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Thread: AFR Reading Question

  1. #1

    Default AFR Reading Question

    My AFR screen is in the red. Shows a reading 34.5 AFR. Idle RPM shows 1320, then all of the sudden it will increase rapidly. Anyone out there have this problem. First startup.

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    20,186

    Default

    I'd check fuel pressure (LINK) & the WBO2 sensor (LINK). Ensure there are no exhaust leaks upstream of the WBO2 sensor. Is the fuel pump running on a consistent +12V?
    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/2500 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.

  3. #3

    Default

    With car running screen shows 12.6 volts. I had some loose header bolts coming off exhaust manifold. Retorqued header bolts and will check collector header bolts. Hope this does the trick.

    UPDATE: Restarted after checking bolts. Cold start AFR now stays around 13.5, Target AFR shows 13.3. Fuel Flow 12.6, cooling fans came on around 185° temp. Hot idle reads 850 RPM. Problem I have now is RPM will drop until it almost stalls then increases. It seems like it's sucking in air when wanting to stall. But I'm getting closer. Any info would help.

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    20,186

    Default

    Try opening the primary throttle blades (idle speed screw) a little more.
    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/2500 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.

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