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Thread: Boost Leak? Help!?

  1. #1

    Default Boost Leak? Help!?

    Hey Everyone,

    I drive a 2009 BL MPS 3.

    Since i've serviced my car and had my gearbox replaced for the wong noise (which is back), i've noticed that the car feels slower.

    This is my first turbo car as well as my first manual car.

    My car just use to build boost steadily and power felt progressive.

    Whereas now the boostgauge doesn't quite fill as easily and at lower rpm's (1500 -2000)there isn't even the slightest hint of boost?

    IF i plant my foot it seems to fill alot faster but just feels as though it isn't maintaining boost?

    Is this the normal characteristic of a turbo car?

    Or maybe the infamous 'detuned' feel after a service?

    Any recommendations on how a newb like me can check for a boost leak?

    Will the turbo spool in neutral if i rev it?

    And if i keep the bonnet open is the typical sound a 'hiss' sound?

    Sorry about all the questions but any light on the matter will be appreciated.

  2. #2
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    Hey SP23HO, I dont think many tubo cars would start to build boost at 1500-2000 rpm, because it wouldnt be reving hard enough to make enough exhaust to make the turbo spin. I think most MPSes here start to kick in boost at about 3500-4500 RPM if I am not mistaken. Personally I find it hard to drive mine at 1500-2000 RPM, it gets grumpy at me, so I generally maintain cruise at about 2000.

    When you plant the foot do you hear the engine roar but not go much faster then when you reach about 4000rpm start to pull away hard?

    From my experience, and this is my first turbo car that I have been driving for a year, there is nothing progressive about a turbo. It is either off, or on and on hard.

  3. #3
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    Quote Originally Posted by ZedN View Post
    Hey SP23HO, I dont think many tubo cars would start to build boost at 1500-2000 rpm, because it wouldnt be reving hard enough to make enough exhaust to make the turbo spin. I think most MPSes here start to kick in boost at about 3500-4500 RPM if I am not mistaken. Personally I find it hard to drive mine at 1500-2000 RPM, it gets grumpy at me, so I generally maintain cruise at about 2000.

    When you plant the foot do you hear the engine roar but not go much faster then when you reach about 4000rpm start to pull away hard?

    From my experience, and this is my first turbo car that I have been driving for a year, there is nothing progressive about a turbo. It is either off, or on and on hard.
    sorry ZedN, if you were talking about a WRX/evo, then what you said would be true, as these have "big" turbos on them, so it takes longer to spool, but the MPS has a "small" turbo, so it's making boost by 2500 rpm, with max boost kicking in around 3000rpm, and staying there till ~5000rpm
    if you look at missy's graphs here you can see the stock tune boost in red: http://www.ozmpsclub.com/forum/off-t...tml#post127684
    the hiss sound is pretty typical, it's the air being sucked in by the turbo, it's more obvious if you have a SRI as well

    unfortunately i cant give too much advice on the issues you have SP23HO
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  4. #4
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    Quote Originally Posted by SP23HO View Post
    Hey Everyone,

    I drive a 2009 BL MPS 3.

    Since i've serviced my car and had my gearbox replaced for the wong noise (which is back), i've noticed that the car feels slower.

    This is my first turbo car as well as my first manual car.

    My car just use to build boost steadily and power felt progressive.

    Whereas now the boostgauge doesn't quite fill as easily and at lower rpm's (1500 -2000)there isn't even the slightest hint of boost?

    IF i plant my foot it seems to fill alot faster but just feels as though it isn't maintaining boost?

    Is this the normal characteristic of a turbo car?

    Or maybe the infamous 'detuned' feel after a service?

    Any recommendations on how a newb like me can check for a boost leak?

    Will the turbo spool in neutral if i rev it?

    And if i keep the bonnet open is the typical sound a 'hiss' sound?

    Sorry about all the questions but any light on the matter will be appreciated.
    My bet is they flashed your ECU. I had exactly the same experience when Mazda replaced my water pump under warranty. Never said a word to me about touching the computer, and tried to deny it afterwards. It wasn't till I said that, given what they'd told me I'd like to have them look at the car (under warranty of course) because it was down on power, that they finally "remembered" that the TSB for the ECU update was applied.

  5. #5

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    SARCASTIC is correct; The MPS DISI engine is running boost from around 2500rpm. Mine bites in (delightfully) viciously at this point, such that you need to be aware of intruding on that realm when being a bit heavier-footed and exceeding normal traffic TPS which is around 20% when moving away from slow points. I know that seems low, but still gives adequate performance that doesn't attract attention. Much more than this, and with boost climbing but still well under maximum, I just find that all the traffic I was recently a part of is now well behind me.

