Underboost problem

[Merdan]

Hi,

2011 A4 2.0Q Revo St2 95ron

I sent my VCDS logs to Revo man and he revealed underboost at higher RMP (screen-shots are here http://www.drive2.ru/l/5318750/) Main mods: CTS testpipe and TDI FMIC
No errors in VCDS, no whistles or cracks under the hood. What can cause the underboost?
Thanks in advance.

[van462]

The underboost code P0299 doesn't trigger unless a certain threshold is met. From what other have posted its around 5psi or 344 hpa low actual boost vs requested. Assuming there are no boost hose leaks the two leading causes are a diverter valve failing and wastegate actuator problems. Here is a link to a post I wrote on the wastegate actuator. http://www.audizine.com/forum/showthread.php/549484-DIY-Diagnose-and-Repair-of-Loose-Wastegate-Flapper-(P0299)?highlight=p0299

[Merdan]

The underboost code P0299 doesn't trigger unless a certain threshold is met. From what other have posted its around 5psi or 344 hpa low actual boost vs requested. Assuming there are no boost hose leaks the two leading causes are a diverter valve failing and wastegate actuator problems. Here is a link to a post I wrote on the wastegate actuator. http://www.audizine.com/forum/showthread.php/549484-DIY-Diagnose-and-Repair-of-Loose-Wastegate-Flapper-(P0299)?highlight=p0299 Thanks buddy, have u seen my logs posted above?