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ECMlink Dreaded idle surge after AEM wideband install?.?

Posted by Sbgriffin, Apr 1, 2019

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  1. Sbgriffin

    Sbgriffin Proven Member

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    Lewiston, Idaho
    So my car has been down for a few weeks doing a few upgrades, and a heater core replacement. Installing a new AEM uego wideband, and wiring it in to be logged. Also using link to simulate the narrow band signal. Like already stated, I decided to also tackle my heater core replacement. So needless to say, I definitely had things tore down. Heater core jobs can really suck LoL.
    So after getting things buttoned back up, I've had nothing but issues get my car running properly again. First I found I had a bad ground at the CAS circuit, and had to supplement a new one. Haven't really found a reason why on that issue. Now my car is idling really high, and then starts surging after a few minutes. Looking at my logs, it's also showing A/F ratio isn't matching what the gauge is saying. And once it starts surging, it goes completely lean to rich over and over. I'm really not sure what to think about it. It could be a bad o2 sensor, but that wouldn't make it idle high, or surge I don't think? Maybe the IAC is bad, but I replaced it a few years ago. Anyone have any ideas here, I'm getting extremely frustrated with this nonsense. Seems like my car's cursed lately.
     

    Street Build 816  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  2. bastarddsm

    bastarddsm Supporting Vendor

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    Mendota, Illinois
    turn off closed loop at idle. Tune it to quit surging. Lean or rich afr can cause it to surge, the latency in a wideband does not help, and can actually drive the surging worse. Also play with ignition timing. Try and dial in a bit of negative feedback on the ignition timing.
     

    Showcar Build 5K  1

    1991 Eagle Talon N/T
    9.805 @ 144.00 · 1G DSM
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  3. Sbgriffin

    Sbgriffin Proven Member

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    Lewiston, Idaho
    Well I can definitely give that a try tomorrow. I think also just for piece of mind, I'll unscrew my wideband and test it. Using the brake cleaner and rag trick. Make sure it's responding reasonably. I really think I might have several issues going on here.
     

    Street Build 816  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  4. Sbgriffin

    Sbgriffin Proven Member

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    Lewiston, Idaho
    So the more I think about it, the more I'm convinced it has to be a vac/boost leak. Thats the only thing that can make the rpm's go up that high. When I have it set to target 850, and verified that the throttle plate is closed all the way. And it almost has to be after the throttle body. I'll do a boost leak test first thing tomorrow. That has to be it?.
     

    Street Build 816  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  5. Macgyver'sDSM

    Macgyver'sDSM Proven Member

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    On the lake, Wisconsin
    I would check the timing in the low load cells . I had the same problem and setting them all even at idle helped quite a bit. Any exhaust leak can cause massive fluctuations in your wideband. You can monitor your iac value with link to get an idea of what it is doing.
     

    Street Build 2K  10

    1995 Eagle Talon TSi
    awd · manual · 2G DSM
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  6. 1990TSIAWDTALON

    1990TSIAWDTALON Moderator

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    Independence, Kansas
    And base timing - set it at 5*, TPS calibrated on the car not through Link.
     

    294  17

    1967 Chevrolet Camaro RS
    rwd · automatic · Misc Vehicles

    Street Build 409  4

    1998 Eagle Talon TSi
    fwd · manual · 2G DSM

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    1992 Eagle Talon TSi AWD
    awd · automatic · 1G DSM

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    1990 Eagle Talon TSi AWD
    13.620 @ 108.460 · 1G DSM

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    1990 Eagle Talon TSi AWD
    13.612 @ 107.760 · 1G DSM
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  7. tk106

    tk106 Supporting Member

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    Cincinnati, Ohio
    I'm guessing it was fine before heater core and install WB??? I'd start by checking your vacuum line to boost gauge.
     

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    2000 Jeep Cherokee Sport - Classic
    awd · automatic · Misc Vehicles

    112  4

    93 Civic 4 Door -sold-
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  8. bastarddsm

    bastarddsm Supporting Vendor

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    Mendota, Illinois
    there is 2, well multiple types of idle surge.

    1. Mechanical issues - when you have the biss set too far open, or some type of vaccum leak, and the IAC can't close enough to bring idle speed down, and it hits the "idle rev limit fuel cut" Engine build speed, hits that limit, shuts off fuel, rpm falls below the threshold, and fuel is turned back on. There is some hysteresis in there to reduce the cycle time.

