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Thread: Seasonal Idle Fine Tuning

  1. #1

    Default Seasonal Idle Fine Tuning

    At the point where I'm doing very few hardware mods to the car, so my hobby this next summer will be making what I've got work better.

    One of the improvements I want to tackle is idle quality, specifically the idle quality changing from season to season (with the weather). Every summer I have to crack open the throttle blade a bit, and every fall I have to close it down a bit. And idle fuel trims lean out in summer and get richer in fall, but the rest of the fuel map is just spot on all year with a fantastic tune.

    Question: What exactly is the Barometric Pressure used for in the HP EFI software? I'm getting the idea that it isn't used for anything. Is that right? I'm guessing that's one of the fine details I need to work in myself using custom tables.

    Question: Does the software use IAT for anything other than the user programmed table of fuel compensation vs. air temp? If that table is really the only thing that matters, then I better spend more time fine tuning it. Any hints about that are welcome. I know I can tune it pretty easy when IAT is near ambient. The real trick is figuring out table values for high IAT temps while idling and stop/go traffic. Thanks for the help!
    Last edited by Qwktrip; 02-28-2020 at 01:51 AM.

  2. #2
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    Quote Originally Posted by Qwktrip View Post
    Question: What exactly is the Barometric Pressure used for in the HP EFI software? I'm getting the idea that it isn't used for anything. Is that right?
    Correct: https://forums.holley.com/showthread...057#post222057 (Related Forum Post)

    Question: Does the software use IAT for anything other than the user programmed table of fuel compensation vs. air temp? If that table is really the only thing that matters, then I better spend more time fine tuning it. Any hints about that are welcome. I know I can tune it pretty easy when IAT is near ambient. The real trick is figuring out table values for high IAT temps while idling and stop/go traffic.
    http://forums.holley.com/showthread....7913#post67913 (Air Temperature Enrichment % Table Tuning)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

  3. #3

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    For IAT, I usually just do a straight slope of 110% to 84% and fine tune from there. Another thing you can do is turn Learn off if IAT gets too hot or too cold. I bet getting this closer to ideal will help your fuel trims.

    What you're experiencing is the limitation of Holley's fuel model. You can get around it by referencing BARO in Advanced Tables. One thing you could try is an IAC Offset with BARO for idle. Leave it in the fall setting, but for summer offset the IAC a bit with lower BARO numbers. It shouldn't take much.

    Curious what engine this is and what timing you're running at idle? I find most people run too much timing and not enough air. Usually when I'm done a remote tune (I do a lot of work on idle) a lot of issues disappear by simply addressing the relationship between throttle position, IAC & timing.

  4. #4

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    It's an LS7 short block with Tony Mamo ported Trick Flow heads, MSD intake, and 240°/254° 114° cam, and a manual transmission. Being choked some by a single 3.5" exhaust, but that's just the way it is in my chassis. I've attached a copy of the tune (it's in V4).

    You actually did the IEA table for me (thanks again!). Idle is something like 17° at 1050 RPM if I remember right. Nick Williams 102mm cable throttle body with a 1/8" hole drilled through the blade (needed the air flow). LS1 F-body IAC valve is teetering at 0% when warm. Engine is not happy when IAC is set to 5%, at least not with any tune settings I've ever tried.

    I have Closed Loop and Learning clamped down pretty tight. I think Closed Loop Limits are 5%, and Learning is disabled right now. Just enough CL Compensation to give me some feedback to help me dial in the fine details.

    This is now the 2nd LS engine in my car. I took all the things I learned from the first 427 stroker and applied it to this LS7 and it's been a pretty good experience so far. I'm down to the little details and not really struggling with any kind of real problems.
    Attached Files Attached Files
    Last edited by Qwktrip; 03-01-2020 at 12:46 AM.

  5. #5

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    So I'm guessing the "Coolant Temp Enrichment" table is in effect when in Open Loop mode, and the A/F Ratio Offset table is in effect when in Closed Loop mode. I've been doing cold start tuning in the "Coolant Temp Enrichment" table while in Open Loop. Is there some kind of quick math I can do to make an equivalency in the "A/F Ratio Offset" table so the two tables result in the same outcome?

  6. #6

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    Quote Originally Posted by Danny Cabral View Post
    http://forums.holley.com/showthread....7913#post67913 (Air Temperature Enrichment % Table Tuning)
    Nice. Added graphs to the worksheet and some math functions to interpolate values for my temp scale, and updated my tune. Hopefully that will be a better starting point than where I was.

  7. #7
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    Quote Originally Posted by Qwktrip View Post
    So I'm guessing the "Coolant Temp Enrichment" table is in effect when in Open Loop mode, and the A/F Ratio Offset table is in effect when in Closed Loop mode.
    No, both functions (Coolant Temp Enrichment % & A/F Ratio Offset) can happen in Closed Loop mode.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

  8. #8

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    Isn't that like double counting for the same factor? Why would you want it that way?

  9. #9

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    Quote Originally Posted by Danny Cabral View Post
    Correct: https://forums.holley.com/showthread...057#post222057 (Related Forum Post)
    http://forums.holley.com/showthread....7913#post67913 (Air Temperature Enrichment % Table Tuning)
    So I read both threads. It begged the question in my mind; Why not just abandon (zero out) the Air Temp Enrichment table native to HP EFI, and instead make a custom Advanced 2D Table for Fuel Compensation with axis of Baro vs. IAT? Seems the basic equations are provided in the article linked above. And combining multiple factors into a single table should make tuning easier because you're adjusting one value instead of two separate values in two different tables.

    This is a worksheet I put together in Excel with fuel compensation percentages relative to STP (sea level and 15°C). Pressure scale is built off equations at the Wiki site for atmospheric pressure, https://en.wikipedia.org/wiki/Atmospheric_pressure

    I can offset this entire table based on whatever Baro and Temp was present when I had my car tuned (I've got the datalog to reference).

    Last edited by Qwktrip; 03-01-2020 at 03:56 AM.

  10. #10
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    Quote Originally Posted by Qwktrip View Post
    Isn't that like double counting for the same factor? Why would you want it that way?
    I was replying to the Open/Closed Loop (CTE & AFRO) remark without an Advanced 1D/2D Table. If you prefer using an Advanced 1D/2D Table for IAT/MAT Correction, you'll need to experiment with it. I have no need for that, the Air Temperature Enrichment % table works fine for me.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

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