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Boost isn't very smooth, occational overboost

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Hey guys, I'm trying to figure out an issue in my TT. Boost delivery isn't as smooth as it used to be. Under constant throttle application (lets say half throttle) boost will hold at .4bar for a number of seconds when it should really be building up, and then all of a sudden it jumps up to 1.2bar and takes off. Occationally it will jump up to 1.5 bar and hold until I let off (I don't hold it for long, and I try to avoid this). I've got an EPL K16 flash set for 1.2 bar, so 1.5 is overboosting. And then, sometimes I just can't get up to the 1.2 bar...it will max out at .8-.9 occationally.

So far I checked the hoses at the N75 valve, they look ok. I found a big crack in the Y-hose, that plugs into the bottom of the DV's. I replaced that hose, and still have unsmooth boost delivery. What else might be the culprit here? Maybe the N75 valve is on its way out? Sticky wastegate actuators? I haven't gone underneath to investigate them. Any help is appreciated.



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There are several things that can cause weird boost profiles, including those you already mentioned. I may also be related to your re flash software as well. I'm afraid there probably is not a quick answer for this one, it is going to take some diagnostics time to check out all the components one at a time to see where the problems lies.

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As I posted elsewhere, my guess would be a leak somewhere in your system. Do a pressure check. It could be DVs themselves or waste gates. I doubt it's the flash, but the flash does mean you are putting more stress on the system perhaps.

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