    2. Tune related - The IAC is slow to react compared to the engine. Also the wideband is VERY VERY slow compared to the ecu, engine, and even the narrow band. Like 10X slower than a narrow band at least. That type of latency can drive oscilation. Remember that idle speed is accieved by a balance between the power required to overcome friction and parasitic losses, and the power the engine produces. Think of the IAC/BISS as power not speed. As engine speed increases the torque required to overcome friction/parasitics increases, along with the speed thus power goes up. But remember that while the biss/iac opening is airflow/power, AFR and timing is how efficiently that air flow is turned into power.

    So say your engine speed is high, and say the AFR is rich, and the timing is retarded, the iac closes, and this then drops us into a part of the maps that the AFR and timing is spot on. We could potentially make more power at the same IAC opening, thus resulting in an increase is engine speed. Couple this with a wideband that updates way after the fact, and you can see how the tune can really drive idle speed oscilation.
     

    Showcar Build 5K  1

    1991 Eagle Talon N/T
    9.805 @ 144.00 · 1G DSM
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  9. tk106

    tk106 Supporting Member

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    I'll change my guess and go with narrow band. Switch it back and see what happens. That makes the most sense if it was fine before the install.
     

    71  3

    2000 Jeep Cherokee Sport - Classic
    awd · automatic · Misc Vehicles

    112  4

    93 Civic 4 Door -sold-
    fwd · manual · Misc Vehicles

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    1992 Eagle Talon TSi AWD
    12.625 @ 111.42 · 1G DSM
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  10. bastarddsm

    bastarddsm Supporting Vendor

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    Just turn off closed loop and see what happens first. I'm not saying it can't work, I'm just saying that it can cause problems.
     

    Showcar Build 5K  1

    1991 Eagle Talon N/T
    9.805 @ 144.00 · 1G DSM
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  11. ChessmoDSM

    ChessmoDSM Supporting VIP

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    Burlington, Vermont
    I have been told by numerous reputable remote tuners not to use the wideband simulation, they have all had me turn that off and just use the front 02 (1G) when tuning with ECMlink..
     
  12. tk106

    tk106 Supporting Member

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    I was contemplating using narrow band when I installed my WB and decided against it. Mainly because if the WB sensor ever stopped working or the calibration was off, the car would still run properly. But I'm sure there are guys running it that way without an issue.
     

    71  3

    2000 Jeep Cherokee Sport - Classic
    awd · automatic · Misc Vehicles

    112  4

    93 Civic 4 Door -sold-
    fwd · manual · Misc Vehicles

    Street Build 1K  6

    1992 Eagle Talon TSi AWD
    12.625 @ 111.42 · 1G DSM
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  13. Sbgriffin

    Sbgriffin Proven Member

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    Lewiston, Idaho
    Yes, all was well before I went down this rabbit hole. Also I did the wideband install first, and started it. Only ran it for a short cycle, but it wasn't idling that high.

    Yeah so I'm pretty sure this is a mechanical issue, not tune. The reason I think this is, prior to it getting to the idle surge. It's idling up around 1800-2000rpm, it use to idle around 1200 at first, then settle down quite quickly to 900-1000. Then settle into closed loop idle at 850. So to my knowledge, the only thing that can cause this, after you confirm the throttle plate is all the way closed, is air getting past the throttle plate by a vacuum leak, or IAC. Then once it gets to far out from the target idle, it's starts surging. Definitely from fuel cut, you can see it on both the wideband and my logs. So I just did a boost leak test, and all is well. So maybe the IAC is bad?? Guess I should test it. Also just FYI, the TPS is dialed in, and timing is set to exactly 5°btdc. Prior to my work, the biss screw was set to 30 using link.
     

    Street Build 816  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  14. Sbgriffin

    Sbgriffin Proven Member

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    Lewiston, Idaho
    So I just went out and unscrewed my wideband sensor, and tested it using brake cleaner. And I'm not getting it to go rich, it only goes completely lean then won't respond. So I'd say I have a bad sensor, wouldn't you guys think the same?
     

    Street Build 816  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  15. Sbgriffin

    Sbgriffin Proven Member

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    This is the test I'm using, but not getting the same result.
     

    Street Build 816  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  16. motomattx

    motomattx Proven Member

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    Did you by any chance delete the coolant lines from the throttle body during your heater core replacement? they need to be connected unless you block off the fiav. If they are still connected you might have to bleed the air out of the fiav coolant lines.
     

