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Possible boost leak

Discussion in 'A3/S3 Forum (8L Chassis)' started by Plunky, Nov 20, 2009.

  1. Plunky
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    Plunky Member

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    [Nov 20, 2009]
    I fitted my fmic yesterday, however the quality of the silicone couplings and clips is quite bad, better ones are on order.
    I have noticed on my boost gauge that the car only peaks at about 14-15 psi, where before it peaked at around 18psi, would this be the cause of a boost leak somewhere in the system? car feels a lot smoother to drive though, even though there is a lack in boost.

    Cheers

    Liam
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  3. ianysm
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    ianysm Active Member

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    [Nov 20, 2009]
    Sounds like it.

    Try going around all the connections and tightening them up then re-check the boost, or wait for your new ones to arrive

    Keen to see if the whole thing makes a difference. I'd love to fit an FMIC
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  4. Plunky
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    Plunky Member

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    [Nov 20, 2009]
    i'll probably just wait, will only be until next week and i dont really need to use the car much.
    I think mine has made a difference in the sense the car is a lot smoother to drive, plus i just love the look of them, dont know why everyone wants to hide theirs!! ha ha
    does anybody know if garages have a machine to check for boost leaks?
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  5. rossbrownlee
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    rossbrownlee Ross_S4

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    [Nov 20, 2009]
    Nah you don't need a machine mate!

    Just find a deserted road, lie on the bonnet slam panel with a bottle of watery washing up liquid squirted on the joints, and get a mate to boot it in third!!

    Sure you'll see the bubbles....

    :moa:
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  6. Plunky
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    Plunky Member

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    [Nov 20, 2009]
    ha ha, thats 1 way of doing it! i'd rather get a mate to sit on the slam panel though! lol
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  7. Prawn
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    Prawn My other car is a MINI!!!!

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    [Nov 20, 2009]
    intersting Liam, I wouldnt have said the turbo in your car is even capable of running 18psi at all. we once ran it by mistake with an MBC where the bolt fell out, so it was running unlimited boost, and still wouldn't boost above 16psi..... and that's the most we could get it to boost with the MBC too.

    also, due to the increased volume of the fmic, and cooler air entering the inlet mani, it'll be more dense, the the hot air pumped by the turbo will occupy a smaller volume when cooled, thus reducing pressure seen in the inlet
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  8. Plunky
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    [Nov 21, 2009]
    yeah when i first got the car it peaked at about 15psi ish, i then got the downpipe/decat fitted, car seemed to boost slightly higher, then i fitted the TIP and it was peaking at around 18psi. This is only the reading from my boost gauge, so i cant be certain this is 100% accurate.
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  9. Plunky
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    Plunky Member

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    [Nov 21, 2009]

    in saying this Nick, do you mean that the peak boost will be lower?
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  10. Prawn
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    Prawn My other car is a MINI!!!!

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    [Nov 21, 2009]
    at the inlet end, yes. the N75 takes it's feed from the same place as before, but the boost gauge takes it's feed from the inlet mani, the the turbo is doing the same work, and sending the same feed to the N75, so nothing changes at that end, but the air comming out of the cooler is more dense, so occupies a smaller volume, so the pressure is a bit lower.

    The airflow going into the engine is exactly the same, it's just cooler, so better for power :)

    edit:| I also didn't realise you'd fitted a downpipe and TIP already, must be going pretty well now mate!
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  11. Plunky
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    Plunky Member

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    [Nov 21, 2009]
    yeah its starting to come along nicely now, just got to sort a few niggily bits out then i can think about the turbo. really undecided at the minute as to weather i shouold just go with a k03s and remap, or go the whole hog and get a hybrid
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  12. ianysm
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    ianysm Active Member

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    [Nov 21, 2009]
    What Prawn said makes alot of sense. Does that mean the boost can now be safely increased abit, hence stage 2?
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  13. Plunky
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    Plunky Member

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    [Nov 21, 2009]
    to be honest i dont know, sounds that way though.
    does anyone know, roughly what sort or % of psi i should loose due to the fmic?
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  14. Prawn
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    Prawn My other car is a MINI!!!!

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    [Nov 21, 2009]
    dude, I wouldn't worry. most people see a few PSI drop across an FMIC, it's perfectly normal.
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  15. s3_kev
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    s3_kev Stage2'd!!!!!!

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    [Nov 21, 2009]
    i never lost any, i gained arond 5psi untill the car re-adapted lol
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