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Thread: AFR stays at 35.6 at idle.

  1. #1

    Default AFR stays at 35.6 at idle.

    EFI was working fine a couple of months ago.
    Fired it up this week and the idle is awful.
    I noticed the AFR was stuck on 35.6 and the unit is sucking air like mad.
    The IAC was was hovering around 70%.
    I've attached the Config File and the datalog that I took.
    1967 Mustang, 408 stroker engine.
    Any help would be appreciated.
    Attached Files Attached Files

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,701

    Default

    Originally Posted by Danny Cabral
    Is the Sniper EFI Learning? Is the ignition timing synchronized? Is the fuel pressure 58-60 psi (LINK)? IAC Position
    of about 5% at hot idle? Check for ignition misfires/RPM signal problems, exhaust leak upstream of WBO2 sensor,
    or if the WBO2 sensor (or other sensor) has failed and corrupted the Learn Table. Look at the Data Monitor/Gauges.
    Also, the Holley Sniper EFI will intermittently inhibit Closed Loop at idle, if the AE vs TPS/MAP RoC Blanking values are set too low.
    http://documents.holley.com/techlibrary_199r11259.pdf (Holley Sniper EFI Help Manual)
    http://documents.holley.com/199r11369.pdf (Holley Sniper EFI Troubleshooting Guide)
    https://forums.holley.com/showthread...8356#post88356 (Holley Sniper EFI Fuel Pressure Tester/Gauge)
    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.

  3. #3

    Default

    I haven't driven the car other than to move it in the driveway so answer to question #1 is no, not Learning yet.
    Dead headed fuel pressure is high at the inlet. I've ordered a fitting to put a gauge on it to verify the regulator works, but I suspect it will be OK.
    IAC was about 5% at hot idle when it worked a few months ago, but I'm not going to let the engine get to temp now with such a lean condition. The IAC is not moving toward zero so something is telling it to stay open.
    No exhaust leaks. WBO2 is on the collector of the header and everything is tight.
    Don't know how to check if WBO2 has failed. I have not found a sensor input to verify it's putting out a signal. (Shouldn't there be a default if it failed?)
    No idea what this means or why it's relevant, "The Holley Sniper EFI will intermittently inhibit Closed Loop at idle, if the AE vs TPS/MAP RoC Blanking values are set too low."

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,701

    Default

    https://www.youtube.com/watch?v=rmnxKLjM25g (Wideband O2 Sensor Test/Diagnosis - it works!)
    If testing the WBO2 sensor key-on/engine-off, the sensor heater will time out, so you'll need to work fast.
    If you need more time, the WBO2 sensor test can be performed with the engine running in 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 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. #5

    Default

    Does the engine run okay Open Loop? It should run okay as long as the fuel map hasn't been hosed up. You might need to zero out the Learn Table.

  6. #6

    Default

    Quote Originally Posted by Danny Cabral View Post
    https://www.youtube.com/watch?v=rmnxKLjM25g (Wideband O2 Sensor Test/Diagnosis - it works!)
    If testing the WBO2 sensor key-on/engine-off, the sensor heater will time out, so you'll need to work fast.
    If you need more time, the WBO2 sensor test can be performed with the engine running in Open Loop mode.
    I'll give it a shot, thanks!

  7. #7

    Default

    It seems to run better in Open Loop now that I understand what it means. I did not realize that the WBO2 sensor was removed in Open Loop. The IAC was closing down and the RPM stabilized. Datalog attached. Looks like the WBO2 sensor failed? Maybe why it never gets out of "Init..." in the handheld?

    On a side note, my handheld reads AFR = "init..." with key on and WBO2 still installed. I assume it would read the same if I pulled it out, making it impossible to do the YouTube test.

    Progressive TBI Enable/Disable. This shows up on the handheld tuning section and I don't know if I need to set a value for it. The manual says it's not available with the 4 injector Sniper kit, yet I have it on my handheld. No explanation of what it does though.
    Attached Files Attached Files

  8. #8
    Join Date
    Oct 2016
    Location
    Albuquerque, NM
    Posts
    110

    Default

    Quote Originally Posted by ny67stang View Post
    Progressive TBI Enable/Disable. This shows up on the handheld tuning section and I don't know if I need to set a value for it. The manual says it's not available with the 4 injector Sniper kit, yet I have it on my handheld. No explanation of what it does though.
    https://www.efisystempro.com/sniper/...ve-linkage-kit
    &
    https://forums.holley.com/showthread...ssive+throttle
    1968 Camaro, 383 with Dart Pro 1 aluminum heads and Comp Cams roller cam, Holley Sniper EFI with Dual Sync distributor, Muncie M21 4-speed transmission, 3.73 12-bolt Eaton posi differential.

  9. #9

  10. #10

    Default

    Received the fittings and gauge (Earl 1-100 psi) to check fuel pressure. Static pressure (Key on/engine off) 50 psi. Running pressure 66 psi. 3/8" fuel lines, in-tank pump. The only bend is a slight bend to get to the tank to from the frame rails into a 90° fitting on the tank. I know this is higher than recommended, so I have a call into Holley support to see if this in the acceptable range. Also, should the fuel tank be pressurizing?

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