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Message: <blockquote data-quote="COBB Tuning" data-source="post: 1590858" data-attributes="member: 30143">Ambient conditions will change target boost pressure in a few different ways - through charge air temperature (post intercooler air temp.), intake air temperature (pre turbo air temp.), barometric pressure, and the torque model.  At high charge air temperatures, target load will be decreased which will also decrease your boost pressure target.  Also, when intake air temperatures are very high, an airflow-based limit can decrease target load and boost pressure.  At low barometric pressure, a baro.-based compensation will decrease airflow limits and target load to keep the shaft speed of the turbo in-check, since lower baro. pressure will result in lower compressor inlet pressure.  Without lowering boost targets with significantly lower compressor inlet pressure, the pressure ratio across the compressor will increase significantly along with turbo shaft speed.  All of these limit features are in the factory calibration and are maintained in our OTS calibrations.In cold conditions, charge air temperature based timing compensations will increase ignition timing.  When this happens, the torque model can reduce target boost pressure to make sure that torque and power output remain consistent and safe.  I doubt that ignition timing would be advanced enough in 30-40*F ambient such that the torque model was capping boost pressure to 12 PSI, so I would agree that you most likely have/had a boost leak.Two other things to consider - 1) if you were in 2WD, traction control could have been cutting in and closing the throttle to stop wheel slip.  As you might expect, this will significantly cut down on boost pressure.  2) boost pressure targets are not constant through the rev range.  Our OTS, like many other calibrations, runs a pretty steep taper of boost pressure towards redline.  So if you were only going WOT at higher RPM, you wouldn't see the same peak boost pressure on the Accessport gauge screen min/max values as you would if you did a pull through the entire rev range.If you want any more help diagnosing the issue, feel free to send in a datalog of a 4th gear pull from 2500RPM to redline to <a href="mailto:support@cobbtuning.com">support@cobbtuning.com</a>.  Make sure that you're using the default datalogging list.  We can take a peek and see if we can offer any more specific advice.-Sam@COBB</blockquote>

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