    Drag Race Build 2K  16

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  17. Sbgriffin

    Sbgriffin Proven Member

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    Lewiston, Idaho
    I actually blocked off my fiav several years ago, and looped the lines. Haven't had a problem with that mod, seems to work just fine with only the IAC regulating my idle. I'm really leaning towards having a bad o2 sensor, right out of the box. I just can't understand how that would raise my idle, might have 2 separate issues?.?
     

    Street Build 816  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  18. motomattx

    motomattx Proven Member

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    Did you actually install a block off plate?
     

    Drag Race Build 2K  16

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  19. Sbgriffin

    Sbgriffin Proven Member

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    Yes, it's the version that still leaves previsions for IAC to work. It's worked well for me.
     

    Street Build 816  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  20. motomattx

    motomattx Proven Member

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    Have you tried blocking off the iac port in the throttle body? a piece of gorilla tape would work as long as you dont try to rev it at all, just a quick test to see if its iac related, in fact I would block the fiav and isc ports off just for checking.
     

    Drag Race Build 2K  16

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  21. Sbgriffin

    Sbgriffin Proven Member

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    Lewiston, Idaho
    Yeah that's a good idea. I did try unplugging the isc, with no luck. But really that probably isn't a good test for anything, because I'm sure it could be stuck open. I think I'll do that tomorrow, along with an ohm test. Thanks.
     

    Street Build 816  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  22. ChessmoDSM

    ChessmoDSM Supporting VIP

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    Stupid question but did you calibrate the WB 02 sensor before installing per procedures? If you did, have you tried to re-calibrate the 02 sensor, I know you just did the "bench" test so this one might just be bad, but make sure you calibrate a new one properly if you didn't the 1st time..
     
  23. Sbgriffin

    Sbgriffin Proven Member

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    Lewiston, Idaho
    AEM widebands are nice for that reason, they don't ever need calibrated in open air. They a chip on the O2 harness that takes a sample of air every time it's powered up. Also the brake cleaner o2 test I posted up above didn't work on my sensor, which lead me to believe it was bad. That was not the case. I decided to try the same test, only with a gas can that was half empty. Just putting the sensor tip into the can made go completely rich. Take it out, it goes lean. The funny thing is, that YouTube video was produced by AEM. But it didn't work with my AEM wideband.
    So I decided to go ahead and test the ISC. Both with my multimeter, and cycling the key on with it removed. And although the coils ohmed out ok, it doesn't move when powered up. You can hear it try, but no real movement. So anyway I'm convinced that the root of my issue. I guess I need to source a replacement, maybe just a OEM used one. I may still have a second issue, I guess we'll see. Thanks to everyone who chipped in ideas and suggestions on this. This forums is still a awesome resource.
     

    Street Build 816  22

    1991 Eagle Talon TSi
    fwd · manual · 1G DSM
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  24. We're on Boost

    We're on Boost Proven Member

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    Seattle area, Washington
    AEM is annoying sometimes.

    When my ISC went bad it still tested fine in the Ohm test, just like what you are saying.
    I would not waste my time buying a used one. Get a new one while they are still available, and before the new prices go any higher.
    Right now from Rock Auto you can get a new one for:
    $69.79 (Standard Motor Products AC146)
    or
    $157.99 (WVE/AIRTEX/WELLS 2H1098)

    I am using the Standard Motor Products AC146 in my car and it is good. When I bought mine the Airtex/Wells was only about $70 but their price has gone wacko since then.

    The drill-down in Rockauto goes like this: Eagle, 1991, Talon, Turbo, Fuel and Air, Idle Air Control Valve.
    Here's a link that should take you right there.

    https://www.rockauto.com/en/catalog...,fuel+&+air,idle+air+control+(iac)+valve,6072
     
    Last edited: Apr 3, 2019

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    1990 Eagle Talon TSi AWD
    650 whp · 510 lb/ft · 1G DSM

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  25. We're on Boost

    We're on Boost Proven Member

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    Seattle area, Washington
    By the way, the most accurate video I've ever seen for watching (and hearing) proper movement of a new 1g ISC is ..... my video haha!
    Which is on YouTube here:


    On the video, it helps to read the description field, which is "Show More" on a PC, or on a cell phone it is just a little down arrow.

    Watching this video, I noticed something I had never seen discussed before. So we had some discussion about that starting in post #8, in this thread: https://www.dsmtuners.com/threads/1990-isc-motor-–-reverse-polarity-for-new-part.514056/
     
    Last edited: Apr 3, 2019

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