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Thread: AFR/Idle Question, Possible Issue

  1. #21

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    Yes, it's enabled, and yes, it's Learning. It was unchecked to see how it would run in Open Loop.

    Holley wants me to send my ECU in to them. I'm going to try some more things first before I do that, but they seem to be out of ideas at this point. I have a friend who has a Terminator Stealth who's up for letting me try his throttle body on my setup, so that's a tempting option as well.

    No, I don't need to go into the secondary adjustment. I think I worded my question poorly, I actually mean as an additional question not a secondary specific question, sorry. It was more to reaffirmation that I probably need to go to a cable setup, as my accelerator rod doesn't have the leverage to pull the primary & secondary blades all the way vertical. Obviously the TPS goes off whatever movement it sees, so it's not getting the full range of motion. I'll deal with that after I figure out what's going on with this issue.

  2. Default

    I had pretty much the same symptoms right before my TPS failed. AFR was swinging from lean to rich just off idle. If you haven't replaced your TPS yet, I would as they don't seem to last long anyway and it's a cheap check. Also replace the spark plugs, just don't check them; too hard to tell just by looking at them. Cheers.

  3. #23

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    I installed another TBI a friend of mine had and it was still doing it. I kinda figured it would, but I wanted some piece of mind for a change. I got the idea to set my timing at a static degree of around 20° and give it a try. Low MAP is basically a light load, so I wanted to see if it had anything to do with the huge spike the timing table had right around where this was occurring. Now the car doesn't have a ton of miles on it, so I don't expect the Learn curve to be perfect yet, but the 300-500 RPM bounce was unrealistic. I fired her up and set the timing at 20° and it was a HUGE improvement. Then I set it to 40° and it did not like that at all, bounced all over the place. So I now am playing a ton with the Base Timing Table and trying to make it much smoother, and then I'll go give it a try again. The way the Base Timing Table had it there was a jump from about 19° to 40° in a matter of 600 RPM and was at 40° by 2000, which is where the bouncing was occurring. I'll keep playing with it, but does that sound right that if my timing was off that much, that it would have a hard timing stabilizing at a particular RPM and cause surging? I'm trying to use the graph mode as well so it looks a bit smoother, thing was all over the place in the graph mode.

  4. #24
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    Quote Originally Posted by sr1032 View Post
    The way the Base Timing Table had it there was a jump from about 19° to 40° in a matter of 600 RPM and was at 40° by 2000, which is where the bouncing was occurring. I'll keep playing with it, but does that sound right that if my timing was off that much, that it would have a hard timing stabilizing at a particular RPM and cause surging?
    Yes, of course! This is what tuning is all about.

    I'm trying to use the graph mode as well so it looks a bit smoother, thing was all over the place in the graph mode.
    Yes, that's a good feature to help blend the timing advance.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 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, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 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 tires.

  5. #25

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    I'm starting to learn the way to try & isolate issues is to check all the tables that have live data, and see where the orange dot moves around. That's actually what got me messing with the timing, since I noticed it was bouncing 20° very quickly. I'm sure the best way to mess with timing would be on a dyno, but I'll just drive around and play with it until it seems smooth enough for government use. Does anyone have a snap shot of their timing table & graph I could look at for examples? Hindsight being 20/20, I probably should've left my old distributor installed until I was done with the tuning, and then swapped in the new Holley dual sync distributor. Lesson learned for sure.

  6. #26
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    Quote Originally Posted by sr1032 View Post
    Does anyone have a snap shot of their timing table & graph I could look at for examples?
    Target AFR Table: http://s41.photobucket.com/user/dcf1...1r64v.png.html (Blue cell is idle.)
    Base Timing Table: http://s41.photobucket.com/user/dcf1...ns3rt.png.html (Blue cell is idle.)
    Base Timing Graph: http://s41.photobucket.com/user/dcf1...d13ks.png.html (Green dot is idle.)
    NOTE: My engine has an 11:1 static compression ratio, high dynamic compression ratio (230° camshaft), 93 octane gasoline.
    NOTE: My LenTech Strip Terminator wide-ratio AOD transmission is a 4 speed overdrive with a non-lockup torque converter.

    Magnifying screen: hold "Ctrl" key & press "+" key.
    Restore: Firefox - hold "Ctrl" key & press "0".
    Restore: Internet Explorer - hold "Ctrl" key & press "".

