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2G Idle increase after FP intake, FP exhaust manifold

Posted by Sjd6795, Mar 13, 2020

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  1. Sjd6795

    Sjd6795 Proven Member

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    Since my idle increased after installing these I'm almost certain this was the reason LOL. Fully warmed up my idle is around 1500, prior to install my idle was probably around 800. Could this also be due to my blown turbo though? I'm thinking about leaving the FP exhaust manifold on but changing the FP intake back to stock.
     

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    1997 Mitsubishi Eclipse GSX
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    Sjd6795

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  2. ThunderChild

    ThunderChild Supporting VIP

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    Sounds like a major boost/vacuum leak to me. I'd double check for any boost leaks.
     

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  3. Sjd6795

    Sjd6795 Proven Member

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    No leaks, my vacuum actual got better after the install. I would only get around -15 vacuum now I get -20
     

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    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
    Sjd6795

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  4. motomattx

    motomattx Proven Member

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    I'm guessing a throttle cable thats too tight or a gasket leak on the intake somewhere, what did you do about your egr valve? did you plug it?
     

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    1995 Mitsubishi Eclipse GST
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  5. Sjd6795

    Sjd6795 Proven Member

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    Intake manifold is stock. The intake I'm talking about is the turbo intake pipe. Throttle cables havent been touched. Only thing was intake pipe and exhaust manifold and the idle changed.
     

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    awd · manual · 2G DSM
    Sjd6795

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  6. motomattx

    motomattx Proven Member

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    Ahh, ok. well then I'm not entirely sure what is going on.
     

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    1995 Mitsubishi Eclipse GST
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  7. randman2011

    randman2011 Proven Member

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    More air is getting into the engine than should. It's as simple as that.

    Are AFR and fuel trim still reasonable at idle? If yes, you have air leaking past the throttle body. You can try adjusting the idle set screw to see if that has any impact but short of a stuck throttle cable or dead ISC valve, that means it's time for a TB rebuild. If trims are adding fuel because it's running lean, you have a vacuum leak after the throttle body. Checking vacuum at idle isn't an appropriate way to diagnose leaks. If you have a boost leak tester, use it. If not, there are other ways but building and using a BLT is both easier and cheaper. And cleaner and safer.
     
    Last edited: Mar 14, 2020

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  8. Fejery4491

    Fejery4491 Proven Member

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    Boost leak test. That's your first step.....
     
  9. Sjd6795

    Sjd6795 Proven Member

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    Placed my stock intake back on the car and started the car to let it idle just to see if I notice anything. I could hear a little air noise near the throttle body so I started feeling around with my finger and noticed the air noise stopped when I put my finger over the gap between this black thingy and the throttle body.

    I have some black silicone coming that's rated for engine gasket up to 500 degrees, would this be ok to use to seal around the leak?
     

    Attached Files:

    Street Build 493  11

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
    Sjd6795

    Street Build 1K  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
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  10. randman2011

    randman2011 Proven Member

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    No. That's the throttle position sensor and needs to stay adjustable. There is a small seal underneath it that you need to replace. I understand that it's one more thing that no one wants to do, but parts are like $10 and it takes 30 minutes to do. One seal on either side of the valve shaft and some rubber gaskets for ISV and FIAV. It's also the perfect opportunity to disable the FIAV if you have ever had problems with that.

    The TPS sensor is not sealed internally, so using RTV to seal it to the throttle body won't solve your problem. It will just make things messy.
     

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    1998 Mitsubishi Eclipse GSX
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  11. Sjd6795

    Sjd6795 Proven Member

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    Can't find the TPS seal for the life of me.. I'm only finding throttle body gaskets when searching. Also how do I go about deleting the FIAV? As far as I know I don't have any issues with it but if I can prevent one why not.
     

    Street Build 493  11

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
    Sjd6795

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    1991 Eagle Talon TSi AWD
    manual · 1G DSM
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  12. Sjd6795

    Sjd6795 Proven Member

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    Found and purchased the shaft seals as well as new inner and outer throttle body gaskets! Hopefully all my parts will be here the same day and I can rebuild my turbo and throttle body!
     

    Street Build 493  11

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
    Sjd6795

    Street Build 1K  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
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    ThunderChild likes this.
  13. ThunderChild

    ThunderChild Supporting VIP

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    Glad you found the leak and are fixing it appropriately. Also if you want a very nice TB rebuild kit, @snowborder714 has great kits, I've used 2 of them and they're excellent quality.
     

    Street Build 733  3

    1990 Plymouth Laser N/T
    fwd · manual · 1G DSM

    711  8

    1987 Toyota Pickup/Hilux
    awd · manual · Misc Vehicles

    Street Build 1K  7

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM

    2K  0

    1992 Eagle Talon TSi AWD
    manual · 1G DSM

    Street Build 3K  10

    1992 Eagle Talon TSi AWD
    awd · manual · 1G DSM
    Loading...
  14. randman2011

    randman2011 Proven Member

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    Joined Feb 26, 2012
    Indianapolis, Indiana
    There is no TPS seal, only the shaft seal that you already found. If you aren't deleting the FIAV or ISC then you don't necessarily need to get the gaskets for those if they're not leaking. I had to do it because I was swapping valves, but it's up to you.

    This post describes how to disable the FIAV without disassembling the TB or buying a blockoff plate. There isn't any benefit to doing this unless you're having idle surge issues but on the other hand I've never experienced or heard of anyone south of Canada having any problems once doing this, so if you want to you could do it as a preventative. https://www.dsmtuners.com/threads/free-fiav-block.391977/

    If you're not familiar, the FIAV is designed to be open when the engine is cold to raise the idle even higher until coolant temp is enough to expand a spring and close the valve. Over time the spring gets weak and doesn't close all the way, hence idle surge. With it disabled or blocked off, the engine gets less air on cold starts. Could be a problem if it's particularly cold but it's not an issue for most of us.
     
    Last edited: Mar 15, 2020

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    1998 Mitsubishi Eclipse GSX
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