System_S4k

I have been trying to chase down a lean spike for those that don't know. I decided it seems to happen at peak boost and as the boost tapers off, the car richens up.
The link at the bottom of the page shows a fuel pump test. It clearly shows that a walbro 255hp (like I run) opens a valve and dumps fuel pressure at 85psi. I run a 4bar FPR, which is 58psi. That means at arond 27psi of boost (85psi fuel pressure), my fuel pump should crap out. Sure enough, my lean spike seems to happen when I spike to 27psi. As my boost tapers, the fuel comes back and the car richens up.
This is 1.8bar or 27psi. Right at 85psi fuel pressure.
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This is 1.6 bar or 24psi. 82 psi fuel pressure, or just under the 85psi limit.
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At 1.5bar or 22psi. 80psi fuel pressure, or 5 psi under the limit.
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Here the ECUx logs laid over each other. Blue line has a 27psi boost spike right where the car goes lean. The rest are at under 85psi fuel pressure. No lean spike.
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The load on all of these runs is past 191, so I don't think this is a software problem. It seems clear to me that the Walbro 255hp does indeed crap out at 85psi. At this point, the only thing left to do is try a different pump. There is apparently a Bosch 044 HP that can handle the fuel pressure I need.

ar design

The bosch 044 is a definite hit.

LaserAvantS4

my 6 months old 044 starts to whine prety loud after a long drive. is it sign of it dying?

ar design

I will ask my fuel pump guy on Monday if you want.

audidweeb

Josh's(Docwyte) is pretty load too. I think they are all that way.

LaserAvantS4

thx!

DocWyte

Mine makes a ton of noise all the time. Still works fine tho, think they're all like this.

System_S4k

The 044 is a LOUD pump. I have an external one on the DSM and it is louder than the engine....

LaserAvantS4

thanks. i'm relieved

ar design

If you are really concerned, keep an eye on the WB02 if you have one.....