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Thread: 5.0 idling at 800-1000, never been able to fix it

  1. #11
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    Quote Originally Posted by SlaughterDog View Post
    As far as the tach goes, I do have the digital tach, that is what I’m basing this on, and now I feel like a dummy for being concerned since I’ve always known that period Fords have inaccurate induction tachs; makes me wonder how that affects timing advance and other ECU functions.
    The EEC has an accurate reading of RPM, you don't need to worry about that. These cars don't have any kind of multiplexing, which means that the different electronic modules don't communicate with one another. The cluster and EEC both know the engine speed, but it's because they both pick it up independently. It's like vehicle speed; the cluster, the EEC and the cruise all know the vehicle speed, but it's because they're all tapped into the VSS. They're not sharing info.
    1988 Thunderbird 5.0
    GT40P, TFS-1, KB domes, 30#, MAF conversion, Explorer GT40 Upper/Lower, Smog delete, Wide Ratio AOD Mod, Unlocked Speedo, 3G Charging System Upgrade, Hi-Torque Mini Starter, 3.73 LSD, BBK 1 5/8 unequal headers, H-Pipe.

    88 Thunderbird/Cougar EVTM
    (Thanks to Trinom for hosting)

  2. #12
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    Quote Originally Posted by SlaughterDog View Post
    Only vacuum line I’ve replaced was the source line, but there appear to be no other leaks.

    As far as the tach goes, I do have the digital tach, that is what I’m basing this on, and now I feel like a dummy for being concerned since I’ve always known that period Fords have inaccurate induction tachs; makes me wonder how that affects timing advance and other ECU functions.

    If it’s reading high at low RPM, could it also be reading low at high RPM? When it reads 5k (all the redline bars from 5 to 6 light up at the same time) I let off the pedal to upshift, figuring the AOD is waiting too long. Waiting for the upshift at WOT feels like it’s left the power band and is slower.
    Yeah see here: http://www.foxtbirdcougarforums.com/...ght=tachometer

    It's pretty much useless.
    '88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, Edelbrock 70mm TB, 76mm C&L MAF, 30lb injectors, 2.5" exhaust, AOD with 2800 PI converter, 8.8 with 3.73 gears, 31 spline Traction-Lok, 31 spline Moser axles, 04 Cobra front arms, Maximum Motorsports extreme duty rear arms, subframes.
    '11 Focus, '12 Mustang 3.7, '17 Accord EX-L V6

  3. #13
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    What I'd like is for someone who knows electronics at an engineering level to look at it and find where pulse/rev is determined in the tach and to come up with a method to correct it for a V8. My research pretty much confirms what is in the linked thread, and that is that our V8 cars have a tach that is configured for a V6.
    1988 Thunderbird 5.0
    GT40P, TFS-1, KB domes, 30#, MAF conversion, Explorer GT40 Upper/Lower, Smog delete, Wide Ratio AOD Mod, Unlocked Speedo, 3G Charging System Upgrade, Hi-Torque Mini Starter, 3.73 LSD, BBK 1 5/8 unequal headers, H-Pipe.

    88 Thunderbird/Cougar EVTM
    (Thanks to Trinom for hosting)

  4. #14
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    Quote Originally Posted by TheFoeYouKnow View Post
    What I'd like is for someone who knows electronics at an engineering level to look at it and find where pulse/rev is determined in the tach and to come up with a method to correct it for a V8. My research pretty much confirms what is in the linked thread, and that is that our V8 cars have a tach that is configured for a V6.
    That would be the ideal. Then I could ditch the Autometer tach. Until then it stays.
    '88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, Edelbrock 70mm TB, 76mm C&L MAF, 30lb injectors, 2.5" exhaust, AOD with 2800 PI converter, 8.8 with 3.73 gears, 31 spline Traction-Lok, 31 spline Moser axles, 04 Cobra front arms, Maximum Motorsports extreme duty rear arms, subframes.
    '11 Focus, '12 Mustang 3.7, '17 Accord EX-L V6

  5. #15
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    There's always THIS.
    1988 Thunderbird 5.0
    GT40P, TFS-1, KB domes, 30#, MAF conversion, Explorer GT40 Upper/Lower, Smog delete, Wide Ratio AOD Mod, Unlocked Speedo, 3G Charging System Upgrade, Hi-Torque Mini Starter, 3.73 LSD, BBK 1 5/8 unequal headers, H-Pipe.

    88 Thunderbird/Cougar EVTM
    (Thanks to Trinom for hosting)

  6. #16
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    Quote Originally Posted by TheFoeYouKnow View Post
    There's always THIS.
    Well that looks like a cheap/easy enough fix. Power, ground, and splice into the tach signal to the factory tachometer. I might have to pick this thing up. Based on prior testing I'm *pretty sure* that the stock digital tachometer is set up for a V6, even in V8 applications.
    '88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, Edelbrock 70mm TB, 76mm C&L MAF, 30lb injectors, 2.5" exhaust, AOD with 2800 PI converter, 8.8 with 3.73 gears, 31 spline Traction-Lok, 31 spline Moser axles, 04 Cobra front arms, Maximum Motorsports extreme duty rear arms, subframes.
    '11 Focus, '12 Mustang 3.7, '17 Accord EX-L V6

  7. #17
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    Somebody has to go first. If it works out, I'm sure a lot of guys around here will get one, too.
    1988 Thunderbird 5.0
    GT40P, TFS-1, KB domes, 30#, MAF conversion, Explorer GT40 Upper/Lower, Smog delete, Wide Ratio AOD Mod, Unlocked Speedo, 3G Charging System Upgrade, Hi-Torque Mini Starter, 3.73 LSD, BBK 1 5/8 unequal headers, H-Pipe.

    88 Thunderbird/Cougar EVTM
    (Thanks to Trinom for hosting)

  8. #18
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    I'm going to try and pick it up over the summer and then run it and the Autometer tachometer at the same time to see how accurate it can make the stock digital tachometer.
    '88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, Edelbrock 70mm TB, 76mm C&L MAF, 30lb injectors, 2.5" exhaust, AOD with 2800 PI converter, 8.8 with 3.73 gears, 31 spline Traction-Lok, 31 spline Moser axles, 04 Cobra front arms, Maximum Motorsports extreme duty rear arms, subframes.
    '11 Focus, '12 Mustang 3.7, '17 Accord EX-L V6

  9. #19
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    I like that idea. Make a solid write-up of it. Pics, testing, the works.
    1988 Thunderbird 5.0
    GT40P, TFS-1, KB domes, 30#, MAF conversion, Explorer GT40 Upper/Lower, Smog delete, Wide Ratio AOD Mod, Unlocked Speedo, 3G Charging System Upgrade, Hi-Torque Mini Starter, 3.73 LSD, BBK 1 5/8 unequal headers, H-Pipe.

    88 Thunderbird/Cougar EVTM
    (Thanks to Trinom for hosting)

  10. #20
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    I dunno, $89 plus tax and shipping plus the install, that's nearly 1/4 the value of the car.
    Quote Originally Posted by jcassity
    I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
    Hooligans!
    1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
    1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
    1986 cougar.
    lilsammywasapunkrocker@yahoo.com

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