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Thread: AFR running really lean on acceleration. Datalog Attached

  1. #1

    Default AFR running really lean on acceleration. Datalog Attached

    Hi all. I have a '79 Bronco with a 545. I have had the 4150 Holley Sniper on it for half a year now and it has been running great. Recently I took it out for a spin and when I give it a good amount of throttle the AFRs go lean. I thought it was maybe the WBO2 sensor so I disabled it and it may have gotten a little better, but didn't fully fix it. I just ordered a new WBO2 sensor to try it and if it's not it, at least I have a backup. I attached the datalog to see if you experts can give me some help. Nothing else has changed on the setup.

    Things to note. I recently raced it at a track and put some 110 race gas in it. Maybe that messed something up? I run 91 in it all the time and maybe only have one tank of 91 through it after the 110/91 mix has gone through it. Also the MAT sometimes reads negative at first startup, but if I shut it off and restart engine it reads normal. Any help would be greatly appreciated. Let me know if the datalog isn't showing up. Thanks!
    Bronco545a.zip

  2. #2
    Join Date
    Dec 2009
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    Connecticut
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    Quote Originally Posted by Lsandell77 View Post
    Also the MAT sometimes reads negative at first startup, but if I shut it off and restart engine it reads normal.
    Contact Holley Tech Service (LINK). The Sniper EFI IAT sensor is a circuit board sensor that measures one throttle bore.
    Also, ensure there are no exhaust system leaks upstream of the WBO2 sensor, and the fuel pressure is still 58-60 psi.

    Originally Posted by Danny Cabral
    Sniper EFI Replacement Sensors - Auto Parts Store
    CTS Sensor: Standard Motor Products TX3
    TPS Sensor: Standard Motor Products TH191
    IAC Motor: Standard Motor Products AC416
    WBO2 Sensor: Bosch 17025, 0258017025 (LINK/LINK/LINK/LINK)
    (The Sniper EFI 2 bar MAP sensor is internal with the ECU.
    The Sniper EFI IAT sensor is a circuit board sensor that measures one throttle bore.)
    Innovate Motorsports HBX-1 Heat-Sink Bung Extender is great for protecting the WBO2.
    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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    Was the racing 110 leaded? May have messed up the WBO2 sensor. If the WBO2 sensor was going south it could have corrupted the Learn Table.

  4. #4
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    I was thinking the same thing. Check the Learn Table: http://forums.holley.com/showthread....1842#post61842 (Learn Table - Diagnostic/Troubleshooting Tool)
    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.

  5. #5

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    Quote Originally Posted by Danny Cabral View Post
    I was thinking the same thing. Check the Learn Table: http://forums.holley.com/showthread....1842#post61842 (Learn Table - Diagnostic/Troubleshooting Tool)
    The 110 fuel was definitely leaded. Will that mess up the WBO2 sensor to where I need to replace it? Or do I need to mess with the tune? Can I clean the WBO2 sensor?

  6. #6
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    Quote Originally Posted by Lsandell77 View Post
    The 110 fuel was definitely leaded. Will that mess up the WBO2 sensor to where I need to replace it?
    Yes, leaded race fuel will eventually foul a WBO2 sensor.

    Or do I need to mess with the tune?
    If it corrupted the Learn Table, Clear the Learn Table or upload the last known good Config File.

    Can I clean the WBO2 sensor?
    No.

    Corrective Action For Failed Wideband O2 Sensor:
    If you suspect a failed WBO2 sensor, and your Fuel Table is well tuned, you can disable Closed Loop (in System Parameters),
    and the engine should run fine until a replacement WBO2 sensor arrives. You can do this to determine if the WBO2 sensor is at
    fault (at least at idle), because in Open Loop mode, the ECU ignores the WBO2 sensor. So if the engine starts running good in
    Open Loop mode, you've found the problem. Just ensure that you don't disable Closed Loop mode while the Learn Table is
    corrupted from a failed WBO2 sensor. Clear the Learn Table (if the percentages are erroneous from their nominal values), or
    load the last "known to be good" Global File. Also, if the ECU detects a WBO2 failure, it will go into Open 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.

  7. #7

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    Well I'm on the way to pickup another WBO2 sensor. Thanks for all the help!
    PS: Will octane booster mess up the WBO2 sensor as well?

  8. #8

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    There are some hints in your datalog, but I'm not 100% sure what's going on. Do you have a fuel pressure gauge? If not, you need one since you could be running out of fuel pressure at WOT. Another possibility is that you have a wideband O2 sensor issue, so you should start fresh with a new wideband O2 sensor. You are hitting the Limits on Learn & Closed Loop Comp so that tells me that your Base Fuel Table is wrong. The engine will never be able to hit the requested AFR if the Base Fuel Table is wrong and the Limits are too low.

    If you know what you're doing with a laptop you can add fuel to the Base Fuel Table. If not, then the easy thing to do is to Transfer Learning To Base. I'd suggest Transferring Learning To Base, install the new wideband O2 sensor, and install a fuel pressure gauge.

  9. #9
    Join Date
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    Ct
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    Some octane boosters are not safe for WBO2 sensors. VP brand is one that is not safe.

    Keep in mind a lot of these store bought boosters don't actually increase the octane by a point. It's more like a tenth of a point. I read something somewhere about it I don't have the link handy.

  10. #10

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    I'd quit messing with the octane booster or 110 and just run E85, if you can get it.

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