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Thread: A poser for the turbo experts...

  1. #41
    Guest itrhondaboy's Avatar
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    just fit a wb02 and afr gauge and figure it out mate then argue with yourself why its blatently overfueling

  2. #42
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    I don't see why there seems to be tension in this thread purely because someone is asking how, or why something acts the way that it does.

    I for one like to know how or why things work and I'm sure that there are many other people that read this thread that might like to know also?

  3. #43
    Guest mantachris's Avatar
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    Quote Originally Posted by dan_t View Post
    I don't see why there seems to be tension in this thread purely because someone is asking how, or why something acts the way that it does.

    I for one like to know how or why things work and I'm sure that there are many other people that read this thread that might like to know also?
    ^^^^^

  4. #44
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    Quote Originally Posted by dan_t View Post
    I don't see why there seems to be tension in this thread purely because someone is asking how, or why something acts the way that it does.

    I for one like to know how or why things work and I'm sure that there are many other people that read this thread that might like to know also?
    good post

  5. #45
    Guest itrhondaboy's Avatar
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    the tension comes from 1. Its been explained 100s of times if you use the search button 2. Its been explained at least 5 times on this thread but still we all keep getting told were basically wrong! Do we need bren, si norris jez has already given his input! Respected [] tuners!

  6. #46
    I <3 BBS LM Actual_Ben_Taylor's Avatar
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    Haven't read the whole thread.

    The main problem you get with a vent to atmosphere dump valve is stumbling when you partially let off the throttle. If you just just snap shut throttle then it isn't very noticable.

    Oh and the same sort of issue when you're accelerating hard and snapping the throttle shut then open quickly on gearchanges.
    Last edited by Actual_Ben_Taylor; 03-01-2010 at 23:04.

  7. #47
    Guest EvilScotsman's Avatar
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    aye for a split second! and even that is down to the fuelling strategy nissan decided to write in the ecu program! That doesnt prove the physics of the problem

  8. #48
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    Quote Originally Posted by itrhondaboy View Post
    the tension comes from 1. Its been explained 100s of times if you use the search button 2. Its been explained at least 5 times on this thread but still we all keep getting told were basically wrong! Do we need bren, si norris jez has already given his input! Respected [] tuners!
    Please show me where it was explained.

  9. #49
    Guest EvilScotsman's Avatar
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    Look. Everyone is still blindly believing this is necessary behaviour, post the maths to prove what you are saying, i have.

    If you cant put up the figures or formulas, then you dont deeply understand the answer you are giving.

  10. #50
    Guest EvilScotsman's Avatar
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    Quote Originally Posted by dan_t View Post
    Please show me where it was explained.
    Me too.

    And you "tuners" and friends can get as annoyed as you like, put up or shut up

  11. #51
    I <3 BBS LM Actual_Ben_Taylor's Avatar
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    Like I said, if you just slam the throttle completely shut immediately then there isn't a problem.

    However that's not what happens when you're driving. Its when the throttle plate is partially open that you get overfueling, like when you're just coming off the throttle after a WOT run

  12. #52
    Banned sideways14a's Avatar
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    Every sr20 on this forum that has a VTA dv will over fuel on change, this is easy to prove as a quick search from the past 10 years will show a rather lot of posts on the subject.

    Its not bullshit, its not fookin myth... It happens... now i dont have any figures or shit, quite honestly i couldnt be bothered to do it as the overwhelming evidence proves it happens.

  13. #53
    Guest EvilScotsman's Avatar
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    the throttle slams shut every gearchange, unless you keep your foot on the pedal?

    Ok I give up, and will go away for now.

    Even im getting fed up with the same blind answers.

    Jesus some of you people are nuts! I only asked an engineering question, and got burned at the stake for witchcraft! The SXOC shows its true colours when a serious question that doesnt involve bodykits comes up...



    Cheers lads
    Last edited by EvilScotsman; 03-01-2010 at 23:16.

  14. #54
    I <3 BBS LM Actual_Ben_Taylor's Avatar
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    Quote Originally Posted by EvilScotsman View Post
    the throttle slams shut every gearchange, unless you keep your foot on the pedal?
    Yeah, and then when you immediately go back to WOT theres no air in the pipes between the turbo and the throttle body as its just been dumped. So it overfuels while the pipes fill back up with air...

  15. #55
    Guest itrhondaboy's Avatar
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    Quote Originally Posted by dan_t View Post
    Please show me where it was explained.
    look through page 1 and 2 mate!
    The dump valve problem comes from the origional programming of the stock ecu it can be mapped out, the fact is once a dumpvalve is fitted the over fueling begins, im not highly technical and cant be arsed searching google for a technical explaination. The ecu is programmed for the recirced air to be there so is fueled accordingly but due to the air being recirced behind the maf the ecu doesnt know its not there on overrun, but still adds the fuel as if it was there! Therefore same fuel amount+incorrect air amount= over fuel

  16. #56
    Guest frisbee's Avatar
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    The engine managment system has been designed to work with the standard recirc valve (it even has a hole in it for some reason). People have had MAF problems when fitting some aftermarket turbos and its been shown to be sensitive to distance from the turbo, bent intake pipes etc.

    Its not a "physics" problem as such, its a secondary sensor and ECU problem.

  17. #57
    Guest EvilScotsman's Avatar
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    doesnt matter anymore, you neophytes have killed the inquisitive nature in me. What you said last mate, everything is physics. Physics is everything.

    I give up, the earth is flat

    Burn me now, you know you want to.

  18. #58
    Guest itrhondaboy's Avatar
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    and were the frig does this '' the throttle slams shut'' crap come from? That would make the engine completely cut out!

  19. #59
    Guest EvilScotsman's Avatar
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    Quote Originally Posted by BenTaylor200 View Post
    Yeah, and then when you immediately go back to WOT theres no air in the pipes between the turbo and the throttle body as its just been dumped. So it overfuels while the pipes fill back up with air...
    Theres a slight DELAY till that space fills up.

    Air moves as a single liquid mass.

  20. #60
    Guest EvilScotsman's Avatar
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    The throttle plate has a tiny hole in it, or a gap under it, called the idle air bypass. Slams shut, means closed to normal tick over setting.

    Like when you take your right foot off the throttle.

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