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Closed loop boost target


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In the G4+ boost control was locked to MAP, this is becuase generally the aim of boost control is to keep cylinder pressure constant.  You generally tune to a acheive a cylinder pressure that the engine can safely handle.  If you use MGP for boost control then the cylinder pressure will vary with baro, this means anything related to cylinder pressure will vary - engine power, suspectibility to knock, etc.

In G4+ this has been opened up to allow other control strategies such as pre-throttle pressure but its still recommended to use MAP in general.  

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  • 3 months later...

With a closed loop boost target, would it be reasonable to set higher DC at lower RPM to help with spool and torque production?  Something like this:



Or is this not really necessary due to the Stage1 DC %?

Is there any preference for Base DC Mode to be Stage 2 vs Stage 2-3?

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Stage 1 handles the spool.  

Base DC mode generally depends on how much the DC needs to change as RPM increases to keep boost on target.  Since you have a flat 54% across all RPM's above 3500 stage 2 mode would probably work well for you.  If you had say 54% at 3500RPM but 65% at 6000RPM like is more typical then you would want to use stage 2-3 mode so the base DC follows what is in the table.

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  • 3 weeks later...


For this type of overshoot on a 3-4 gearshift, does this seem more like a P or D issue?  Activation issue?

Stage 2 on - 5.5psi

Stage 3 on - 2.2psi

P - 5.0

I - 0

D - 0.8

Base DC is about 29-30%, minus the IAT trim.  From the descriptions it seems like increasing D or decreasing P would have very similar effects.  Some overshoot isn't that big of a deal, since my highest target boost is 20psi, and it's tuned up to 22psi, but if I can even it out a little bit, I'd like to.  In 3rd gear I ramped into the throttle more slowly than the gear change.

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