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loss of boost after shifting

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Old Oct 9, 2011, 08:54 PM
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loss of boost after shifting

so i think it could be my boost controller but im not sure i have a hallman mbc im running 19lbs as of now when i pull in any gear weather its 1st 2nd 3rd or 4th when i shift and put it back to wot it will only hold 14psi like its by passing the mbc any ideas could my mbc be bad?
Old Oct 9, 2011, 09:02 PM
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You may have a small boost leak.

N
Old Oct 9, 2011, 09:04 PM
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would a boost leak anywhere in the system cause that or going to the mbc?
Old Oct 9, 2011, 09:16 PM
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That's close to wastegate pressure so your boost controller might be being inconsistent. Check the simple stuff like EGR hoses though, you might have just blown one off.
Old Oct 9, 2011, 10:17 PM
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Are you still using the factory airbox snorkel?
Old Oct 10, 2011, 09:24 AM
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Might be the boost controller I had the same issue until I changed my boost controller!
Old Oct 10, 2011, 09:26 AM
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check for boost leak... and check wastegate
Old Oct 10, 2011, 09:38 AM
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it may be boost leak or a bad bov
Old Oct 10, 2011, 10:47 AM
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You may also experience this when you get back-pressure in the exhaust. Can happen when your cat is going bad. The material in the cat can breaks up and in extreme circumstances it can clog the exhaust stopping your turbo from spooling. I had the honeycomb of material actually turn sideways in the exhaust, you can imagine the affect it had on the turbo. More than likely though you just have a boost leak.
Old Oct 10, 2011, 11:08 AM
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Sounds like a boost leak, is your gate recirculated?
Old Oct 10, 2011, 11:19 AM
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First do a boost leak test.
Then find a buddy who has a MBC which works and try his.
Old Oct 10, 2011, 01:20 PM
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Originally Posted by EvoJoeIX
Are you still using the factory airbox snorkel?
why would this even matter? factory airbox snorkel just diverts air to the filter. people still use the snorkel for aftermarket intakes. it has nothing to do with boost pressure.

check for boost leaks. check your mbc as well.
Old Oct 10, 2011, 02:12 PM
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Originally Posted by sujinX
why would this even matter? factory airbox snorkel just diverts air to the filter. people still use the snorkel for aftermarket intakes. it has nothing to do with boost pressure.

check for boost leaks. check your mbc as well.
Actually if the factory snorkel is not being held down it will lift up and cut boost. Happened to me and everyone said it was a boost leak. Thank god someone suggested I check mine or I would have never figured it out.
Old Oct 10, 2011, 03:52 PM
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maybe itd help if i did a list of current mods since i just started using the forum anyways as of right now i have a stm intake no maf aem series 1 tail bov unrecirc stm upper intercooler piping buschar racing racing intercooler and lower piping with a fp white rabbit turbo and spooling up cop hallman mbc i think it might be the boost controller going bad to bad no buddy close has one i could hook up
Old Oct 10, 2011, 07:05 PM
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Originally Posted by thedru13
Actually if the factory snorkel is not being held down it will lift up and cut boost. Happened to me and everyone said it was a boost leak. Thank god someone suggested I check mine or I would have never figured it out.
are u kidding me? the snorkel doesnt do shiet to boost. its exactly what its name is. my stupid snorkel flaps all over the place but its not going to affect my boost because its not even connected to anything BUT the radiator support beam. all its doing is moving some air from the front towards the top of the filter if that.
the OP has an stm intake, he prolly doesnt even have a snorkel. if he does its just to divert air to the filter. how is that going to cut boost?
to build boost u need compressed air in a chambered atmosphere. if he's losing boost its somewhere in the charged air section. the only other area is if his intake is completely closed off resulting in no air induction. i dont see a snorkel doing that.

if the snorkel can really "cut boost" then the evo is horribly made. im sorry to say that, i guess i bought the wrong car.


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