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Josh Smith

Subaru wrx v8 boost problem

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Hi Guys

I am in the process of tuning my vehicle. I have the fuel map done for on boost up to 1 bar up to 7500rpm but as soon as i up the boost to like 1.2bar and it hits 6000rpm it drops to 0.7 bar. I have check the trim tables and monitored and data logged WG Duty cycle  and it is still commanding what i have set. its not hitting any limits.  has any one come across this issue.

Thanks 

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Its not really the boost dropping at 6000, but you have a really odd oscillation below 6000.  

To me it looks more mechanical like the BOV is bouncing open and closed or something.  

If you turn aux 6 off (or unplug boost sol), does the boost curve look more stable?

Jvcmdej.png

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If I drop the wg dc down to 20 it is fine. and when at 24 the boost comes in and out like what you have shown. I have attached another capture of what i mean i would have had the boost solenoid at eith 15 or 30hz when it did this.  i will try another bov tomorrow but don't think that is the problem. this wasn't a problem until link was fitted. Its worth mentioning I have just fitted bolt on upgrades hence why link has been fitted.  Turbo upgrade  GDC Garrett 3071R twin scroll turbo direct bolt on,  ID1050 injectors, dw300 fuel pump, link g4+ hks 3" turbo back exhaust. 

Capture.JPG

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The boost control was set up pretty weird in that map you attached but your log said open loop so I assume you changed to closed loop after the log?  it didnt appear to be doing anything weird anyway, but I would stick to open loop with the same value through the whole WG table until you get it sorted.  25Hz is normally best for a common mac valve. 

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yes running open loop and have tried at 25hz and 20 across the whole table. my process was started at 1 bar boost and go up from there so ie as in increased from 20  to say 21 or 22 duty cycle across the whole table that is when the boost would come up and hold to 6000rpm then drop to .7 bar its like the boost solenoid can't control it  i did a pwm test on the BS and its ok at low pressure but when the pressure increases in stops. can these reach a certain boost level and fail?? 

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21 minutes ago, Josh Smith said:

i did a pwm test on the BS and its ok at low pressure but when the pressure increases in stops. can these reach a certain boost level and fail?

Assuming you have a mac valve?  The mac valves were originally for industrial compressed air pneumatics so should work fine up to a couple of hundred psi.  I would suspect either it is just failing or if it is new it is potentially a fake.  

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Ok, that is a big unknown.  I have never seen anyone use one so have no idea how they respond or if they are usable.

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