need help - boost problems
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This is a discussion on need help - boost problems within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; My second 2002 WRX. I bought it used. STi v7 shortblock, TurboXS FMIC, Power Enterprise Radiator, TurboXS Dual Stage MBC, ...

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    need help - boost problems

    My second 2002 WRX. I bought it used. STi v7 shortblock, TurboXS FMIC, Power Enterprise Radiator, TurboXS Dual Stage MBC, IHI VF-22, HKS BOV, UTEC.. a bunch of other stuff, but I think that's all that's relevant to this thread.


    When I picked up the car it was misfiring on all four cylinders and basically had no oil in it. The misfire was because of a map that was way too aggressive, I've since fixed that (and added oil).

    Car ran good for the first day. I wanted to see what the boost was set at on the second stage (first stage was hitting 18-19psi in fourth gear). So I went WOT in 4th and flipped the switch on the controller. I felt a little push, but the the car immediately started cutting out. I let off and figured it was hitting boost cut. But then it started cutting out on the first stage of the MBC. I can see the boost gauge jumping whenever it's cutting out. It's almost like air is escaping from the system somewhere.


    I took the car to my guy here at home and we tinkered with it. Compression test, changed plugs, etc. But it's still cutting out with the boost set at anything over 14psi. If I keep it turned down to 14psi you would never know anything's wrong. But obviously with a VF-22 I should be able to push more than just 14psi.


    My tuner here was saying the next thing he wants to try is updating the firmware on the UTEC and retuning it. Which I've been wanting to do anyway, but I don't think this is the problem I'm having with boost since it ran fine when I first got it. All up until I tried the second boost setting..

    I would like to get all the problems sorted out and everything set up how I want it before I have the UTEC flashed.



    I did find a plastic T-joint (pictured below) that was cracked and allowing air to escape. I replaced it hoping that was what's causing my problems, but it didn't change anything.

    I've thought about taking everything apart between the turbo and throttle body, cleaning, then reassemble it all to see if there might be a leak somewhere.


    Also, there appears to be a mount missing on the hot side of the IC tubing where it can attach to the intake manifold (also pictured below). The tubing obviously moves because it has been rubbing on the underside of the hood and I have duct taped it to keep from wearing a hole in the tube. I'm wondering if I could get this mount from TurboXS.

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    Subaru Newb MainFrame's Avatar
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    Forgot to mention, STI Pinks injectors (I guess that's 550cc?). I'm not sure about the fuel pump. It must be upgraded since the car dynoed 295whp before I got it.


    Anyways, if it turns out to be some kind of turbo failure then I guess I'll be in the market for a FP Green and some 800cc injectors.

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    Buying a modded used car I'd be really really interested in getting some datalogs on the car. That would be my first guess that the map is screwed up somehow if there isnt an obvious mechincal issue.

    Also it's possible the BC is bad.
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    Quote Originally Posted by 302@12psi View Post
    Buying a modded used car I'd be really really interested in getting some datalogs on the car. That would be my first guess that the map is screwed up somehow if there isnt an obvious mechincal issue.

    Also it's possible the BC is bad.


    The tuner I had look at it checked out the map I'm using and he said it's fine. I think if it had something to do with the tuning then it would have been a problem from the beginning instead of just popping up after I flipped the BC.


    I had thought about the BC, and when I checked the voltage at the switch it was something like 6.4 volts . After downloading the instillation instructions it's supposed to have 12 volts (duh!). I don't know where it's getting that power from because the wire runs down underneath the car and it's so close to the ground I can't see where it goes.

    I'm thinking about pulling the wire tomorrow and hooking it to the cig lighter wire to see if that does it. I also have the original MBC that came with the UTEC, so I might try hooking that up if the other thing doesn't work.

    I tried unhooking the BC, but then it only hit 10psi, and since the problem doesn't hit till 15psi that didn't help any..

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    Today I tried installing the old boost controller that came with the UTEC. After turning it up three times it still never hit over 9-10psi, just like if there was no boost controller. So I guess that one's no good..


    Then I tried rewiring the dual stage controller. That didn't help either, still cutting out.



    If I remember correctly, it can hit higher boost without cutting out before the engine is warmed up. I don't like doing this tho cause I'm sure it's not good for it.



    What would cause the boost to be jumpy after the car is warmed up, but not before?



    I'm running out of ideas here.. I'm about to just take the car to my tuner guy and tell him to figure it out and get it fixed, then take a cab to avis and rent a car.

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    So right now you cant get above 10psi at all with either BC? I'd be suspect of the wastegate.
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    No, using the dual stage BC I can still adjust the boost. And it's fine up to 14psi, but anything higher than that and it starts cutting out.. I can get it up to 18-19psi, but the higher it goes the more it jumps around and the rougher the car runs.


    I did notice where the two parts of the BC come together it's kind of loose and I can wiggle it back and forth, so I might try putting some silicone around the joint if it ever stops raining outside.
    Last edited by MainFrame; 08-18-2008 at 11:47 AM.

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    Here is the part currently under scrutiny.. it was so dirty (not to mention poorly installed) I figured I would be best off taking it off and cleaning it before I reinstall it properly..

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    Well that did nothing.. I'm fed up, I think I'm gonna call tomorrow and schedule a time to drop the car off and let somebody else try to figure out what's going on with it.

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    Hmm.. I don't really have the money right now to have somebody else work on it. I've been thinking, could hitting too much boost have caused a problem with the wastegate? It kinda feels like when it gets ~14-15psi air starts escaping from the system. I was thinking through the intake charge, maybe a leak in the intercooler tubbing. But if exhaust was popping the wastegate open at WOT it would kinda be the same feeling wouldn't it?

    I've questioned the quality of this VF-22.. from what I've heard, IHIs aren't exactly the highest quality.


    Maybe I need a supplemental spring on my wastegate? I wish I had some tools here, I would pull the turbo off myself and examine it, clean everything, and polish it up.

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    I just seafoamed my engine and I may have found the culprit. As the motor died it blasted a puff of smoke out where the BOV attaches to the IC pipe (pictured below). I don't think air should be able to escape through there.. Bad gasket? Anyone know where I can get this gasket?

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    Get some gasket paper and make your own if the local parts shop cant match it up.
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    Quote Originally Posted by 302@12psi View Post
    Get some gasket paper and make your own if the local parts shop cant match it up.

    Good idea.. thanks for helping me out on this.

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    Wow.. worst looking gasket EVAR!! Half of it is non-existent. I'm surprised the car ran as well as it did. This had better be the problem.

    I got a roll of this rubber gasket stuff from autozone. After I eat dinner I'm gonna cut a new gasket and see if this fixes my problems.

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