Exaust Help Please!!!

[KH06]

I just put a turboback Turboxs exaust on my 07 MS3. Other than the normal pain in the ass moments, the install went good. I started to drive it and i noticed as i boosted ( mainly in 4th but sometimes other gears) that their were sudden jolts. I then realized that I went from 16PSI to the range of 20ish. I am guessing that their is not enough fuel and its cutting boost. Some of the things i thought that would cause this are:
-I have an HKS BOV that is VTA. I heard many problems about this but before the exaust everything was fine

OR

- I am also planning on getting a COBB Acessport. Maybe a tune will fix the problem?

Has anyone else had these same jolts? Any advice would be appreciated!

 

[Darth Vader]

So...you're running a VTA blowoff and now a full turbo back exhaust on the stock tune and you're wondering why there's driveability issues? This car CAN NOT run a VTA blowoff right without a tune, period and, especially, now you've loosened up the exhaust side.

Get tuning if you're going to continue to run this combination. That's my opinion on the matter.

 

[H3br3w_Ham3r]

How is it cutting boost if it is getting up to 20 psi? Also are you running catted or cat less? Cat less downpipes lead to boost creep and big spikes. You need a manual boost controller if that's the case.

 

[MSMS3]

Try going to full recirc. I'm running the stock BPV with a good CAI and full TurboXS catless three inch DP/RP into the stock CBE and having no problems. I do get transient boost spikes into the 20-21 psi range right after a WOT upshift, but it immediately settles back down to 16-17. This is normal.

Also, you do need to do a reset on your ECU and give it time to "learn" from the new data it is receiving. 50-100 miles of normal day to day type driving, should do the job.

However, your VTA setup is sending inaccurate MAF sensor data to your ECU. Accurate MAF measurements become more critical when you really open up the exhaust with the big high flow DP.

I say you should consider putting your stock BPV back on at least for a temporary test. Cobb recommends you use the stock one if you go with their AP tune. I believe there is info on their web site about aftermarket BOV's especially running VTA causing or contributing to boost creep when running big DP/RP exhaust or higher than stock boost on our cars.

See if the stock BPV solves your problem and stick with it or set up your BOV for full recirc. Chances are good that with that change and some time for your ECU to "learn" the changes, your problem will be solved.

 

[Captain KRM P5]

Try going to full recirc. I'm running the stock BPV with a good CAI and full TurboXS catless three inch DP/RP into the stock CBE and having no problems. I do get transient boost spikes into the 20-21 psi range right after a WOT upshift, but it immediately settles back down to 16-17. This is normal.

Also, you do need to do a reset on your ECU and give it time to "learn" from the new data it is receiving. 50-100 miles of normal day to day type driving, should do the job.

However, your VTA setup is sending inaccurate MAF sensor data to your ECU. Accurate MAF measurements become more critical when you really open up the exhaust with the big high flow DP.

I say you should consider putting your stock BPV back on at least for a temporary test. Cobb recommends you use the stock one if you go with their AP tune. I believe there is info on their web site about aftermarket BOV's especially running VTA causing or contributing to boost creep when running big DP/RP exhaust or higher than stock boost on our cars.

See if the stock BPV solves your problem and stick with it or set up your BOV for full recirc. Chances are good that with that change and some time for your ECU to "learn" the changes, your problem will be solved.

good advice right here

 

[Saskatchewan17]

good advice right here

Very good advice indeed.

Just stick that stock bypass valve back on and disconnect the battery, then open the doors to bleed the charge in the system. Drive sanley for 100 miles and see if your problem goes away.