as the working pressure.

Anyhow, back to the topic of fuel pump tuning and my soon to be famous fuel map , as far as tuning for methyl inj my WOT A:F starts at 11.6 transition, then 10.8 at peak (unavoidable so far), climbs back up to 11.3 and tapers to 11.1 redline.

I'm not sure if a walbro fuel pump will change that much at closed loop due to the sensor-MFI communication, but like he said - check fueltrim_high

 

It isn't always, just cold start otherwise this would be an option

 

Yes, if the EVO didn't have the HIGH/LOW voltage switch to the pump it would suffer the same overrun issues the DSM's have. Without a good AFPR most DSM's with a bigger pump don't drop any pressure when the vacuum line is attached to the FPR, which causes them to run rather rich at idle.

Yes, that will give you 9.5% more flow, to be exact. But, be careful as to how much total pressure you are asking of the pump. At 24 lbs of boost, for example, the fuelpump will need to push 76.2 psi, and most pumps fall off DRAMATICALLY in flow above 70 psi.