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  1. #1
    FEP User 1985gtauto's Avatar
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    Default cant find replacement 4 wire o2

    does anyone know where i could find a 4 wire o2 ensor for my 85 gt 5.0 cfi aod. po had spliced in a 3 wire but it doesnt work and cant find anyone that has a factory fit 4 wire.
    85 gt cfi aod daily driver
    96 crystal white cobra sold
    89 5.0 5spd coupe rip taken out by hit and run driver

  2. #2
    FEP Senior Member xpkpremier's Avatar
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    Default

    Ron Francis Wiring call him and he should be able to make you one, I got one from them and was a great fit. Mine was for an 86. I dont see why they cant make a 4 wire. good luck.
    Have:1986 Mustang GT Silver on Red, 5.0, 5 Speed
    1985 Mustang LX Red on Red 2.3 auto The Turd!
    Had: 1990 Thunderbird SC Red on Black 3.8 SC 5 Speed
    1969 Olds Cutlass S 350 Rocket auto, 12.5 Qt. Mile.
    1970 Chevelle SS 396 375 hp First car
    1977 & 79 Camaro Z/28 400 SBC auto
    1985 Camaro IROC Z Stock 5.0 auto
    1987 Camaro IROC Z Stock 5.7 auto
    1983 Olds Cutlass 350 Rocket auto 13.8 Qt. Mile
    1985 Mustang GT Black on Gray, 5.0, 5 Speed R.I.P.

  3. #3

    Default

    Maybe because the '85s don't use a 4-wire sensor? The late '85 CFIs use a 3-wire sensor,
    with a 4-position plug. There is a short adapter harness between the main sensor harness
    and the O2 sensor. That harness has 4 wires at the sensor harness end, with one of the
    wires grounding to the back of the passenger side cylinder head. The other 3 wires pass
    through to the O2 sensor connector.

    When I recently replaced the O2 sensor on my '85 Vert, I used the NGK 22014.
    Bosch number is 13913. Or Denso 2343001.
    Cheers,
    Jeff Cook

    '85 GT Hatch, 5-speed T-Top, Eibachs, Konis, & ARE 5-Spokes ... '85 GT Vert, CFI/AOD, all factory...
    '79 Fairmont StaWag, 5.0, 62K original miles ... '04 Azure Blue 40th Anny Mach 1, 37K original miles...
    2012 F150 S-Crew 4x4 5.0 "Blue Coyote"... 65 coupe, 289 auto, Pony interior ... '67 coupe 6-cyl 4-speed ...
    '68 Vert, Mexican block 307 4-speed... '71 Datsun 510 ...
    And a 1-of-328 Deep Blue Pearl 2003 Marauder 4.6 DOHC, J-Mod, 4.10s and Lidio tune

  4. #4
    FEP User 1985gtauto's Avatar
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    Default

    jacook the one we ordered and got was the bosch 13913. the plug end of it was the same as the end on the main harness but with only 3 wires. is there some kind of adapter harness that goes between the o2 and the main harness? i trying to get the cfi running right because i dont wanna change over to a carb on this car and any help would be greatly appreciated. thanks
    85 gt cfi aod daily driver
    96 crystal white cobra sold
    89 5.0 5spd coupe rip taken out by hit and run driver

  5. #5
    FEP User 1985gtauto's Avatar
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    Default

    bump
    85 gt cfi aod daily driver
    96 crystal white cobra sold
    89 5.0 5spd coupe rip taken out by hit and run driver

  6. #6

    Default

    Quote Originally Posted by 1985gtauto View Post
    jacook the one we ordered and got was the bosch 13913. the plug end of it was the same as the end on the main harness but with only 3 wires. is there some kind of adapter harness that goes between the o2 and the main harness?
    Well, yes.

    Quote Originally Posted by JACook View Post
    There is a short adapter harness between the main sensor harness and the O2 sensor.
    That harness has 4 wires at the sensor harness end, with one of the wires grounding to
    the back of the passenger side cylinder head. The other 3 wires pass through to the O2
    sensor connector.
    Cheers,
    Jeff Cook

    '85 GT Hatch, 5-speed T-Top, Eibachs, Konis, & ARE 5-Spokes ... '85 GT Vert, CFI/AOD, all factory...
    '79 Fairmont StaWag, 5.0, 62K original miles ... '04 Azure Blue 40th Anny Mach 1, 37K original miles...
    2012 F150 S-Crew 4x4 5.0 "Blue Coyote"... 65 coupe, 289 auto, Pony interior ... '67 coupe 6-cyl 4-speed ...
    '68 Vert, Mexican block 307 4-speed... '71 Datsun 510 ...
    And a 1-of-328 Deep Blue Pearl 2003 Marauder 4.6 DOHC, J-Mod, 4.10s and Lidio tune

  7. #7
    FEP User 1985gtauto's Avatar
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    Default

    any idea where i might be able to find one?
    85 gt cfi aod daily driver
    96 crystal white cobra sold
    89 5.0 5spd coupe rip taken out by hit and run driver

  8. #8
    FEP Senior Member
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    Default

    The three wire O2 is the correct one. It has 4 positions in the plug, yet only uses 3 wires. 1 is for heat, 1 is for ground, and one is for signal after the car goes into closed loop. It is the right sensor.

  9. #9

    Default

    You can build the adapter harness using a couple pigtails. Napa PN EC205. The grey/yellow,
    green/purple hash, and black/light green dot wires should feed straight through, as if you were
    plugging the O2 sensor directly into the main sensor harness.

    The fourth position on the sensor harness plug is an orange wire, and on the factory adapter
    harness, that wire gets grounded to the back of the right cylinder head, or to the large 1/2"
    -14 threaded boss on the back of the intake manifold, using a large diameter internal toothed
    ring terminal. It's basically the same style terminal that's used for the braided ground strap
    that goes between the engine and firewall.

    If you don't have access to that style of terminal, you can use a standard large ring terminal
    and add a star washer between the terminal and the cylinder head. You want to make sure
    whatever you use, the terminal gets a good bite. Grounds are really important.
    Cheers,
    Jeff Cook

    '85 GT Hatch, 5-speed T-Top, Eibachs, Konis, & ARE 5-Spokes ... '85 GT Vert, CFI/AOD, all factory...
    '79 Fairmont StaWag, 5.0, 62K original miles ... '04 Azure Blue 40th Anny Mach 1, 37K original miles...
    2012 F150 S-Crew 4x4 5.0 "Blue Coyote"... 65 coupe, 289 auto, Pony interior ... '67 coupe 6-cyl 4-speed ...
    '68 Vert, Mexican block 307 4-speed... '71 Datsun 510 ...
    And a 1-of-328 Deep Blue Pearl 2003 Marauder 4.6 DOHC, J-Mod, 4.10s and Lidio tune

  10. #10
    FEP User 1985gtauto's Avatar
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    Default

    thanks very much for telling me which wires go where. they originally cut the adapter and the o2 sensor ends off and butt spliced them together. but they didnt have the right colors and had the the orange one going through.
    85 gt cfi aod daily driver
    96 crystal white cobra sold
    89 5.0 5spd coupe rip taken out by hit and run driver

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