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Thread: Help with AFR swings during throttle transitions LS1 in track car - causing concern.

  1. #21

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    He doesn't have the FPR vacuum reference, which IMO needs to happen on a road course car.

  2. #22

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    Quote Originally Posted by allan5oh View Post
    He doesn't have the FPR vacuum reference, which IMO needs to happen on a road course car.
    I'm in the process of adding this. There's a 1/2" port on the back of the intake manifold at the MAP sensor, but the port on the regulator is 3/16", so I had to make a hose adapter. My FPR is only about 10" away on the firewall, so this should provide a healthy vacuum reference. I also changed the Minimum Injector Opening Time setting 1.0 msec and will report back shortly. You guys are great. I'm now pretty familiar with the HP EFI software and understand most of the principals, but I don't have any real world tuning experience, so your guidance is really appreciated.

  3. #23

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    Looking at Datalogs I've been concerned about the AFRs swinging pretty wide during throttle transitions. This being a track car throttle transitions are frequent and pronounced.

    With the help of the people here I've made quite a few changes trying them one at a time.
    I'm a novice but from what I can tell all seem logical.

    In no particular order here is a summary of the changes I've made since first posting:

    >The fuel pressure regulator is now referenced to vacuum. Fuel Pressure remains set the same at 45 psi at idle without the vacuum reference connected (recommended procedure on setting it). With the vacuum reference connected the FP varies between 35 & 45 psi and is now at 40 psi at idle.
    > The map and rpm scales have been modified. Since the MAP never gets below 10 kPa having lower values on the scale were eliminated. Same with RPM below 650. I made sure that the fuel map and spark advance from the original tune were carried over correctly.
    > Minor adjustments to the Target AFR Table where made at peak TQ & HP
    > The Minimum Injector Opening has been set to 1 msec
    > The Injector End Angle Table has been enabled. The table was created following the procedure that a lot of folks here have used successfully. This mostly seems to affect idle, and the gas smell is completely gone.
    > The AE vs MAP rate of change table was set to zero
    > The AE vs TPS RoC Blanking was set to 4
    > The AE vs MAP RoC Blanking was set to 7
    > The Coolant Temp Enrichment Table was tweaked
    > The AFR Ratio Offset table was tweaked
    > The Closed Loop and Learn are enabled at all RPM
    > The TPS % to Enter Learn was set to 1% ( I did this since the TPS never gets to zero or below 1% )
    > Some smoothing of the fuel maps was done in VE mode

    I was able to run around the neighborhood this afternoon and drive the car trying to emulate track driving, a few eyebrows where raised for sure.

    Attached is the GF & DL from this adventure and my observations;
    Attachment 8445 Attachment 8446

    1. The engine feel like it is running as strong or stronger than it ever has, it starts & idles fine.
    2. Throttle response feels really improved, it also seems to rev much quicker and feels like it may be pulling stronger
    3. Gas smell at idle is gone
    4. On occasions there was hesitation coming off throttle and then getting back on, this feel like it may be gone completely along with a very infrequent / rare back-fire
    5. In general there appears to be no stumble when coming off throttle as when slowing to come into the pit, no back-fires or pops
    6. It looks like it’s dropping out of learn for no apparent reason under certain conditions
    7. The AFR still goes lean when the MAP goes high & RPM are increasing, although not as lean as before
    8. The AFR does not go nearly as rich as it was before when coming off throttle and RPM are decreasing so this looks much better

    This was only a 5 minute drive and I’m sure there is a lot more learning that will take place. My only concerns now are 6 & 7 above. I'm planning of going to the track next weekend and letting the learn do it's thing then see were I'm at.

    A few questions before I do.
    Is this safe to run? Should I now just try adjusting the fuel map and smoothing in VE mode? Thanks, Dan
    Last edited by LS1Z3M; 07-15-2019 at 12:11 PM.

  4. #24

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    Why the hole in your Base Timing Table? Stabbing your throttle, you're dropping to 18° timing from 30°-35° base. I'd go to 100% in Coolant Temp Enrichment when engine is at operation temp (160°F-180°F), so your Learn does start to chase itself.

