Inaccurate Gauge or bad BCS?
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This is a discussion on Inaccurate Gauge or bad BCS? within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; For some reason my car isn't making full boost. Car is stock 2004 WRX besides a Perrin catback. I'm only ...

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    Inaccurate Gauge or bad BCS?

    For some reason my car isn't making full boost. Car is stock 2004 WRX besides a Perrin catback. I'm only getting 10psi in any gear at WOT. There are no boost leaks and all vacuum lines have just been replaced and restrictor pill IS in the line at the correct spot. I'm kind of at a loss of what to make of this. I'm not sure if 10psi in any gear would be a symptom of a bad BCS or not? Is there any test that can be done to confirm that my BCS is still working correctly? The only other thing i could think of is that my boost gauge is way off (prosport electrical). Unfortunately i don't have any other way to monitor boost so it's difficult to determine what to do. Any advice or input would be appreciated!

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    Moderator Donkey's Avatar
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    So you installed the gauge and it was 10psi or you installed the gauge and have seen stock boost #'s and now they are lower?Also what gear are you looking at max boost in?These cars are tuned from the factory for 4th-5th gear max boost.Boost is load dependent so you will not see max boost in 1st-3rd gear on stock ECU tuning.1-2nd will be like 8psi.3rd is like 10psi.4-5th is 13psi.
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    I have never been able to see peak boost numbers with the gauge. The highest it's ever gotten is almost to 12. But 9 out of 10 pulls it will only go to 10psi. I always check in 4th and 5th gear but every gear is 10psi even. I'm not sure if the gauge is just way off or if i'm really not making full boost. If a BCS is bad what would you see for boost.......close to 10psi?

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    Master Baiter EJ257's Avatar
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    I couldn't go higher than 9PSI when I had a bad BCS
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    Does it sound possible that it's my BCS then? I pulled the BCS out of the car and unplugged everything. Shouldn't I be able to blow through one hose and feel the air coming out the other hose? It seemed like the air wasn't passing through.

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    Moderator Donkey's Avatar
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    Quote Originally Posted by FCPremixx View Post
    Does it sound possible that it's my BCS then? I pulled the BCS out of the car and unplugged everything. Shouldn't I be able to blow through one hose and feel the air coming out the other hose? It seemed like the air wasn't passing through.
    Thats because it is closed when not energized.Try using some lead wires and the car battery to test it.You should hear it click.Also try cleaning it out with a electroncs safe cleaner.Most autostores sell some.
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    I hooked up my BCS to my battery and it did click everytime it got power. Does this rule out a bad BCS?
    Last edited by FCPremixx; 05-21-2009 at 01:22 PM.

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    Registered User volodyalysak's Avatar
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    I'm getting 0.6 Bar, which is around 8 PSI, checked all hoses, wastegate arm in place. Also tested car in safe mode, and didn't hear BCS to click...
    Is there any way to test BCS for sure ? I mean without buying one.
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    Admiral Ackbar the 1st mycologist's Avatar
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    Sounds like it is stuck. You can blow through the hose when it is energized if it is working correctly.
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    "The stitch is lost unless the thread is knotted." - Italian proverb

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