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  1. #1
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    question about boost

    ok - amk s3 - when accelerating, should i get full boost from the minute i put the foot down, or should it go to around 7psi and then gradully increase as the revs go up?

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  3. #2
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    depends what rev range you are in mostly, but you will never see full boost at the moment you put your foot through the floor because a turbo works on exhaust gases and needs a short time to spool. At around 4k upwards if you put your foot down you should have pretty instantaneous boost.

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  4. #3
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    Quote Originally Posted by future View Post
    depends what rev range you are in mostly, but you will never see full boost at the moment you put your foot through the floor because a turbo works on exhaust gases and needs a short time to spool. At around 4k upwards if you put your foot down you should have pretty instantaneous boost.

    tom
    Expect peak boost at around 4000 RPM.
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  5. #4
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    yeah i get that part - what i'm trying to find out though is - does everyone else with a standard s3 boost at around 7psi straight away and then gradually increase as the revs go up.

    in othewords, what revs do you have to be at before you get the full 21psi?

  6. #5
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    Quote Originally Posted by m8arx View Post
    yeah i get that part - what i'm trying to find out though is - does everyone else with a standard s3 boost at around 7psi straight away and then gradually increase as the revs go up.

    in othewords, what revs do you have to be at before you get the full 21psi?
    A standard S3 won't boost to 21 PSI? You would expect that from a mapped S3, but not a standard one... ?
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  7. #6
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    Quote Originally Posted by Welly View Post
    Expect peak boost at around 4000 RPM.
    ok so basically i should see 21 psi at 4k, and not 7 like i am, which then gradually increases?

  8. #7
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    what shoud it boost too then? 17-18psi?

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    Quote Originally Posted by m8arx View Post
    what shoud it boost too then? 17-18psi?
    Stock? Should be like 0.8 bar on a 210 S3, a little more on a 225. That's like 11-12 PSI.

    It sounds to me like, if you are getting boost rising all the way through the revs, that something is wrong. What you have there is basically boost creep.

    I'd check that your actuator pipe isn't split for starters, that there isn't a split in any of the N75 hosing. Failing that, I would start looking at the N75 valve and the actuator.

    I'm shocked that it hasn't come up with a fault code for max charge pressure exceeded.

    It's standard yes?
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  10. #9
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    My freak-of-nature stage one:



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  11. #10
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    Quote Originally Posted by JS1500 View Post
    My freak-of-nature stage one:



    Eeek!
    AT least that is mapped, this one is standard with the boost creeping to 21 PSI.
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  12. #11
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  13. #12
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    Quote Originally Posted by Welly View Post
    Stock? Should be like 0.8 bar on a 210 S3, a little more on a 225. That's like 11-12 PSI.

    It sounds to me like, if you are getting boost rising all the way through the revs, that something is wrong. What you have there is basically boost creep.

    I'd check that your actuator pipe isn't split for starters, that there isn't a split in any of the N75 hosing. Failing that, I would start looking at the N75 valve and the actuator.

    I'm shocked that it hasn't come up with a fault code for max charge pressure exceeded.

    It's standard yes?
    ok sorry, just to clarify, it's 0.7-0.8 BAR and not 7psi.

    there seems to be 2 issue's then. 1st one is the max charge pressure exceeded. i posted about this the other day and have since bought 1animal1's n75, fitted it today. I can't scan it as i don't have vagcom.

    ther problem i replaced this for is there is a bit of hesitation/boost cut at low speeds that i thought this might have cured.

    as for the 2nd issue - the boost guage shows as the revs go up the boost can increase to around 1.3BAR, which is about 18-19psi? this is obviously noyt right

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  14. #13
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    and yes i've checked the actuator pipe and all the pipe's surrounding that area and they're all fine. i have also replaced the TIP and the diverter valve for a forge 007p number last thursday

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    Quote Originally Posted by JS1500 View Post
    My freak-of-nature stage one:



    Eeek!
    Eeek indeed dude, mines mapped and is 19 psi

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    ok so whats the possible explanations for my boost shooting right up towards the top of the rev range, and any suggestions as to why i'm getting what can only be described as a small "boost cut" too, when i'm not gunning it.

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    IId be leaning towards the actuator myself, especially if you've already changed the n75 and checked for leaking pipes in that area.

    Could also be penny valve issue inside the turbo, but I doubt that to be fair.
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  18. #17
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    the turbo's only recently been refurbed less ythen 2k ago. and like **** am i paying to get the turbo taken off AGAIN to have the actuator checked.

  19. #18
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    the penny was missing when the turbo got taken off the first time and there was absolutely no boost whatsoever, but there's definatelyuboost now, but it's just confusing why it's doing this.

  20. #19
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    any other suggestions ????

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    Quote Originally Posted by m8arx View Post
    ok sorry, just to clarify, it's 0.7-0.8 BAR and not 7psi.

    there seems to be 2 issue's then. 1st one is the max charge pressure exceeded. i posted about this the other day and have since bought 1animal1's n75, fitted it today. I can't scan it as i don't have vagcom.

    ther problem i replaced this for is there is a bit of hesitation/boost cut at low speeds that i thought this might have cured.

    as for the 2nd issue - the boost guage shows as the revs go up the boost can increase to around 1.3BAR, which is about 18-19psi? this is obviously noyt right

    i frickin hate cars
    maybe boost leak ? i remeber a wile ago mine used to hesite and sometimes cut out found a tiny split in 1 of the boost pipes .. but you would notice fuel ecconomy to go down ..
    other than that best best is vag-com !!

  22. #21
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    right i've ordered Vag-com this morning and it should arrive tomorrow. which blocks should i be logging, and is it relatively straight forward to set the logging up?

  23. #22
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    What does the gauge read at idle. Vacuum disappears instantly. What gauge do you have I take it that shows vacuum first? Then boost. Not just straight pressure.

 

 

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