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2G Still surging especially when warmed up

Posted by Michael Gomes, Feb 7, 2020

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  1. Michael Gomes

    Michael Gomes Probationary Member

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    Joined Dec 28, 2018
    Riverbank, California
    I'm hoping someone can help me out here I've been having this issue for quite a while I have a 1999 eclipse GST and especially when it warms up when I try to accelerate quickly it will surge I've changed the plug wires they were old and there was a crack in one that you could see the inside. So I got some new wires the plugs are in good shape they are NGK iridium it has stock injectors it has a brand new fuel pressure regulator new stock fuel pump well when I say new I believe my mechanic got it off another car but it was in good shape the only mods I've done are the do-it-yourself ones like the boost control solenoid restrictor removed the blow off valve dump tube cut but it's got brand new Royal purple 5 w 30 oil with wix XP filter it's got new gear oil for the transmission it's a 5-speed it's got a new catalytic converter it runs great except when I get on the throttle it will surge. I'm planning on replacing the coils and possibly the ignition module any ideas guys I love this car and when it's running good its something special and I'm sure I don't need to tell you guys that any help would be appreciated thanks.
     
  2. motomattx

    motomattx Proven Member

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    808
    Joined Dec 9, 2010
    wampum, Pennsylvania
    If you still have a mass air sensor and you removed the bov return pipe to vent it to make sweet noises, then it won't run right, hook it back up and report back.
     

    Drag Race Build 3K  24

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  3. Michael Gomes

    Michael Gomes Probationary Member

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    Joined Dec 28, 2018
    Riverbank, California
    I never removed that tube. I know that venting to atmosphere will mess with stuff. Thanks for the reply though
     
  4. m_0ney_pit

    m_0ney_pit Proven Member

    611
    37
    Joined Jan 12, 2007
    Reading, Pennsylvania
    Try taking a video ? Surging can mean a lot of things
     

    Street Build 2K  0

    1999
    manual · 2G DSM

    Street Build 2K  0

    1999 Mitsubishi Eclipse GST
    manual · 2G DSM
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  5. motomattx

    motomattx Proven Member

    2,158
    808
    Joined Dec 9, 2010
    wampum, Pennsylvania
    Then what is blow off valve dump tube cut?
     

    Drag Race Build 3K  24

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  6. Michael Gomes

    Michael Gomes Probationary Member

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    Joined Dec 28, 2018
    Riverbank, California
    The tube inside the air intake hose connected to the air box and turbo. The plastic hose inside.
     
  7. Michael Gomes

    Michael Gomes Probationary Member

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    Joined Dec 28, 2018
    Riverbank, California
    I'll try to take a video. But when I try to accelerate briskly it's like power is choked off then on off then on
     
  8. Vegas smith

    Vegas smith Proven Member

    2,925
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    Joined Dec 2, 2002
    Houston, Texas
    Hmm, that's difficult to diagnose. Are there any check engine lights coming when this happens?
     

    Street Build 3K  10

    1993 Eagle Talon TSi AWD
    awd · manual · 1G DSM
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  9. ishnish

    ishnish Proven Member

    781
    116
    Joined Jun 26, 2011
    Modesto, California
    Does your car surge on a cold start at idle? Or only when warmed up?
     

    Street Build 1K  9

    1999 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
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  10. Michael Gomes

    Michael Gomes Probationary Member

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    Joined Dec 28, 2018
    Riverbank, California
    No check engine light at all.
     
  11. Michael Gomes

    Michael Gomes Probationary Member

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    Joined Dec 28, 2018
    Riverbank, California
    No idle surging at all. It's only surging under throttle. And pretty much only when I've been driving for a little while. I haven't done a real boost leak test yet. I did a smoke test and it looked like near the blow off valve is where I saw a little bit coming out. Until I can get another BOV I siliconed around where I believed the smoke was coming out from. I also should mention that I did take out the throttle body and check it out and it was really dirty so I cleaned it out completely I cleaned out the idle air control valve and all surrounding areas I even took out the throttle plate and throttle shaft so I could check the seals and they definitely need to be replaced one of them was blown like 3/4 of it was there the other one was completely intact but it look like maybe it was shrunk I'm not sure I'm thinking that could be my issue any thoughts?
     
  12. ishnish

    ishnish Proven Member

    781
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    Joined Jun 26, 2011
    Modesto, California
    Being that you took the throttle plate apart, I think that this could 90% chance be your issue. When I first rebuilt my car from cylinder head and up (bolts ons), I had horrible surge at idle on cold starts and once that was resolved, found out I had horrible idle only after long drives when my engine was all warmed up. Not saying this is only due to the throttle body but majority of the time it is due to the sensors correlated with the throttle body or the seals and O-rings. First thing first is fix the seals. A lot of people who take apart the throttle body and put it back together, don't realize how much they can eff sh*t up just from installing the throttle plate and shaft wrong.