    AFR: I idle @ 14.2 AFR, cruise @ 16.0 AFR, WOT @ 12.6/12.8 AFR.
    Timing: I idle @ 20°, cruise @ 40° (2700 RPM), WOT @ 35° BTDC.
    I also have an Advanced 2D Table (Timing Offset - RPM x TPS) that adds 4° to the idle timing below 2% TPS & 2 MPH (VSS).
    The slight increase in timing under the idle area, adds timing advance to the deceleration area, as the engine returns to idle.

    http://forums.holley.com/showthread....0449#post30449 (Air/Fuel Ratio & Ignition Timing Tech Articles - Scroll to end.)
    http://documents.holley.com/199r10485rev1.pdf (Holley 534-201 Stand-Alone WBO2 Sensor Kit - Suggested Air/Fuel Ratios, Page 6)
    https://edelbrock-files-v1.s3.amazon...ers-manual.pdf (Read pages 4-10 of this Edelbrock EFI tuning manual, it's very good.)
    https://www.msdperformance.com/suppo.../#TimingCurves (MSD Centrifugal Timing Advance Curve - Chart "C", a good start.)
    https://www.msdperformance.com/suppo...TimingSettings (MSD Tech - Initial, Centrifugal & Total Timing Settings & Terminology)
    http://www.useasydocs.com/theory/spktable.htm (MicroSquirt3 Timing Table Calculator - Theoretical only, use at your own risk.)

    Sniper EFI: Except for the Sniper EFI software, the Target Air/Fuel Ratio Tables & Base Timing Tables in the base calibrations
    (Terminator, HP & Dominator) are better than the typical centrifugal/vacuum advance curves. Using the Sniper EFI software
    (LINK), Fuel ICF - Target Air/Fuel Ratio Table & Spark ICF - Base Timing Table, select the "2D Table" Type (not "Simple") utility.
    The Target Air/Fuel Ratio Table & Base Timing Table can then be properly tuned for any engine.

    Hindsight being 20/20, I probably should've left my old distributor installed until I was done with the tuning, and then swapped in the new Holley dual sync distributor. Lesson learned for sure.
    If you know your previous distributor's ignition timing advance curve, you can enter those numerical values in the Base Timing Table and create a good starting point.

    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 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, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 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 tires.

  7. #27

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    I spent about two hours setting the AFR & timing table today, and then I took a drive. It's still Learning, but a hundred times better that's for sure. Instead of worrying about every little thing, I'm just going to drive it for a few weeks and then I'll fine tune all the fuel & timing and reduce the Learn Limits, I'm no longer freaking out about how big of a pain it is to cruise at low speeds. I'm sure a little bit has to do with my dual-plane, but I'm so much happier now it's not even funny. I'll post of my tables & graphs tomorrow. I rode a 77 mile bike race today, so I'm exhausted at this point. I was able to just go by what my old curve was, and then improve it in a few areas that the distributor couldn't compensate for. How did you get your tables & graphs to be colored like that? Just curious to see if I could do that before posting them, or if it's something about the version you're using.

  8. #28
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    Quote Originally Posted by sr1032 View Post
    I spent about two hours setting the AFR & timing table today, and then I took a drive. It's still Learning, but a hundred times better that's for sure.
    That's good news.

    I'm sure a little bit has to do with my dual-plane, but I'm so much happier now it's not even funny.
    You really should try a 1" open spacer.

    How did you get your tables & graphs to be colored like that? Just curious to see if I could do that before posting them, or if it's something about the version you're using.
    That's the new "Heat Map" feature in the latest Holley V4.0.32 EFI software (LINK).
    It's a colored pattern of the EFI tables. A numerical or pattern error stands out now, making it obvious.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 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, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 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 tires.

  9. #29

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    Here's my setup - Ford 400, 9.5:1 compression ratio, Edelbrock intake, stock exhaust. Sniper EFI controls timing.


  10. #30

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    Dr_Grip, I was looking for some examples of spark tables to help me get a good base line for my 351C. On yours, 40°-43° of advance timing at idle (800-1000 RPM) seems really high. Is that the same value you see on your timing light?
    Last edited by Dan LeBlanc; 11-29-2017 at 09:31 AM.

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