Tach signal input

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archy355
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Tach signal input

Post by archy355 »

Computer: MS1 3.0 with mallory ignition box

Ive been scratching my head for a while now trying to get a smooth tach signal. ive tried quite a few things and i just cant seem to figure it out. currently i have the board set up as described here: http://www.megamanual.com/ms2/V3assemble.htm#input for a hall/optical input. currently the ms1 is only controlling fuel. i have the tach signal from my mallory box going into the ms1 via the white wire i believe its pin 25. the truck runs great but when i look at the data log the ms is not seeing a smooth tach signal at all. i have attached my data log.

I do have a 60-2 wheel on the motor with one of diyautotune hall sensors, i have it going through the vr circuit but i was having the same type of problem so i disconected it and built the hall circuit to try running the box for ignition. i would love to run the trigger wheel and have complete control over the ignition. i see there are multiple ways to build the hall circuit, which way would be best with the sensor.

thank you in advance for anyhelp.
slow_hemi6
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Location: Australia

Re: Tach signal input

Post by slow_hemi6 »

White wire is normally a points input for a mallory ignition. Yellow is the tach out. This wire produces a 12 volts square wave
signal with a 20% duty cycle. What model Mallory is it?
Find the Manuals up top under Quick links: Manuals. :RTFM:
Cheers Luke
archy355
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Re: Tach signal input

Post by archy355 »

mallory hyfire 658.
slow_hemi6
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Re: Tach signal input

Post by slow_hemi6 »

Read this in the instructions.
Tachometer Operation:
If a tachometer is used, connect tachometer ignition sensing lead to the TACH terminal on the
HYFIRE®VI Electronic Ignition Control.
If the tachometer does not work after being connected to the TACH terminal, connect the
tachometer ignition sensing lead to the GREEN WIRE from the Ignition Control Harness.
http://prestoliteperformance.com/media/ ... 5_6851.pdf
Find the Manuals up top under Quick links: Manuals. :RTFM:
Cheers Luke
DaveEFI
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Re: Tach signal input

Post by DaveEFI »

It's one of those things that a 'scope is so useful for. You can look at what the input signal at Tach Select looks like and more important the output from the VR conditioner to the processor at Tsel.
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archy355
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Posts: 55
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Re: Tach signal input

Post by archy355 »

slow_hemi6 wrote:Read this in the instructions.
Tachometer Operation:
If a tachometer is used, connect tachometer ignition sensing lead to the TACH terminal on the
HYFIRE®VI Electronic Ignition Control.
If the tachometer does not work after being connected to the TACH terminal, connect the
tachometer ignition sensing lead to the GREEN WIRE from the Ignition Control Harness.
http://prestoliteperformance.com/media/ ... 5_6851.pdf
i like this idea ill give that a whirl. if that doesnt work the msextra manual descibes a different way to build the circuit. the have a circuit for a low to high sensor so ill build that circuit and give it a try.
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