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Tach questions in a fox stang

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Old May 8, 2010 | 04:28 PM
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Default Tach questions in a fox stang

Was wondering how to get a tach signal to the stock gage.
I thought just hooking up the output from the computer to the line going into the stock gage would work since the car was originally a 4 cylinder no dice.
Is there a converter box people use?
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Old May 8, 2010 | 04:47 PM
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What year is the car? For my 01 Mustang the computer tuner said he can modify the tach signal from the chevy ecm to what the ford tach needs.
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Old May 8, 2010 | 05:18 PM
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Car was an 85 lx 4 banger.
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Old May 8, 2010 | 08:08 PM
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You can check with Dakota Digital, they have all kinds of magical black boxes.
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Old May 8, 2010 | 08:31 PM
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Originally Posted by 99MUSTANG5.3L
What year is the car? For my 01 Mustang the computer tuner said he can modify the tach signal from the chevy ecm to what the ford tach needs.
oh really, any idea what he changed? I just built my wiring harness yesturday and I am getting ready to drop the engine in my 1998 GT. thanks!

-Garrett

did he use HPtuners? do you have a copy of the file?
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Old May 8, 2010 | 08:50 PM
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In HPT there is a way to modify the signal count so it will work with a 4, 6 or 8 cyl tach but I'm not aware of any other differences. I'm running a Dakota Digital box because I didn't know this before I bought it. My tach always worked fine but wasn't accurate (former V6 car) so I installed the box since I didn't have access to HPT.

I have heard of some people needing a resister in the path to get the reading to steady out or read at all but I don't remember all the details of why. Read here for what I am talking about and give it a go. Hopefully it works for you.

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Old May 8, 2010 | 08:59 PM
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Originally Posted by ge_forcez22
oh really, any idea what he changed? I just built my wiring harness yesturday and I am getting ready to drop the engine in my 1998 GT. thanks!

-Garrett

did he use HPtuners? do you have a copy of the file?
No I don't know what he changes or what he uses to program to ecm. I've talked to a couple of tuners and they have all said that this is no problem. I'm currently in the assembly stage myself right now and do not have the car even close to running right now, just doing research(like everyone else) to hopefully have things go as smooth as possible!
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Old May 9, 2010 | 08:56 AM
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ive used a dakota digital box to get the right tach signal on a project and it worked perfect.
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Old May 10, 2010 | 02:34 AM
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I used a 4 cyl tach.. but it was for a 93. All i did was connect the tach wire to the ecu tach signal wire.. You might try swaping out to a different cluster?
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Old May 11, 2010 | 07:35 PM
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Originally Posted by gofastwclass
In HPT there is a way to modify the signal count so it will work with a 4, 6 or 8 cyl tach but I'm not aware of any other differences. I'm running a Dakota Digital box because I didn't know this before I bought it. My tach always worked fine but wasn't accurate (former V6 car) so I installed the box since I didn't have access to HPT.

I have heard of some people needing a resister in the path to get the reading to steady out or read at all but I don't remember all the details of why. Read here for what I am talking about and give it a go. Hopefully it works for you.

This worked thank you
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Old May 11, 2010 | 08:36 PM
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Rule of thumb for tachs

Wrong speed on the gauge, reset the PCM output via tune or converter box
No tach at all, booster wire
No tach with booster wire, bad tach/cluster
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