to much boost????? HELP!!!

[bandit121]

I recently installed a boost gauge and mbc on my car completely stock with the boost set at stock 9 psi because I didn't have exhaust. Everything was running great with that set-up execpt the boost would spike to about 12 when i was on the throttle hard, but i heard that was somewhat normal with the stock turbo. Today I installed a 3" downpipe on the car without any cat-back section just to see how it would run. I went for a ride and after turning the boost controller all the way down, it still runs at 15 psi when on the throttle all the way. I still believe the turbo on the car is stock and it does have 130k on it. I don't believe that i have any vacuum leak because i double checked everything. I also checked the boost controller by blowing air through it to make sure it's working. I could really use any help.

 

[WhiteTsiAwd]

Reason being is because of the DP. And i believe that it would also have something to do with your wastegate.

 

[oldman]

I recently installed a boost gauge and mbc on my car completely stock with the boost set at stock 9 psi because I didn't have exhaust. Everything was running great with that set-up execpt the boost would spike to about 12 when i was on the throttle hard, but i heard that was somewhat normal with the stock turbo. Today I installed a 3" downpipe on the car without any cat-back section just to see how it would run. I went for a ride and after turning the boost controller all the way down, it still runs at 15 psi when on the throttle all the way. I still believe the turbo on the car is stock and it does have 130k on it. I don't believe that i have any vacuum leak because i double checked everything. I also checked the boost controller by blowing air through it to make sure it's working. I could really use any help.

Does it "SPIKE" or "CREEP" Tto 15psi? Did you do a proper boost leak test or just eyballing it? Always do a boost leak test after you've mess with IC pipes or vacumm hoses.

 

[dot]

If you're running a 3" downpipe with no other exhaust your certainly going to creep. You could probably stop it by putting a cat on there, other wise good luck, you could also port out your wastegate area and 02 housing.

 

[bandit121]

First off I've "heard" that on a turbo car just the turbo would cause enough back-pressure for the exhaust. I figured that since i'm running an open downpipe there's alot of air flow going through the intake making the turbo keep boosting because it thinks there isn't enough boost going through. I dunno if that makes sense right now. Second off i tried hooking up the stock boost control system and it still creeps to over 15psi. Also how would i perform a "proper" leak down test for the vaccuum lines. And where should i port the wastegate? Thanks for your help

 

[oldman]

boost leak

http://www.vfaq.com/mods/ICtester.html

boost creep

http://www.dsmtuners.com/forums/showthread.php?t=153141&highlight=boost+creep

and

http://www.vfaq.com/FAQlocator-porting.html

 

[dot]

First off I've "heard" that on a turbo car just the turbo would cause enough back-pressure for the exhaust. I figured that since i'm running an open downpipe there's alot of air flow going through the intake making the turbo keep boosting because it thinks there isn't enough boost going through. I dunno if that makes sense right now. Second off i tried hooking up the stock boost control system and it still creeps to over 15psi. Also how would i perform a "proper" leak down test for the vaccuum lines. And where should i port the wastegate? Thanks for your help

You're right, our cars really don't need back pressure from the exhaust, they will perform well without, but that doesn't mean you won't get boost creep. The amount of air running through your intake has nothing to do with your boost creep.

Here's how it works: You only have a 3" open downpipe so there's vitrually no back pressure. Your wastegate opens at the desired boost but exhaust gasses will bypass the wastegate because they will flow easier out the normal exhaust. So you should port out the wastegate area of your turbo and your 02 housing so that they might exit or install a cat to create some back pressure.