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Low Idle issues

Posted by z_tune, Jan 10, 2012

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  1. z_tune

    z_tune Probationary Member

    26
    0
    Joined Nov 3, 2011
    Fort Collins, Colorado
    Hey guys I need some help diagnosing an annoying problem I've been having. I'll just list every little symptom I have.
    So here's whats happening:
    -The car will always idle around 500 rpm and seems to get worse as it warms up.
    -Idle dips to 200 maybe even to 100 when I shift into reverse then comes back up to 500 ish.
    -surges occasionally maybe 100-200 rpm.
    -almost stalls itself either while slowing down or at a stop (rarely happens but has happened)
    -car seems very stinky and the exhaust tip is very black
    -Loud ticking sometimes from engine, I always thought lifter tick but could be exhaust leak.
    -at 3k rpm cruising the car the rpms will go down then back up but only when cruising at those rpm.

    What I do know:
    -battery, plugs, wires have been replaced
    -small leak where cat connects to catback.
    -no CEL
    -runs fine ironically

    let me know what you guys think might be going on. Currently it sits in my driveway but will be back on the road in a month so I want it running perfect LOL
     
  2. drzdude

    drzdude Proven Member

    35
    0
    Joined Jan 23, 2011
    Huntsville, Alabama
    Sounds like your idle speed controller is not functioning or dirty.
     

    204  0

    1992 Eagle Talon TSi AWD
    · 1G DSM
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  3. pos4g63

    pos4g63 Proven Member

    157
    2
    Joined Sep 9, 2011
    St.louis, Missouri
    Do you have the stock BOV, and is the BOV recirculated?
     

    358  0

    1990 Mitsubishi Eclipse GST
    · 1G DSM
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  4. iugrad92turbo

    iugrad92turbo Proven Member

    10,445
    378
    Joined May 22, 2007
    Kalamazoo, Michigan

    6K  4

    1992 Eagle Talon TSi
    awd · manual · 1G DSM
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  5. z_tune

    z_tune Probationary Member

    26
    0
    Joined Nov 3, 2011
    Fort Collins, Colorado
    I have a rs bov and it is recirculated
     
  6. wraithGSX

    wraithGSX Proven Member

    30
    0
    Joined Jan 9, 2012
    Spring Hell, Florida
    There is a screw in the throttle body,it is on the side of it,facing you near the top.It's like at an angle,and it's recessed,so you have to look for it.Try pulling it out and changing the O ring on it,then put it back,and adjust your idle with it.
    That O ring gets dried out,and it creates a vacuum leak,and some annoying idle problems.
     
  7. jorgea

    jorgea Probationary Member

    1
    0
    Joined Jun 29, 2011
    burbank, California
    I would advice you to have your idle speed controller checked for defects.
     
  8. dsmlover07

    dsmlover07 Proven Member

    173
    1
    Joined Jan 13, 2012
    Kalamazoo, Michigan
    Seven bolt im assuming you can test the isc, tps, adjust the biss screw lots of things in the post above on dsm idle.
     
  9. Tiki2777

    Tiki2777 Proven Member

    914
    61
    Joined Oct 9, 2011
    Omaha, Nebraska
    You could have a boost leak. Mine ran like sh^* and i didn't believe it and when i finally checked the lower intercooler pipes they were hardly connected. I would check you lower intercooler pipes and jpipe if you have one.
     

    Street Build 2K  1

    1998 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM

    Street Build 2K  1

    1995 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM

    868  0

    1998 Mitsubishi Eclipse GSX
    manual · 2G DSM
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  10. dsmlover07

    dsmlover07 Proven Member

    173
    1
    Joined Jan 13, 2012
    Kalamazoo, Michigan
    Ok how about a video, loud ticking? A video would really help.
     
  11. z_tune

    z_tune Probationary Member

    26
    0
    Joined Nov 3, 2011
    Fort Collins, Colorado
    Here's a video:
    99 eclipse gst idle problem - YouTube

    You can hear how the idle dips real low after I rev it in the video

    There is a loud hissing when I rev it which I always thought was the turbo but I've been researching and it sounds like it could be an intake manifold leak?
    I dunno tell me what you guys think
     
  12. feardafish

    feardafish Proven Member

    61
    1
    Joined Feb 4, 2006
    Cary, Illinois
    Dunno, that ticking sounds like it may just be your injectors. Check your ISC for proper functionality, and do your boost leak test. Also check your ECU for busted or leaky capacitors, those tend to go if the ISC isnt functioning properly.
     
