finalzero

Hi,

Was wondering if I read right that the PPP upgarde comes with the Walbro pump (so there would be no need to upgrade it)?

Thanks,

Fz

D1CCY

High capacity fuel pump is only supplied on the 03STi onwards kits (ie blobeye). Rumour has it that this is a Walbro 255 with the markings ground off and a thick rubber sleeve to reduce noise.

Had my 03STi PPP'd over 3 years ago and at a recent remap at SC it was discovered that the stealer had left an original pump in (as he claimed that Subaru UK had supplied the wrong pump) and charged me £178 for the new one. If you're having a remap don't rely on thinking you have the right pump, it must be checked.

finalzero

Its an 05 STi but I am gonna be safe than sorry, doesn't hurt having a higher capacity pump fitted, at least saves one upgrade part in the future when I decide to go for more power.

joey_turbo

iTrader: (26)

Thats what I thought. But I read on here, that it can cause overfuelling. I don't see how, as you are not adjusting the fuel pressure, just putting in a more efficient pump.

brens.scoob

iTrader: (1)

it should have a sticker in the boot at the side of the removable plate saying that an uprated fuel pump is fitted from factory.

-JUST-POOTLING-ALONG-

I am new to this but ,a fuel injector has a selanoid(?) on it that opens , so if the pressure is fine (or higher) it can not over fuel because the lamda sensor differentiates(?) the exhaust gases to control this to the correct setting .Surely this also allows us to fit larger injectors with out a remap or other breathing mods?
If I wrong it is because I am still learning but this surely the best way for a ecu to run?

T5NYW

iTrader: (4)

Not quite true the 02 Sti didn't come with a feul Pump but was retro fitted about 3 months after and supplied from then on all PPP kits. not certain if they replace Pumps on 05STi onwards PPP.

IIRC the ECU opens the soleniod for a "X"mi/sec will give a certain dose of fuel and as long as the fuel presure is within correct pressure band. if it is too high a pressure more fuel (rich) too Low pressure and less fuel (lean). obviously lean is big problem.

IMHO

-JUST-POOTLING-ALONG-

So mixture is set by fuel reaching combustion and has no upset, how dense the air is , so fuel through the injector is the desiding factor . So "x"(Seconds) is not set by the sensor on the exhaust manifold?

T5NYW

iTrader: (4)

Your correct The ECU Map will determine what "X" milliseconds will be, the X m/sec calculated for that ocassion should be the perfect AFR. unless of course fuel pressure drops and the ECU does not know that and cannot recalculate the AFR because of the drop in fuel pressure.

Depending on engine temp sensors are open loop and some are closed loop and what part exhaust sensor, LAMBDA will play in AFR in normal running IIRC.

The "topic" was about Fuel pumps and not how the ECU determins the Air Fuel Ratio. I was trying to extplain pressure drops and effects on AFR by a underated fuel Pump and leaning out will FUBAR your engine.

IMHO