Cobb SF Intake Help
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This is a discussion on Cobb SF Intake Help within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; I just bought a slightly used intake from someone on here and installed it yesterday. It sounds amazing! Totally not ...

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    Registered User SoFloRex's Avatar
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    Cobb SF Intake Help

    I just bought a slightly used intake from someone on here and installed it yesterday. It sounds amazing! Totally not what I expected but I like it! A couple questions i have is, the stock air port that you have to take off to install the airbox then put back on before you install the top of the air box is loose. I replaced the two plastic pins that I took out to remove the air duct but back by the air box, it has wiggle room of about an inch vertically. I'm sure this isn't how it's supposed to go so does anyone one have a suggestion?
    Second: I do not have a AP yet. I did the install myself and am positive everything is hooked up correctly. I let the car idle for about 5 min after install, letting the computer know that the engine will be taking on more air. When I took it out for a drive, no matter what gear I am in, at around 4000 rpm, the car hiccups and hesitates then continues on normally. My first assumption was the car isn't used to it completely yet, second logic was that it had to do with me not having an AP. Didn't know if this was happening to anyone else that could help me out???

    I appreciate it in advance!

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    OMG WTF MainFrame's Avatar
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    The ECU can't just "know that the engine is taking in more air".. the problem is that since the MAF tube is changed the sensor may be telling the ECU your car is taking in more or less air than it actually is. The MAF probably needs to be rescaled.

    The map for the intake on the AP should have the MAF properly scaled for it.

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    Registered User kprugbyplaya's Avatar
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    Not sure about the installation, but from my knowledge around here is that when you add an intake, you should always tune it. I am assuming the reason why it is doing that because it is not tuned.

    If you want to get the AP, COBB offers maps for that intake. You could always do OpenSource if you don't have the money.



    My best solution is to be on stage 1 with your car, assuming you don't have anything else done.


    Someone more knowledgeable will reply to this and tell you exactly what is happening and what to do.

    Your MAF scaling seems off
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    Registered User kprugbyplaya's Avatar
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    Yeah, what mainframe said
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    zax
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    Quote Originally Posted by MainFrame View Post
    The ECU can't just "know that the engine is taking in more air".
    This is false

    Quote Originally Posted by MainFrame View Post
    The MAF probably needs to be rescaled.
    This is not
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    OMG WTF MainFrame's Avatar
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    Quote Originally Posted by zax View Post
    This is false


    I meant in open loop with an improperly scaled MAF sensor (since his problem at 4000rpm is obviously in the open loop fueling strategy). Unless they've changed something I don't know about..

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    Oh boy.. Intake and no tune?.. /dead

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    zax
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    Quote Originally Posted by MainFrame View Post
    I meant in open loop with an improperly scaled MAF sensor (since his problem at 4000rpm is obviously in the open loop fueling strategy). Unless they've changed something I don't know about..
    I'm teasing you Robin
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    Quote Originally Posted by zax View Post
    I'm teasing you Robin
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    "Supreme Subaphile Extraordinairre" ninefourteener's Avatar
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    Try cleaning the MAF thoroughly.... and then reset the ECU.

    If it still hiccups at high RPMs.... could be a fuel delivery issue.... check your fuel filter.

    "only" an intake (especially a quality one) shouldn't cause these problems you've described.
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    Quote Originally Posted by ninefourteener View Post
    "only" an intake (especially a quality one) shouldn't cause these problems you've described.
    On 2008+ WRXs, they very well could since the intake was changed. They need to be tuned for on the 3rd Gens.
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    zax
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    Quote Originally Posted by ninefourteener View Post
    "only" an intake (especially a quality one) shouldn't cause these problems you've described.
    Respectfully, I completely disagree. With my Fujita CAI, the stock MAFv scaling was appalling... with differences as high as 15-20% in the mid-range OL fueling. However, the Cobb SF intake (for GD WRXs/STis) were designed to mimic the flow of the stock airbox, so the differences should be much less.
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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by zax
    Respectfully, I completely disagree. With my Fujita CAI, the stock MAFv scaling was appalling... with differences as high as 15-20% in the mid-range OL fueling. However, the Cobb SF intake (for GD WRXs/STis) were designed to mimic the flow of the stock airbox, so the differences should be much less.
    Cobb's MAF scaling for their maps (as per Phatron):


    Remove the intake until you can make the necessary ECU calibrations...
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    zax
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    That graph BETTER be for a 3G WRX... else Cobb has some 'splaining to do...
    2015 CWP WRX STi ... But how did I get roped back into an EJ motor?!
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  16. #15
    Registered User maus's Avatar
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    Go back to stock until you can tune that intake. Do it ASAP.
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