  5. #25
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    Read 4th & 5th paragraphs: http://forums.holley.com/showthread....2523#post62523 (Holley EFI Tuning Tips & Information)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, 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.

  6. #26

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    Quote Originally Posted by Danny Cabral View Post
    Read 4th & 5th paragraphs: http://forums.holley.com/showthread....2523#post62523 (Holley EFI Tuning Tips & Information)
    I went back over the entire fuel map enlarging a 5 x 5 cell section at a time and smoothed out the entire Base Fuel Table switching over to VE% as described. It was surprising to see how much additional smoothing could be performed. Thanks Danny for pointing this out to me. I spent hours doing this and it's a good as I'm going to get it. Guess it's time to run it again, get some data and see where it's at.

    Quote Originally Posted by Timjus View Post
    Why the hole in your Base Timing Table? Stabbing your throttle, you're dropping to 18° timing from 30°-35° base. I'd go to 100% in Coolant Temp Enrichment when engine is at operation temp (160°F-180°F), so your Learn does start to chase itself.
    Not sure what you're referring to. The Base Timing Table is very close to what Holley provides for an LS base and the lower advance number you mentioned is in the idle range and not affecting the AFRs in the normal operating range for the engine. Also, all data is with the engine warmed up to 160°F or higher where the CTE is already at 100%.

  7. #27
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    Quote Originally Posted by LS1Z3M View Post
    It was surprising to see how much additional smoothing could be performed. Thanks Danny for pointing this out to me.
    You're welcome.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, 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.

  8. #28

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    Do you think it'll be safe to run this tune to allow further Learning? I had two BMW engine fail when the tune was super rich and washed out the cylinder walls. It was a different EFI system/engines, and one of the main reasons I swapped in the LS1. So I'm a bit paranoid about the AFR swings during throttle transition and the Learn deactivating at times.

  9. #29
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    Quote Originally Posted by LS1Z3M View Post
    Do you think it'll be safe to run this tune to allow further Learning?
    As long as the Target Air/Fuel Ratio Table is properly tuned, and the WBO2 sensor is functioning properly. Read the links below.

    So I'm a bit paranoid about the AFR swings during throttle transition and the Learn deactivating at times.
    Closed Loop & Learning isn't active during periods of acceleration enrichment or deceleration (zero TPS, 400 RPM above target idle).
    The engine needs to be at "steady-state" RPM for the Learning to function, at lower RPM.
    The Closed Loop Status has many momentary periods when it's inactive (Open Loop mode).
    This is normal due to the TPS & MAP based acceleration enrichment (transient fueling).
    Also, any "noise" on the TPS or MAP signal wire (false Rate of Change) will deactivate Closed Loop.

    http://documents.holley.com/techlibr...__statuses.pdf (Sensor Diagnostics & Statuses)
    http://forums.holley.com/showthread....5760#post45760 (Scroll down to "Learn Issues, Self-Tuning".)
    http://forums.holley.com/showthread....7370#post47370 (Closed Loop & Learn Table - Especially posts #2, #6 & #11.)
    http://forums.holley.com/showthread....ents-Read-This (Initial Checks & Adjustments - Read Steps #1-#6!)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, 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.

  10. #30

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    Quote Originally Posted by Danny Cabral View Post
    As long as the Target Air/Fuel Ratio Table is properly tuned, and the WBO2 sensor is functioning properly. Read the links below.
    I know the Target A/F Ratio table is fine and the WBO2 is as well. I read through the links again and found one thing that raised a question that maybe you can answer.
    The “Advanced Control” section has a drop down with numbers 1 through 5. These are indicative of the “Speed” or “Gain” of the Closed Loop control. Lower numbers create slower Closed Loop response time while larger numbers increase speed.

    In my application where the RPM, TPS & MAP can all be changing rapidly would it be better to:
    A) Slow down the Learn, so it's not chasing these swings an potentially always trying to "catch up"?
    B) Speed up the Learn so it can possible make corrections in these situations?
    I can see an argument for either case, but I'm not familiar enough with how the ECU works to know if this would even make a difference. At present, this control is set to 3.

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