    I had a friend who claimed he rebuilt throttle bodies no problem. I gave it to him and still had horrible surge issues. Then I sent it to Steve Monroe from Throttlebodys.com who explained even the slightest unevenness from the throttle plate and the gaps around can cause issues with idle.

    Here's a pic of my stock 2g tb that had no issues:
    20180117_175758.jpg

    Vs my 1g NT TB that my friend rebuilt that had horrible issues:
    20180117_175818.jpg

    You wouldn't think much of it (at least I didn't), but this was specifically pointed out to me by Steve.
    I highly recommend him too btw. His services are amazing and his feedback and willingness to answer questions even better!

    Here's a post where I explained a little bit of my experience:
    https://www.dsmtuners.com/threads/need-help-car-is-idling-at-over-2000.516753/page-3#post-153685376
     

    Street Build 1K  9

    1999 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
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  13. Michael Gomes

    Michael Gomes Probationary Member

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    Joined Dec 28, 2018
    Riverbank, California
    like I said before my problem is not with the idle it is surging when I am accelerating driving the car the idle is perfect the idle is perfect and I know that I put the throttle body plate and shaft back in correctly I'm positive this I'm pretty mechanically inclined so I know the risks involved and not putting stuff back together correctly it does have bad shaft seals like I said so I know that could be an issue also I had this problem before I clean the throttle body and once again I do not have a problem with the idle the idle is perfect the problem is surging under acceleration
     
  14. Blinkyblinx9

    Blinkyblinx9 Probationary Member

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    Joined Jan 22, 2019
    Clinton, Iowa
    By "accelerating quickly" what are we talking about exactly? Does it only do it at wide open throttle? When you get into boost? Does it at part throttle while keeping it out of boost? You'll have to guess by ear and poke around for a diagnosis if you don't have a boost and wideband gauge and some way to pool data from your ECU. Typically "surging" while "accelerating quickly" sounds like a boost leak causing you to hit fuel cut. That little T25 looses momentum quickly to I can see how it cutting over and over would feel like repeated surging. I would start with a boost leak test.
     

    182  1

    1995 Eagle Talon TSi
    fwd · automatic · 2G DSM
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    1990TSIAWDTALON likes this.
  15. motomattx

    motomattx Proven Member

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    Joined Dec 9, 2010
    wampum, Pennsylvania
    Start with the basics, fuel pressure test, compression test, leak down test, boot leak test. Is this a misfire that your calling a surge or is it an actual surge?
     

    Drag Race Build 3K  24

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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    1990TSIAWDTALON likes this.
  16. Michael Gomes

    Michael Gomes Probationary Member

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    Riverbank, California
    okay thanks for the info yeah I'm going to do a compression test boost leak test and a fuel pressure test get that out of the way to see where my numbers are and go from there thanks for the advice
     
  17. Michael Gomes

    Michael Gomes Probationary Member

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    Joined Dec 28, 2018
    Riverbank, California
    Okay I'll get on that as soon as I get paid I'll keep you guys informed thanks for all the help
     
  18. jcastello214

    jcastello214 Proven Member

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    Joined Jul 17, 2012
    Daly City, California
    Just wanted to add a few cents to this. First and very first thing that needs to happen is a boost leak test. If you are leaking boost and your accelerating it will fall on its face. It may not show as a vacuum leak as the boost pressure may cause the leak. For example when your cooling system doesn’t hold pressure past 5psi and only leaks when hot. Same idea.

    The other thing about throttle bodies is the plate needs to go back in the same orientation that it came out, not backwards or flipped around as it won’t shut properly. Always mark everything you take off the throttle body properly.

    Check your values with a scanner, even a coolant temp sensor can throw off things and not cause a check engine light. Bluetooth Scanners are cheap. After those things didn’t resolve it I would spend the time on other basic diagnostics. It’s always good to do periodically anyways to keep track of your cars condition but I think a lot of people post because they forget where to start.

    I hope that helps a little and you get it figured out!
     

    Street Build 667  0

    1994 Eagle Talon TSi AWD
    automatic · 1G DSM
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  19. DSM90AWD

    DSM90AWD DSM Wiseman

    2,641
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    Joined Dec 22, 2002
    Bear, Delaware
    Other than the boost leak test a few other checks: make sure TPS sensor plug is connected (said you took the TB off), also the Coolant Temp Sensor on the Thermostat housing. ECU will lean out AFRs once engine reaches normal operating temp.. if sensor is bad/not hooked up.. car will run poorly once warm.

    Also I tried Iridium Plugs once and they did not do well for me (turbo cars run rich). Have run NGKs BR7ES and never missed a beat. They also cost $10/set so cheep test if all else pans out.
     

    817  0

    1990 Eagle Talon TSi AWD
    11.899 @ 122.410 · 1G DSM
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