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  1. #1
    FEP Power Member David Claflin's Avatar
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    Default Added Accel ignition, now tach won't work

    I took my Accel 300 ignition back from my son's 94GT, to use on my 86 coupe. Got it mounted, and hooked up easily, fired up and idled so much better, but tach doesn't work. Hooked up stock ignition, and tach works, is there something with aftermarket ignitions that adversely affect these old tachs?
    1985 LTD LX, Mach1 brakes, 17" Mopar police car wheels. 302, T5, 4.10s
    1984 LTD station wagon, with 84GT nose, some might remember it as the old Dugan Racing station wagon.
    1986 FHP coupe, stock shortblock, TW heads, Holley SMII intake, 4.88, T5Z
    1990 Red LX, ported AFR heads, TFS-R box upper, weenie cam, 1 3/4 long accufabs, 3" exhaust, T5, 4.56

  2. #2
    FEP Power Member 4-barrel Mike's Avatar
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    Default

    Needs an adapter. Check Summit, LMR, etc.

    Mike

  3. #3
    FEP Super Member xctasy's Avatar
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    Default

    Or you can find a 10k 1ohm pull-up resistor to do the job of making a nice 0 to 5 vokt square wave.

    See http://www.race-technology.com/forum...pic.php?t=3370

    Our old Cortinas had the same factory tach based on an American Yazaki patent. The switch from 4 to 6 cyl signal existed because there were 4 and 6 cylinder Fords...the electronic ignition for the EDIS or TFi needs no pull up because tge Tach is different.

  4. #4
    FEP Power Member David Claflin's Avatar
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    Appreciate it fellas, kind of odd how I originally had this on my 90LX, then when I got an MSD unit for that we put it on my son's 94GT, and on both cars the tach worked fine; now on this one it needs an adapter to work right.

    I found this on amazon, https://www.amazon.com/10K-ohm-Carbo.../dp/B007Z7MFDQ

    I see on this diagram there's already a 22K resistor from the coil to pin 4 of the ECU.
    http://www.veryuseful.com/mustang/te...ng-ECC-EFI.gif

    The only adapters I see on Summit are this type
    https://www.holley.com/products/acce.../parts/8910EIS
    1985 LTD LX, Mach1 brakes, 17" Mopar police car wheels. 302, T5, 4.10s
    1984 LTD station wagon, with 84GT nose, some might remember it as the old Dugan Racing station wagon.
    1986 FHP coupe, stock shortblock, TW heads, Holley SMII intake, 4.88, T5Z
    1990 Red LX, ported AFR heads, TFS-R box upper, weenie cam, 1 3/4 long accufabs, 3" exhaust, T5, 4.56

  5. #5
    FEP Power Member David Claflin's Avatar
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    Called Accell (Holley) techline today, told him what was going on. He asked when did I buy the unit, told him it's been on two different cars over the last 10-11 years or more. He put me on hold, then come back and said to look for a green wire in the rubber sleeve all the wires are in. So, pulled wires and found it, he said it should go to negative side of the coil. I tried it but no joy, that green wire has 12V on it when key is on, but it doesn't make the tach work. Wondering if that wire should have one of those pullup resistors
    1985 LTD LX, Mach1 brakes, 17" Mopar police car wheels. 302, T5, 4.10s
    1984 LTD station wagon, with 84GT nose, some might remember it as the old Dugan Racing station wagon.
    1986 FHP coupe, stock shortblock, TW heads, Holley SMII intake, 4.88, T5Z
    1990 Red LX, ported AFR heads, TFS-R box upper, weenie cam, 1 3/4 long accufabs, 3" exhaust, T5, 4.56

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