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fuel cut on 12psi on EVO 3 16G?

Posted by RichL19, Jul 16, 2005

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  1. RichL19

    RichL19 Proven Member

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    Joined Jan 23, 2005
    Cawston,
    i just finished intsalling an EVO 3 16G turbo and my SBR FMIC. Im only runing 11-12psi and i swear im hitting fuel cut im on the stock fuel system. When i punch it in firts it pulls like a mother up to 7 grand but then in second it like hits a wall all of a sudden at like 5000 rpm and im only seeing like 11.5psi. Is it fuel cut I diden't think it was possible at such low boost but i don't know.
     

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  2. george5366

    george5366 Proven Member

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    you sure its not a boost leak? might wanna check for leaks before anything
     
  3. RichL19

    RichL19 Proven Member

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    Joined Jan 23, 2005
    Cawston,
    my Psi doesn't drop off could i still have a leak?
     
  4. RichL19

    RichL19 Proven Member

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    Joined Jan 23, 2005
    Cawston,
    to decribe the problem it seems i get full boost around 3800 rpm then it pulls to about 5000rpm then it just like stops hard all of a suuden and back fires then it gets going again.
     
  5. beat90tsi

    beat90tsi Proven Member

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    pittsburgh, Pennsylvania
    full boost by 3800 rpm???
    WTF man?

    how many psi is "full boost" and what gear are you in when you get "full boost?"

    These are important details. You will get the same amount of boost at a higher point in a lower gear. Your spool will not be the same in 5th and first.


    If you are pulling 12psi on an evo3 in 3rd gear or higher, by 3800rpm, then you have some problem. It is possibly boost leak, or bad compression, or an exhaust leak before the turbo, maybe a faulty WG actuator or a number of other things.
     
  6. RichL19

    RichL19 Proven Member

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    Joined Jan 23, 2005
    Cawston,
    yes it seems like a have more lag than i should it cant be bad compression the engine was just rebuilt. I get full boost in first by 3800 rpm in third it is around 3000 but it only pulls untill like 5000 then i hit a wall and back fire.
     
  7. RichL19

    RichL19 Proven Member

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    Joined Jan 23, 2005
    Cawston,
    does 12 psi by 3000rpm in 3rd seem normal.
     
  8. CanadianTSi

    CanadianTSi DSM Wiseman

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    Kingston, ON, Canada
    You have a boost leak.

    My old Evo 3 16g would get 20psi right around 3200.
     

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  9. steve

    steve DSM Wiseman

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    Boulder, Colorado
    A boost gauge while driving can't tell you much about boost leaks except for huge ones. The turbo will just work harder to reach the same boost levels and the ECU will see a lot more air than is really being used and give you fuel for it. That may be the lag you notice due to the turbo having to overcome the leak.

    Steve
     

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  10. RichL19

    RichL19 Proven Member

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    Cawston,
    thank you for your help everybody thank you steve espicially for explaning that to me. I have read many of your previous posts and your knowledge of cars is incredibley impresive. I am very sure i have a boost leak now because at idle im sure i can hear air coming of somwhere on the intake manifold i think it is the injector ports im will do a boost leak tst tommorow and post results.
     
  11. Nicholas Gironda

    Nicholas Gironda Proven Member

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    Joined May 9, 2017
    Spring Hill, Florida
    Did you ever get this taken care if because I am having a similar issue only I’m hitting fuel cut almost as soon as I go into boost on my 1997 Eclipse gst with Evo3 big16g running 550cc,255 walbro rewire
     

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  12. ThunderChild

    ThunderChild Previously tametalon92

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    Thread necromancy!

    Realistically you probably need to get a tuning solution, do you have a way to tune for your mods already?

    The days of tossing to together "close" components and it working without tuning are pretty well done and over. You can check for boost leaks, verify timing (mechanical and base), verify fuel pressure, pump voltage, make sure all the basic maintenance is done etc etc...
     

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  13. brian9397gsx

    brian9397gsx Proven Member

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    Most of the time it's a boost leak. The ecu doesn't care about boost pressure it looks at what the maf airflow. If your getting fuel cut or more accurately spark cut at 11 to 12 psi it's more likely that there is a leak after the maf. What are you using to compensate for the 550s?
     
    brian9397gsx

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  14. Boomdeeze

    Boomdeeze Proven Member

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    Spark cut?
     
    Last edited: Dec 19, 2018

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  15. brian9397gsx

    brian9397gsx Proven Member

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    It doesn't cut fuel when you hit fuel cut it cuts spark.
     
    brian9397gsx

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    1993 Mitsubishi Eclipse GSX
    19.80 @ 35.55 · 1G DSM
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  16. Nicholas Gironda

    Nicholas Gironda Proven Member

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    Joined May 9, 2017
    Spring Hill, Florida
    Ran a boost leak test and bottom injector seals were leaking as was the jpipe. But yes I sent the ecu to be converted to eprom and will have it back soon to run ecmlink. Right now there is a SAFC and I’m installing my innovative wideband before I put it back on the road. Another weird thing is a hissing sound I hear but have no bubbles coming from is the throttle body. Yes literally can hear the air but when I spray the soapy water there are no bubbles or air leaking. It’s a 3000gt throttle body btw. No leaks from throttle body gasket or biss screw. Also redid the intercooler piping since I’ve been waiting for the ecu and slapped a FMIC on
     

    Street Build 128  6

    1997 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM

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    1999 Mitsubishi Eclipse GST
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  17. ec17pse

    ec17pse Freelancer

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    I actually get this myself but its because i have a hybrid 16g and not got my injectors in yet, it happens in high revs in 3rd mainly, the turbo flows too much and it cannot give it enough fuel, its not always a boost leak issue but the turbo just flows too much for the fuel system to compensate,

    Either lower the boost or dont do alot of WOT pulls, i have mine set to 12psi but if you went down to 10psi you might be safe
     

    Road Race Build 7K  34

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  18. Nicholas Gironda

    Nicholas Gironda Proven Member

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    Joined May 9, 2017
    Spring Hill, Florida
    Yeah like I said I did end up having a really bad boost leak at the bottom injector seal but turns out I was missing the 1 of the three rubber booties that go along with the seals on the injectors.

    Had bottom seals and o rings on top but no rubber below the o ring on ither injector. That’ll def do it!!!
     
    Last edited by a moderator: Jan 6, 2019

    Street Build 128  6

    1997 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM

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    1999 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  19. Allen2g

    Allen2g Proven Member

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    Winnipeg, MB, Canada
    Hello, sorry to add onto your thread, I am a new member & im really not too sure how to post my own thread LOL.
    I am wanting to upgrade my T25 to a 16g, the guy i am buying from says i would need to replace the 11psi WG actuator on the turbo to a 7psi one? Is that true?
    He says the 11psi actuator will put the car into boost cut.
    *planning to run the 16g on stock boost pressure which is around 11-12 psi?
     
  20. Vegas smith

    Vegas smith Proven Member

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    That would probably be your TB shaft seals. They need replacing.
     

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