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Discussion Starter · #1 ·
i've got an interesting problem... im running a mbc and a bov, i've got an autometer boost gauge. in first and second gears, the boost levels stay solid until about 10 psi then the pressure bleeds out to about 5 psi. but in 3rd 4th and 5th gears the pressure is solid at 15 psi till i let off the throttle. i tried replacing all the 6mm and 4mm hosing, yet the problem remains!! i'm thinking it's my cheap 30 buck ebay bov leaking pressure before i release the throttle, but any advice is helpful! and also... what are normal boost levels during hard acceleration in 1st and 2nd?
 

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Standard boost levels:

Gears 1-2 0.54 bar
Gears 3-5 0.72 bar

Base boost 0.40 +/- 0.03 bar
Pressure switch cut-off 1.15 bar

1 bar = 14.7 psi, you do the math.

When you install a MBC, you should be getting the same boost in all gears, it bypasses the operation of the solenoid valve.
By the sound of it, your MBC is not doing what it should, the ECU is still controlling boost through the solenoid valve.
you may want to check the plumbing, and/or set up the MBC properly.
 

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forgot where I read it, this spec is really for the NG900 automatics but I guess not far off the mark...

0.54 bar in all gears.
 

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Discussion Starter · #8 ·
while checking the tubing for the turbo... i discovered a large tear in the rubber host before the mass air flow sensor that some fool had taped back together with electrical tape. while running, air gushed out from benieth the tape. i cut the host beyond the tear and reattached and clamped it. boost levels stay more constant now and spool up time has greatly improved. its almost like driving a different car now! thanks for all the help
 
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