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      01-07-2015, 01:15 PM   #29
polo 335
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Drives: BMW E92 335D stage 2
Join Date: Feb 2013
Location: Europe

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Quote:
Originally Posted by iaknown View Post
So as some of you know I have been pulling every last hair out trying to solve my overboost issue. I think I finally have a solution.....

So to get everyone up to speed, I am running open exhaust. I thought this was the cause of my overboost but it turns out it wasn't (though it definitely makes it worse). I got a hold of the stock/SCR midpipe for the car and put it on and I was still overboosting. Probably just a psi or 2 but enough to set the "Boost Sensor Range" code while running Jarek's stage 2 tune. Running the stock midpipe just like most of you are told me something else was wrong on the car. With Jarek's help as well as the help of a few of the members on the forum I ruled everything out. Even replaced my boost sensor and wastegate solenoid (pressure converter), still no dice.

So I finally ended up opening up (porting) my wastegate in the car. See before and after below. Had to remove the downpipe and engine mount again to do so but it appears to have come out ok (no holes ). After logging boost with no exhaust (downpipe only) I am right where I should be, so it made the difference I needed.

If you plan to run open exhaust you will probably need to do this to stay in the safe zone. Also, if you are running another tuner besides JR Auto's and you don't get codes with straight exhaust, your warning codes have probably been tuned out, you are still most likely overboosting, and probably slowly hurting your turbos.

It also sounds like another member will be presenting another solution (though a bit more involved) shortly .
Very clever mod Iaknown. I encounter the same overboost issue with my 2007 european car and I will certainly do the same mod. Thanks What diameter is the new wastegate? Is it possible to create an underboost issue if the hole is too large when the wastegate is opening?
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