boost problems, half vacuum of normal but occasional overboost
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This is a discussion on boost problems, half vacuum of normal but occasional overboost within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; for starters i have a 2006 wrx with a catless TBE. stock up pipe, silicone intercooler hoses, stage 2 tune ...

  1. #1
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    boost problems, half vacuum of normal but occasional overboost

    for starters i have a 2006 wrx with a catless TBE. stock up pipe, silicone intercooler hoses, stage 2 tune AP, stock TD04L turbo. these are all the mods that im aware of on the car. for starters the car will only ever have a vacuum pressure of anywhere between -11.5 and -8.00 at idle. while driving the car will never reach peak boost and will almost hesistate at times of WOT. my car burns oil like crazy, almost a qt a week, but im replacing my turbo with a TD05H in hopes that it is just a bad turbo seal. recently i did some work on the car where i had to disconnect the battery. on my test drive after reconnecting the battery my car hit almost 19lbs of boost! and then another time i was driving up a hill and it was holding 14lbs! only ever done that once tho.

    im going in to a local tuner on thursday to have my car tuned for the TD05H turbo and im going to have him preform a boost leak check while im in there. no im not just a kid that baught a subi and am having a mechanic do all the wrenching, i know my fair share about vehicles, however im new to the subaru and turboed life. any help or advice on the problem is much appreciated!

    my thoughts on the problem are:
    bad turbo(old turbo had no shaft play)
    boost/vacuum leaks
    bad boost sylenoyd

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  3. #2
    Moderator Donkey's Avatar
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    I guarantee there is nothing wrong with your turbo. Also were you using the Accessport to read the vacuum? Because it doesn't read in inHg. It reads in PSI. I would try datalogging the car to see if that will help pinpoint the problem.
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    I will try that, do you not think the bad turbo seal would could cause me to burn oil? Just a thought. Either way I kinda wanted a slightly bigger turbo and I got it for a good deal. I'll data log once I get everything back to running and post it up

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    Moderator Donkey's Avatar
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    Quote Originally Posted by williamsdouglas View Post
    I will try that, do you not think the bad turbo seal would could cause me to burn oil?
    I can but I would have verified that first instead of just throwing parts at the car hoping to fix the problem.
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    Ok thanks, and isn't it mmHg not InHg? Just wan to get everything right. And also isn't vaccuum not able to be measured in a negative PSI? As far as I understood it everything negative was read in mmHg for vacuum ?

  7. #6
    Moderator Donkey's Avatar
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    And also isn't vaccuum not able to be measured in a negative PSI?
    So if you are using -psi then how do you figure you are only getting "half vacuum"? Generally when people make this statement they have confused -psi with inHg as the manual quotes 18-20 inHg as the norm for vacuum. So if you covert 11.5 -psi to inHg what do you get?
    As far as I understood it everything negative was read in mmHg for vacuum ?
    Vacuum,like positive pressure,can be measure in many different units. You just need to know what units you are using before even referencing the numbers/data.

    Last edited by Donkey; 07-15-2014 at 04:58 AM.
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    Ok thank you for your help, I did some more research h and it seems I just have a small vacuum leak because it is reason in psi. Thanks for your help!

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