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Old 05-10-2012, 05:21 PM   #8
the suicidal eggroll
Scooby Guru
Member#: 51961
Join Date: Jan 2004
Chapter/Region: RMIC
Location: Broomfield, CO
2005 STi
2012 WRX


Originally Posted by Black94Snake View Post
Consider for a moment, the way your stock FPR works. when increasing boost pressure, you also raise your fuel pressure.

Originally Posted by Black94Snake View Post
This in turn increases the flow rate of your injectors, and can cause a rich condition.

The higher fuel pressure is used to offset the higher manifold pressure, so the pressure delta from rail to manifold (the thing that controls fuel flow rate) stays the same at ~43 psi.

Higher boost does mean higher rail pressure, but that does not mean you swing rich. The entire point of the FPR is to keep the rail-manifold delta the same, so your fuel flow rate DOESN'T change with changing manifold pressure.

The OP's problem could have been caused by many things...if the injectors hadn't been tuned for then that's #1 on the radar. If the injectors had been tuned for then like alex said, it was probably a leak or bad MAF scaling.
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