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Old 05-16-2019, 01:22 AM   #1
Atomic Wrx
Scooby Newbie
Member#: 492722
Join Date: Oct 2018
2018 WRX

Default Does a new Fuel pump need a tune

Background i have a 2018 wrx,
So just last week i installed full TGV Deletes and egr deletes and a new dw300c fuel pump. Everything looks fine car doesn't seem to starve and fuel pressure builds to above 2k. I have the car tuned for tgv and egr deletes so everything is working fine.
My only question is that ive been looking at my fuel pump duty % and there off instead of being a 100% at start up there 88 and instead of idling at 33% it dose at 77%. Is this due to the fact the car need to be tuned for it or the fact that the pump isn't getting enough amps to fully open the system.
Thanks for any help
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Old 05-16-2019, 11:01 AM   #2
Scooby Specialist
Member#: 76586
Join Date: Dec 2004
Chapter/Region: RMIC
Location: Denver, CO
2006 9-2x Aero


The short answer is- 'No a slightly larger fuel pump should not require a change to the ECU". I'd guess your tuner simply changed the target DC% based on their experience and they would have made this change even with the OEM fuel pump.

The FA20 comes with a fuel pressure sensor and has a 'Target Fuel Pressure', but someone else will have to chime in about how free the ECU is to adjust fuel pump DC% to reach the target pressure.

If there was a problem and the fuel pump was working at 77% just to build enough pressure at idle, then I think it would it would run out of flow well before getting to full boost+higher rpm.

You could watch fuel pressure and see if it drops at higher rpm+boost.

Last edited by vica153; 05-16-2019 at 11:08 AM.
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Old 06-12-2019, 09:24 AM   #3
Scooby Newbie
Member#: 503156
Join Date: Jun 2019
Chapter/Region: NESIC
2016 Sti
Dark Grey Metallic


It seems like everything needs a tune with these cars lol
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