i am stumped
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Evolving Member
Joined: Oct 2007
Posts: 114
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From: ashland pa
i am stumped
i cant control my boost.
i really need a tune but i cant make it to redline without overboosting.
i have a mbc hooked up correctly, i even called an evo tuner shop to confirm. i even tried hooking up a different high dollar needle valve thinking the valve i bought was junk. still no luck.
i start with 13 pounds of boost and by 5300 rpms i am at like 22 pounds! i cant afford ecb right now.
does anyone want to take a stab at it? cuz i have my new cams in since thanksgiving, and i never got to go wot throttle yet. and all evo owners know thats no fun.
i really need a tune but i cant make it to redline without overboosting.
i have a mbc hooked up correctly, i even called an evo tuner shop to confirm. i even tried hooking up a different high dollar needle valve thinking the valve i bought was junk. still no luck.
i start with 13 pounds of boost and by 5300 rpms i am at like 22 pounds! i cant afford ecb right now.
does anyone want to take a stab at it? cuz i have my new cams in since thanksgiving, and i never got to go wot throttle yet. and all evo owners know thats no fun.
Evolving Member
Joined: Jul 2005
Posts: 294
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From: Norfolk, VA
Why don't you just stay out of boost until you take the car to get tuned. Otherwise, try to turn the mbc all of the way down. Also, you are driving around with aftermarket cames without a tune...you really need to get tuned before other issues come into play.
you sure its not in backwards?
friend of mine put an mbc on his car and it was spiking like 25+ psi. i took a look at it, and you could hear it sucking in air. flipped it around and worked perfectly
friend of mine put an mbc on his car and it was spiking like 25+ psi. i took a look at it, and you could hear it sucking in air. flipped it around and worked perfectly
Evolving Member
Joined: Jul 2005
Posts: 294
Likes: 0
From: Norfolk, VA
This link has some pretty informative info and pics...maybe check through and make sure you have followed the provided diagram.
One of a few possible scenarios... I have tried a few different boost controllers in the past. One of them would not control boost just as you're stating. Mine shot up to 35 psi at one point!
Best thing to do is find a friend or a shop to help you out real quick and try a known working MBC in your car. Then go from there. Isolate one variable at a time.
Make sure you took the restrictor pills out of the stock boost lines if you reused them
Run a straight vacuum line from your boost source to the wastgate actuator and see what your gauge reads. (should be 11-12 psi.)
Double check that everything is installed correctly, such as the BOV and intake snorkel.
If you have any luck with any of the above, then you know how to fix it. The easy way is to try a different MBC real quick or try the MBC bypass.
Best thing to do is find a friend or a shop to help you out real quick and try a known working MBC in your car. Then go from there. Isolate one variable at a time.
Make sure you took the restrictor pills out of the stock boost lines if you reused them
Run a straight vacuum line from your boost source to the wastgate actuator and see what your gauge reads. (should be 11-12 psi.)
Double check that everything is installed correctly, such as the BOV and intake snorkel.
If you have any luck with any of the above, then you know how to fix it. The easy way is to try a different MBC real quick or try the MBC bypass.
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Thread Starter
Evolving Member
Joined: Oct 2007
Posts: 114
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From: ashland pa
3" turbo back w/ no cat, hks 272 cams , short ram intake, walbro255
where exactly are the resrtictor pills cuz i looked at the diagram and the only line i left on was the short one from the wastegate three inches to the tee
where exactly are the resrtictor pills cuz i looked at the diagram and the only line i left on was the short one from the wastegate three inches to the tee
Sounds like BOOST CREEP. I have the same thing. HAve you tried running wastegate pressure (no MBC or anything) and seeing if it stays constant at spring pressure or if it keeps rising?
If it still rises on spring pressure then you have boost creep. You will either need to introduce more restriction to the turbine outlet (i.e. a cat or something) or you will need to reduce the restriction where the internal WG vents(porting or the like). A regular o2 housing would most likely only exacerbate the issue unless it is ported on the WG side. Hope this helps
If it still rises on spring pressure then you have boost creep. You will either need to introduce more restriction to the turbine outlet (i.e. a cat or something) or you will need to reduce the restriction where the internal WG vents(porting or the like). A regular o2 housing would most likely only exacerbate the issue unless it is ported on the WG side. Hope this helps
Thread Starter
Evolving Member
Joined: Oct 2007
Posts: 114
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From: ashland pa
well it was that little 3 inch line coming off the wastegate. i still dont understand what a damn restrictor pill is. but i still run 20 psi with the controller all the way down like the wastgate just cant get rid of it. lesson learned i guess
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