boost spike ? what causes it and dont bash me please
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This is a discussion on boost spike ? what causes it and dont bash me please within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; boost spike ? what causes it and dont bash me please. I own 07 wrx wagon, with turbo xs turbo ...

  1. #1
    Registered User bullrider's Avatar
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    boost spike ? what causes it and dont bash me please

    boost spike ? what causes it and dont bash me please.

    I own 07 wrx wagon, with turbo xs turbo back ,and cobb access port stage 2 what causes car to serge under load ?
    is that boost spike , or do I have a other problem ?

    if it is boost spike how do I fix thanks for any help
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    Registered User StylzWRX's Avatar
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    On the EJ25, catless turbo back will cause boost spiking as I understand, but that should be resolved with EM I believe, and you mention you have the COBB AP.

    I have an 07 Limited wagon and have not replaced my DP yet for that reason. I am opting for a High Flow DP and catless out from there.

    If it is indeed a boost issue, other than maintaining at least one cat, I don't know what can resolve the issue. Someone else may be able to chime in here cuz I'd like to know too...
    Last edited by StylzWRX; 05-21-2009 at 07:30 PM.
    2007 WRX Limited Wagon in WR Blue
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    Admiral Ackbar the 1st mycologist's Avatar
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    Quote Originally Posted by bullrider View Post
    boost spike ? what causes it and dont bash me please.

    I own 07 wrx wagon, with turbo xs turbo back ,and cobb access port stage 2 what causes car to serge under load ?
    is that boost spike , or do I have a other problem ?

    if it is boost spike how do I fix thanks for any help
    Can you describe the surging any better? Wrxs have a non-linear power band because of the turbo. Normally the power builds abruptly after the lag period, then tapers off slowly.

    You can measure the boost with the accessport - have a friend watch it. Spiking would be shooting over the target initially (a little is normal). If it is wandering up and down that is boost hunting and would feel like the car is stumbling then picking back up. Both could be related to the boost control system.



    Quote Originally Posted by StylzWRX View Post
    On the EJ25, catless turbo back will cause boost spiking as I understand, but that should be resolved with EM I believe, and you mention you have the COBB AP.

    I have an 07 Limited wagon and have not replaced my DP yet for that reason. I am opting for a High Flow DP and catless out from there.

    If it is indeed a boost issue, other than maintaining at least one cat, I don't know what can resolve the issue. Someone else may be able to chime in here cuz I'd like to know too...
    Your thinking of boost creep.
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb
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    Registered User StylzWRX's Avatar
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    Quote Originally Posted by mycologist View Post




    Your thinking of boost creep.
    Would you mind elaborating?
    2007 WRX Limited Wagon in WR Blue
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    Boost surging/hunting is usually caused by a mechanical problem with the wastegate, vacuum line leaking. At least that was what caused mine.
    '02 WRX 4EAT, 311,000KMs/194,500Miles, Sold. Best car I ever had. '09 STi stage 1, hope this one will be good too...
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    Registered User bullrider's Avatar
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    I do have up pipe and high flow cat ,

    the car seems to stumble , or surge in boost sum times
    will a tune fix ( surge = on off power )like it whants to rip ass but cant.
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    Admiral Ackbar the 1st mycologist's Avatar
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    Quote Originally Posted by StylzWRX View Post
    Would you mind elaborating?
    Boost creep is the big deal, we have a sticky on it. It is uncontrollable increase in boost because of wasetgate limitations (mechanical), not fluctuations due to control issues.

    Quote Originally Posted by bullrider View Post
    I do have up pipe and high flow cat ,

    the car seems to stumble , or surge in boost sum times
    will a tune fix ( surge = on off power )like it whants to rip ass but cant.
    What our friend from CN said (wastegate actuator) plus check for a restrictor pill and the bcs in your search.
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb
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    OMG WTF MainFrame's Avatar
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    Quote Originally Posted by WyomingWagon View Post
    If any knowledgable scooby specialissts would like to take e quick peek at this data log from a wide open throttle i am having a hard time diagnosing this boost spike. right at 4700 rpm i jump from 15 to 19.7 psi then right back down.
    no cel or fuel cut. this is a link to the log. thanks https://drive.google.com/file/d/0B0p...it?usp=sharing
    I have UP, TBE, turbo inlet, injectors, intake

    You could create a new thread for this.. include as much information as you can, including what kind of car you have, what modifications are done to it, and the circumstances surrounding when this issue first started. Hard to answer questions when we don't even know what kind of car you're talking about.

    Also, your link doesn't work. It's telling me the file doesn't exist.
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    zax
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    Agreed. New thread please. This one is 5 years old and I would say Dr. John has answered all the questions from the OP. Closed.
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