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Thread: AFR Spikes/IAC

  1. #1

    Default AFR Spikes/IAC

    So I'm still having a little bit of a dip at the return to idle, even though I've played with every darn version of IAC that I can think of. Would this potentially help my situation? I'm finally getting relatively comfortable with all the settings, well minus the various AE stuff because I don't completely understand that yet, but I'm unfamiliar with the Advanced Tables. I checked it out based on your post and it looked fairly straightforward, just not entirely sure my situation warrants it. Even with a carb, I always had a dip in the return to idle, unless I messed with the difference between ported & manifold vacuum or adjusted the timing, which would affect my overall, so I typically left it at 12°-13° plus the vacuum advance.

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
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    19,267

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    FYI: I'm not using the Advanced ICF because I had a problem. It's just enhancing the idle/deceleration area.
    You shouldn't need the Advanced 1D/2D Table. This is usually due to a Base Fuel/Timing Table tuning issue.
    https://forums.holley.com/showthread...7694#post97694 (Related Forum Post)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  3. #3

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    Here's my current setup, if you see anything feel free to let me know. I'm going to install a spacer on my dual-plane as well to see what that does. It's not a bad dip and always recovers, just anytime I go into neutral or pull the clutch she'll drop down. I've messed with the IAC a lot, being a manual I'm not happy with a 2.5-3.0 second ramp down at all, so that's the only other thing that may help that I know of.
    Attachment 2746 Attachment 2747 Attachment 2748 Attachment 2749

  4. #4
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    This isn't something I can see from pictures. I can't offer advice when I'm not looking at the data (AFR, Timing, Fuel PSI, etc.). Only knowing the symptoms (stumble, stalling, etc.) doesn't help, because we need to know what's happening with the EFI system during this occurrence. Connect Online with the ECU, and look at where the live cursor moves to when the problem occurs. Is this area too rich or too lean? (You'll have to look at the Learn Table too, since they function as one (LINK), unless you've already Transferred Learning To Base and blended the Fuel Graph smooth.) Ignition timing? Also, ensure the idle speed screw on throttle body, is adjusted to achieve an IAC Position of about 5% at hot idle. Remember to perform another TPS Autoset, whenever you adjust the idle speed screw on the throttle body. If necessary, record & review a datalog of this issue.
    http://forums.holley.com/showthread....ents-Read-This (Initial Checks & Adjustments - Read Steps #1-#6!)

    Quick Datalogger Information:
    Always provide data, not just symptoms. Is the AFR & ignition timing optimized? Overlay the datalog onto your Global File.
    Ensure the Target A/F Ratio table is properly programmed for your engine. Ensure the ECU is "Learning" (Learn Table LINK).
    Scroll through the datalog to the problem area. Then look exactly where this happens on the Base Fuel & Timing Tables. Scrutinize:
    RPM, MAP, MAT, TPS, CTS, IAC, Target AFR, AFR Left, CL Comp, Ignition Timing, Duty Cycle, Fuel Flow, Fuel Pressure & Battery.

    I find the most helpful datalog function, is overlaying the datalog on your Global File.
    I'm in the habit of using the datalog Overlay feature every time I review a datalog.
    Click on "Datalog" (on the top Toolbar), "Activate Overlay", then "Open Data Log".
    You can literally "playback" a recorded event, and watch it as it happened on any screen.
    Minimize (shrink) the datalog window, and move it to the bottom of any Global File screen.
    Then click & scroll anywhere on the datalog, and watch it playback on your Global File (EFI software).
    http://documents.holley.com/techlibr...9r10543rev.pdf (Holley EFI Datalogger Instructions)
    https://forums.holley.com/showthread...s-amp-Datalogs (Datalog & System Log Information - Read "NOTES")
    https://www.youtube.com/watch?v=iqHO...C6FEA0BB99AF17 (How To Record & Email A Datalog)
    https://forums.holley.com/showthread...7531#post77531 (Closed Loop Datalog Tuning - Posts #2, #4 & #6)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  5. #5

    Default AFR Spikes/IAC

    I've been chasing a problem for a couple months now and have been trying many things based on everyone's advice, and finally got around to datalogging today. I'm hoping someone can point me in the right direction. For the most part these are minor issues, but there is one that's pretty annoying. I've included two datalogs to be perused as well as my GCF.

