Boost Drop - What could be the cause?

[rs-mad]

Hi,

Just looking for some ideas that you guys may have as to why my boost curve has dropped off as opposed to holding boost as it normally does?

The image attached shows what the boost curve should be and what is it.

I have a feeling it is a boost leak and will be looking at the fuel trims later today but just want to know if anyone has seen anything like this before I go looking

Thanks in advance.

RS-MAD

[S2tuner]

I don't think it's a leak, as the boost you're holding at redline is identical to the "normal" curve.

[rs-mad]

S2Tuner - Thanks for replying.

What you say does make sense as the requested boost for both curves is pretty much the same.

But boost has dropped off at 3500rpm as opposed to holding until ~5000rpm.

RS-MAD

[flashyg]

Boost controllers get tired. try changing usually clears up this mid drop issue.

[rs-mad]

You mean the N75 valve?

RS-MAD

[rs-mad]

Just went a and logged:

MB032 (Stored and Idle Values)
MB033 (Idle values)

RS-MAD

[Nige_RS4]

When you say normal and not normal, do you mean requested and actual or are you comparing a boost log from a different day? If from a different day, then there could be any number of factors that could change your boost curve slightly. There doesn't seem to be any units of measurement on the vertical axis?

[rs-mad]

Nige - The boost decrease has been more than what would normally occur on a day to day.

See new curve

Normal = What boost should be
Not Normal = What boost is and shouldnt be

RS-MAD

[rs-mad]

Problem diagnosed

RS-MAD

[Blue_Thunder]

What was the issue?

And i'm still unclear what you meant by your 'Normal' boost curve. As Nige asked, was this what you've previously logged as your actual boost on the car, or was this the specified boost?