So I finally fixed the exhaust leak on the TII last saturday. Last night, my friend and I were out driving and he wanted to drive. We get onthe freeway and he floors it. I'm watching the boost gauge... 0.6 bar...which is a little higher than before the exhaust leak but no big deal. He backs off and cruises at 55-60 mph for a awhile. Then I tell him to get back on it. He goes from 5th to 3rd at about 55 mph and nails it. I watch in horror as the boost gauge swings up to 0.9 - 1.0 bar!!! That's like spiking from 8.8psi straight to 14.7!!! He lets off and we cruise for a while. He comes to a stop and we take off hard again, just because I'm now curious. 1st...2nd...3rd...hlding steady at 0.6 bar. We get up to 55-60 mph and he downshifts again....needle swings up to 1.0 bar again!



What could be causing this? I'm thinking that maybe the car always had a slight exhaust leak before the turbo (since I've owned it) and that now with the new gaskets it can realize greater boost....but why only when I downshift like that?



Any Ideas?

 

That's actually called "boost creep".

In the lower gears the engine winds fast enough to stay ahead of the turbo.

At high loads in higher gears the turbo gets really going so the waste gate has to let it off.

The stock waste gate is not quite up to the full exhaust flow.



Porting the waste gate will regain control of boost.

 

Ya it tells you how to do it here

WG porting

 

Thanks fo the info, yo.



I'm gonna go ahead and replace all the now uber hard rubber vac lines with larger silicone lines and ziptie the **** out of em.