    If I give it a medium to light throttle, typically at low MAT, the IAC will stick and won't return down quickly or even at all sometimes. This problem didn't appear until the weather in Central Valley Cali started dropping down, during the summer I did not have the problem and it seems to be significantly better on warmer days, but that could be me over thinking it as well. In the DL named BAM you can see I duplicated it twice. You'll notice it when I hit the throttle and then the TPS returns to zero, but the RPM stays between 2-3000 and the IAC stays at the preset percentage (23%). The AFR seems to bounce around a little as well, but I'm super confused as to why the IAC won't return. My IAC at idle is typically between 4-6% warmed up.

    I've also include a DL named light throttle. My AFR is all over the place when I do light throttle or decel for a couple seconds, and then it levels back out correctly. I'm not sure if that is an AE issue or what. My base fuel seems pretty smooth and it will always go back and if I hit the throttle harder it won't do it, it only seems to be with slight to low throttle changes. Here's what I've done:

    I had an atrocious intake leak that blew my gaskets out, I had that on my last thread. I replaced them and have zero intake leaks.
    I have no exhaust leaks before or after the WBO2 sensor.
    I have the HBX-1 bung that Danny recommends as well.
    I have adjusted the settings on the IAC several times, but always end up back to where I'm at now as it does it not matter what.
    I've disconnected the battery for 20 minutes as well, as completely reflashed the ECU to the 110 build.
    Screamed a little as well.

    The only issue I really care about is the hanging RPM. The AFR I would like to learn a little more about fixing, but it always stabilizes.
    When I hit the hard throttle and it gets really rich, it obviously will run pretty rough for a second, but it will level out.
    I keep talking about putting a spacer on my intake, but never do, so I went ahead and ordered one tonight and will install a 1 inch spacer.

    My setup for SA.
    Ford 302
    Terminator TBI
    Weiand Dual-Plane Intake (Machined the divider down to simulate an Air-Gap style and help the MAP signal.)
    Holley Dual Sync Distributor
    MSD 6A CD Ignition Box
    MSD HVC Coil
    T5 Transmission

    I think that's enough for now. I appreciate all the help and really like learning the system, just every now and then she gets quirky and I'm not sure what to do.
    https://www.dropbox.com/s/fhh1vvlyaj...NGES.hefi?dl=0
    https://www.dropbox.com/s/yy67ftl89jmpwdw/BAM.dl?dl=0
    https://www.dropbox.com/s/342qdbolgo...ROTTLE.dl?dl=0

  6. #6

    Default

    Looking at the datalog and the HEFI file, it looks like the IAC Hold Position is too high, or the RPM Above Idle To Ramp Down is too low, in terms of the IAC problem. Also looking through the Help File I found this:
    There is an easy way to set these quickly. Perform the following:
    · With the engine at operating temp and in neutral, determine the engine speed where you want to start the IAC ramp-down (for example 1500).
    · Set the engine idle speed to this speed (1500 for this example).
    Look at the position of the IAC when the engine is running at 1500. For this example, it is 38 (then set the idle speed back to the normal value).
    · Subtract 5 from this value and enter that value for the “IAC Hold Position” (38 – 5 = 33 for this example).
    · Subtract the target idle speed from the ramp down speed above (in this example 1500 – 800 = 700). Enter this value (700) for the “RPM Above Idle to Start Ramp.
    · Then enter a “Ramp Decay Time” as desired. A larger number will take longer to set the engine back to idle speed, a smaller one will return it quicker.
    Performing this method will optimize these parameters.
    If these values are not set correctly, it can cause the IAC to not “count down” and return back to idle. If this is the case, either one of the following needs to be done:
    · Lower the “IAC Hold Position”
    · Raise the “RPM Above Idle to Start Ramp”