    If you are hearing a hiss revving up with no load and the bonnet open, it is most likely induction. A note: please don't do this on a cold turbo! If driving and solidly on boost, a quite different hiss than that made by induction may indicate a boost leak, but it seems unlikely, and a boost guage may indicate boost decay. The ECU re-flash story seems more likely.
    CP_e Standback & PNP; CP_e 3" SS Downpipe; Corksport FMIC with Top-mount K&N filter & OEM Ram CAI; Turbosmart BOV; Dashhawk; Prosport Boost Guage; JBR solid shift bushes; DBA 4000 Wiper-Slot front rotors; Hawk Ferro-Carbon HPS Street front brake pads (@ 69,000km); Sumitomo HTRZIII's in 225/45 x 18

  6. #6

    Default

    I had the same issue where I suspect mazda has detuned my ECU. The car just feels down on torque now. Is it even legal to sell someone a car stating certain power figures and then detune it afterwards?

    I might be wrong but i can get positive manifold pressure just before 2000rpm with full boost before 3000rpm but i try not to go full throttle so early in the rev range

  7. #7
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    Quote Originally Posted by Toddy22587 View Post
    I had the same issue where I suspect mazda has detuned my ECU. The car just feels down on torque now. Is it even legal to sell someone a car stating certain power figures and then detune it afterwards?

    I might be wrong but i can get positive manifold pressure just before 2000rpm with full boost before 3000rpm but i try not to go full throttle so early in the rev range
    The legality has been questioned here before... Not too sure about it myself, but it does make me wonder what else mazda tinkered with while the car was there!

    Luckily its only $2000 to put the car into MRT to get its power back

  8. #8
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    @ "only $2000"

  9. #9

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    Quote Originally Posted by Scaredycrow View Post
    The legality has been questioned here before... Not too sure about it myself, but it does make me wonder what else mazda tinkered with while the car was there!

    Luckily its only $2000 to put the car into MRT to get its power back
    Not so easy when your in WA

  10. #10

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    A good case for Standbacks!

  11. #11
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    Who tuned your standback Dougy?

  12. #12

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    , Thanks for the info everyone!

    Might have to have a talk with my service department in my next service.....

    Feels like a completely different car!

    @ 2K to fix it

    Dyno day on the 30/10 so i wonder if the lack of performance will show up there!

  13. #13

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    SC, Hi. I do my own. I build up what I want in cells in Excel, then smooth them using a contouring package and then copy them into the SB database before uploading. I guess it's not perfect but the car starts, idles and runs well, doesn't spit and fart, pulls like there is no tomorrow and has good fuel economy. I haven't changed the tune in ages now.

    I only have one small bug that irritates me and that I need to fix in due course but I think it is related to an inability of the current FMIC system to depressurize fast enough on lifting off throttle for shifts or when there are turkeys on the road in the way. It didn't do it until I installed the FMIC. Corksport didn't reply to my emails, typical for Yank companies.

    I'll try a second BOV on the turbo outlet side when I have time. My son had the same issue when he put a huge supercharger on his Holden, and beat the problem by using a second BOV.
    CP_e Standback & PNP; CP_e 3" SS Downpipe; Corksport FMIC with Top-mount K&N filter & OEM Ram CAI; Turbosmart BOV; Dashhawk; Prosport Boost Guage; JBR solid shift bushes; DBA 4000 Wiper-Slot front rotors; Hawk Ferro-Carbon HPS Street front brake pads (@ 69,000km); Sumitomo HTRZIII's in 225/45 x 18

  14. #14
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    Quote Originally Posted by Doug_MPS6 View Post
    SC, Hi. I do my own. I build up what I want in cells in Excel, then smooth them using a contouring package and then copy them into the SB database before uploading. I guess it's not perfect but the car starts, idles and runs well, doesn't spit and fart, pulls like there is no tomorrow and has good fuel economy. I haven't changed the tune in ages now.

    I only have one small bug that irritates me and that I need to fix in due course but I think it is related to an inability of the current FMIC system to depressurize fast enough on lifting off throttle for shifts or when there are turkeys on the road in the way. It didn't do it until I installed the FMIC. Corksport didn't reply to my emails, typical for Yank companies.

    I'll try a second BOV on the turbo outlet side when I have time. My son had the same issue when he put a huge supercharger on his Holden, and beat the problem by using a second BOV.
    Very cool. Ironically the very reason i DON"T want a standback. I work in IT and enjoy tuning up database systems etc, reckon I would be too tempted to play with the tune all the time. Knowing me I'd get it running perfectly right before zoom-zoom-boom! A flash is good way to keep me out of my ECU!

    You have a non-stock turbo also yes? The FMIC / BOV is probably engineerd with stock boost volumes / pressures in mind.

  15. #15

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    SC, Nope, turbo is OEM. Never had any work done on it, apart from attaching a DP to it.

  16. #16
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    Quote Originally Posted by Doug_MPS6 View Post
    SC, Nope, turbo is OEM. Never had any work done on it, apart from attaching a DP to it.
    Ahh my bad, thought you were one of the guys with the 2871 internals.

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