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      03-07-2009, 02:13 AM   #86
usc335
First Lieutenant
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Drives: '08 E92 335
Join Date: May 2008
Location: so cal

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Quote:
Originally Posted by runningman View Post
The lines look pretty squiggly, even on map 0. Is that a tuning problem or a measuring problem? Also that 16psi boost spike seems pretty scary. What did you do to cause that? Is it something that will be fixed in future maps?
I do believe that the 16 psi spike on the datalog (remember that's in the intercooler charge pipe) is from a throttle closure because my boost gauge only read a little over 15 psi peak hold. From reading the gauge real time and comparing it to datalogs, I think the difference between my gauge and the datlog is normally about 0.5 psi. So, the "extra" 0.5 psi is probably from a minor throttle closure event. At least, that's my guess...
As far as the pressure oscillation goes, remember that the air is moving across the sensor and the pressure will naturally vary due to the pressure waves, boundary layer, turbulence, and flow separation -- so it will never be a constant static pressure. You can also see the oscillation in the stock datalog.