  13. z_tune

    z_tune Probationary Member

    26
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    Joined Nov 3, 2011
    Fort Collins, Colorado
    Thanks for the help guys I will be testing my isc soon. Hopefully thats the problem
     
  14. z_tune

    z_tune Probationary Member

    26
    0
    Joined Nov 3, 2011
    Fort Collins, Colorado
    Alright guys so I finally got around to testing my isc and just to make sure I did it correctly I tested 1-2 2-3 then 4-5 5-6. All of them were at about 42 ohms. Is this within acceptable range? I read it should be around 40 on dsmisc.com

    FYI I have the black plastice isc motor
     
  15. 21_Eclipse

    21_Eclipse Proven Member

    62
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    Joined Jan 7, 2012
    Van Nuys, California
    Where is the isc located? And how do i check it?
     
  16. tcbikerguy6

    tcbikerguy6 Proven Member

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    Joined Apr 24, 2008
    Louisville, Kentucky
    main page
     
  17. The Great White

    The Great White Proven Member

    34
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    Joined Aug 9, 2011
    Upton, Massachusetts
    I'll be interested to hear what you find z-tune. I literally have all those same exact problems. Be sure to post what fixes the problem if you come across what is causing it.
     

    452  0

    1997 Mitsubishi Eclipse GST
    · 2G DSM
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  18. z_tune

    z_tune Probationary Member

    26
    0
    Joined Nov 3, 2011
    Fort Collins, Colorado
    Definitely will let you know. I was going to clean my throttle body this weekend but the Colorado weather says otherwise :mad:
     
  19. Abe'sGST

    Abe'sGST Proven Member

    515
    1
    Joined Aug 27, 2011
    Goldsboro, North Carolina
    whenever you get a chance do clean out the throttle body, that may help you out some, but also check and fix any leaks (exhaust, intake, vacuum and boost)
     

    527  0

    1995 Mitsubishi Eclipse GST
    · 2G DSM
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  20. The Great White

    The Great White Proven Member

    34
    0
    Joined Aug 9, 2011
    Upton, Massachusetts
    Yeah I'm in the same boat, gonna clean the throttle body and probably my MAF this weekend. I peaked under my car the other day tho when it was cold out, so I can see any noticeable leaks, using the cold weather to my advantage. Sure enough, I have a nasty exhaust leak and could see a bunch of air dumping out before the muffler, pretty much all the way down my exhaust. So like the other guy said maybe check that too.
     

    452  0

    1997 Mitsubishi Eclipse GST
    · 2G DSM
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  21. z_tune

    z_tune Probationary Member

    26
    0
    Joined Nov 3, 2011
    Fort Collins, Colorado
    Alright I had some free time today so I decided to throw in the isc I got from dsmisc despite what I think getting good readings from my old isc. I put the new one in (which read a bit over 38 ohms) with a new o-ring and so far it seems to have fixed the idle. I'm so freakin happy this has been bugging me for so long! Idle is solid a bit over 500 and never dips below that. Now from my understanding if this isc goes bad my ecu is bad so we'll see.
     
  22. theoutlaw82

    theoutlaw82 Proven Member

    52
    0
    Joined Aug 25, 2009
    Gulfport, Mississippi
    Sounds like your catalytic convertor is going bad. Thats why you have the bad smell and also low idle and stalling. When a cat starts to plug the enine isn't pushing enough air at idle to breath through it so it starts to stall at low rpms.
     
  23. WES_393

    WES_393 DSM Wiseman

    3,125
    59
    Joined Jun 6, 2011
    Colo Spgs, Colorado
    Yes, a bad ISC can burn up a daughter board in the ECU. I would pull the ECU and check for any burns or corrosion. 500ish is still low for idle. The ISC should be able to keep it around 900 warmed up.
     
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  24. jb2zero0six5

    jb2zero0six5 Proven Member

    224
    3
    Joined Jun 25, 2007
    Sioux Falls, South Dakota
    Doesn't anyone BLT anymore?
     

    464  0

    1990 Eagle Talon TSi AWD
    · 1G DSM
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  25. brownie956

    brownie956 Proven Member

    32
    0
    Joined Sep 19, 2011
    Edinburg, Texas
    Before assuming your ISC is at fault, be sure you have no major wiring/harnesses unplugged. My radio deck all of the sudden crapped out on me, so I took it out to have it tested where I bought it. After they had tested it, I left it aside without plugging the harness or power cable back in. That night and the following day I had low idling around the 350-500rpm neighborhood. The day after, I plugged it back in and got everything back together. I no longer have a low idle issue. Not entirely sure if the battery is excessively stressed because of this or what the deal is, but it fixed it. This is the first time I've ever had an issue with idle, and the first time I've left my deck unplugged, so it's highly unlikely it is coincidence.
    Also, be sure to troubleshoot your low idle issues when the car is thoroughly warmed up, as it will obviously idle higher than normally when in warm up mode. AC off, defrost off, and your wheels turned straight in a manner that won't cause the ECU to increase engine speed.
    The service manual calls for a normal idle operation of 750rpm, +/-100rpm.
     

    320  0

    1999 Mitsubishi Eclipse GST
    manual · 2G DSM
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