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ECMlink Guys running W/O IAC/FIAV get in here!

Posted by DROPthatCLUTCH, Apr 16, 2016

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    DROPthatCLUTCH Proven Member

    Joined Feb 21, 2011
    Calgary, AB, Canada
    Weirdest thing happened the other week.. Car has been running great all year until I replaced the CAS o-ring. Yes I set base timing back to 5* BTDC with a timing light. Yes the notch inbetween 10BTDC and T. Yes I grounded the timing connector via ecmlink. Yes I installed the CAS with the notches lined up while cylinder 1 was at TDC on compression stroke.

    Got crazy idle surge after I replaced that o-ring so I did Terry's idle surge trouble shooting and found my ISC to be bad after a quick continuity test across 1-2, 2-3, 4-5, 5-6. So I priced out a new revised ISC and decided I'd block it off instead.

    After the install of the block off plate it still boosts strong and while I'm actually moving in the car it feels just as it did before, but when I come to an idle it surges 1500-2000 and it's running lean at idle now too after the block and it wasn't before. 18:1 and higher as the idle speeds up, then it cuts fuel, pegs the WB the idle drops and then AFR drops to about 18:1 again. Cruising and WOT AFRs are unchanged from before.

    It only starts surging once its in closed loop BTW. Warms up steady around 1500rpm.

    Boost leak tested and she's tight no leaks, which I already new. So I grounded the timing pin again in ecmlink and started messing with the BISS now that it seems this is my only way of controlling idle mechanically. I have it bottomed out and the surges become less violent and slower but the problem persists.

    What are you guys adjusting on link to steady this out at idle.

    661  1

    1992 Eagle Talon TSi AWD
    awd · manual · 1G DSM
  2. steve

    steve DSM Wiseman

    Joined Feb 3, 2002
    Boulder, Colorado
    Assuming you truely blocked off the FIAV and ISC passages and their not leaking, the only other ways that I can think of that air can reach the cylinders is via the BISS, Throttle Plate, EGR, PCV, Injector seals, gaskets, and a leak in the brake booster.

    With the BISS bottomed out you should be stalling not idling at 1500, so it would seem you're leaking air somewhere.

    Did you use a new lower gasket or RTV to seal the block off plate?
    Is your throttle butterfly closing all the way?
    Throttle Cable have the right slack in it?
    The SIMM kills the potential EGR path.
    Last edited: Apr 17, 2016

    112  4

    2008 Audi TT 3.2 Quattro Roadster
    awd · manual · Misc Vehicles

    78  5

    2002 Audi TT Quattro Roadster 225
    awd · manual · Misc Vehicles

    72  2

    1992 Dodge Stealth RT/TT
    awd · manual · 3000GT/Stealth

    4K  12

    1991 Mitsubishi Eclipse GSX
    manual · 1G DSM

    DROPthatCLUTCH Proven Member

    Joined Feb 21, 2011
    Calgary, AB, Canada
    I used a new OEM FIAV seal with the block off plate no rtv though just slightly lubricated with some sil glide.
    I have previously rebuilt my TB with new shaft seals and BISS o-ring and the butterfly does indeed close all the way.
    Throttle cable is good too in terms of enough slack to allow it to shut while still getting 100% at WOT. Still surges with the cable disconnected and the butterfly forced shut.

    This is random but what happened to MY1GDSM and his tuning services he offered? He helped me out in the past with lots of idle tune issues. He still hang around these parts?

    661  1

    1992 Eagle Talon TSi AWD
    awd · manual · 1G DSM
  4. gsxeclipse102

    gsxeclipse102 Proven Member

    Joined Mar 8, 2003
    carmel, New York
    Deff vacuum leak. With the biss screwed in and no iac the car shouldnt run. Spray silicone spray around gaskets and seals while its idling. When you found the leak you will hear the rpms change dramatically. I would check the block off plate/ seal first since thats what you changed

    Street Build 3K  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
  5. YZFR1

    YZFR1 Proven Member

    Joined Apr 8, 2010
    Atlanta, Georgia
    To adjust the idle out you could try using your ignition timing. I've been running without ISC/Fiav for about 7 years now but with AEM. There is a table in aem that lets you adjust ignition timing based on idle error. In other words, if my idle drops than it bumps the timing up to an extra 20 degrees. Same thing if idle goes too high, it lowers ignition timing and in turn helps keep it steady.

    I imagine you could do something very similar with Link by tinkering with your base map instead. But like others have suggested, make sure you don't have any leaks.

    The only time I have an issue running no idle speed controller is on cold e85 startups it can be annoying to sit there and feather the throttle so it won't stall. But after it gets going, it's fine afterwards.

    643  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
  6. DSMTyson

    DSMTyson Proven Member

    Joined Nov 9, 2010
    Lake Charles, Louisiana
    ^ Link does vary timing at idle to help stabilize it. But nothing as drastic as 20 degree changes.

    Do a boost leak test and see if your block off plate is leaking. If it is bad enough it can cause a vacuum leak. I had to rtv the side of the block off plate that has no gasket to seal against in order to stop my leak.

    I think you have a vacuum leak.

    1K  0

    1995 Eagle Talon TSi AWD
    manual · 1G DSM
    gsxeclipse102 likes this.
  7. Lester B

    Lester B Proven Member

    Joined Mar 18, 2015
    Fort collins, Colorado
    Did you sort out your idle? I've been battling the same issue. And everything is blocked off of mine as well.
    Good luck.

    1K  0

    1990 Mitsubishi Eclipse GSX
    manual · 1G DSM

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