  7. #7

    Default

    Quote Originally Posted by SatherCS View Post
    Looking at the datalog and the HEFI file, it looks like the IAC Hold Position is too high, or the RPM Above Idle To Ramp Down is too low, in terms of the IAC problem. Also looking through the Help File I found this:
    I’ll play with it tomorrow, but the settings in there are what Danny told me to use and worked great for about 8 months until this started occurring, I forgot to mention that. However, at this point I’ll try anything to get it to stop!

  8. #8
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    19,267

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    Quote Originally Posted by sr1032 View Post
    The only issue I really care about is the hanging RPM.
    Terminator TBI users may need to also adjust the secondary shaft screw (LINK), so the throttle blades are equally open.
    https://forums.holley.com/showthread...7840#post97840 (Related Forum Thread)

    The AFR I would like to learn a little more about fixing, but it always stabilizes.
    The Fuel Graph might need to be blended smooth.
    http://forums.holley.com/showthread....2523#post62523 (Holley EFI Tuning Tips & Information)

    I keep talking about putting a spacer on my intake, but never do, so I went ahead and ordered one tonight and will install a 1 inch spacer.
    Yes, you should've accomplished this already, since it's well known to compliment the Terminator EFI.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  9. #9

    Default

    Quote Originally Posted by Danny Cabral View Post
    Terminator TBI users may need to also adjust the secondary shaft screw (LINK), so the throttle blades are equally open.
    https://forums.holley.com/showthread...7840#post97840 (Related Forum Thread)
    That's done, I had a huge problem with that originally, but it's been lined up & running good for quite some time there. When it hangs it's clearly the IAC holding the air even though the TPS is at zero. I've even been able to pull over before while it hanged and the throttle blades were closed like they should be. If I put my finger on the IAC it would kill the engine like it should.

    Quote Originally Posted by Danny Cabral View Post
    The Fuel Graph might need to be blended smooth.
    http://forums.holley.com/showthread....2523#post62523 (Holley EFI Tuning Tips & Information)
    I'll continue to play with it. I'm more concerned on how rich or lean it gets on just slight throttle touches, it's a little off there.

    Quote Originally Posted by Danny Cabral View Post
    Yes, you should've accomplished this already, since it's well known to compliment the Terminator EFI.
    Yes you're right, I've got a million excuses, but none of them matter, so I've got one coming in tomorrow. After I get it, I'll play with the settings and go from there.

  10. #10
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    Dec 2009
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    Connecticut
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    Quote Originally Posted by sr1032 View Post
    If I put my finger on the IAC it would kill the engine like it should.
    No, blocking off the IAC air inlet passage should not stall the engine.

    I'll continue to play with it. I'm more concerned on how rich or lean it gets on just slight throttle touches, it's a little off there.
    Acceleration Enrichment can't be tuned until the Base Fuel Table is well tuned.
    If you have a momentary lean spike, on light throttle acceleration, check
    your AE vs TPS/MAP RoC Blanking values (in Fuel Modifiers/Fuel Control):
    If they're 15 & 7, those are the old values from the V1 ECU firmware.
    Change the AE vs TPS RoC Blanking value to 4-6.
    Change the AE vs MAP RoC Blanking value to 5-7.
    Some users reported the need for an even lower TPS RoC Blanking value.
    Ensure there's no TPS/MAP RoC signal activity at idle, due to noise/kPa fluctuation.
    http://forums.holley.com/showthread....1379#post61379 (AE Tuning Information)
    http://forums.holley.com/showthread....7925#post47925 (Additional AE Tuning Information For Stubborn Engines)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

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