Megasquirt 2 HEI tach input
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- MS/Extra Newbie
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Megasquirt 2 HEI tach input
New ms2 having issue with rpm jumping. Have HEI mod with opto tied to 5 volts with 390 ohm resistor. RPM jumps from 1000 to 2500-6000.
I have scope of tach input and output of Opto to MIcro. Looks like it not switch correctly. This is not a GM module it a aftermarket module. Could this be the reason that the signal has a lot of noise. I am using a shielded cable to Tach signal. Set for falling edge.
I have scope of tach input and output of Opto to MIcro. Looks like it not switch correctly. This is not a GM module it a aftermarket module. Could this be the reason that the signal has a lot of noise. I am using a shielded cable to Tach signal. Set for falling edge.
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- Super MS/Extra'er
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Re: Megasquirt 2 HEI tach input
Is this a computer controlled HEI module, or are you triggering off the coil negative?
Matt Cramer -1966 Dodge Dart slant six running on MS3X
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Re: Megasquirt 2 HEI tach input
Triggering of of GM HEI tach signal . Its mechanical/vaccum unit. So I am not controling the ignition, that the next step after I get fuel only working good.
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- Super MS/Extra'er
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Re: Megasquirt 2 HEI tach input
Don't use the HEI mod for this - it is only for the computer controlled HEI. Instead, set it up for coil negative triggering.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
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Re: Megasquirt 2 HEI tach input
I am using a 8 pin gm hei module. Coming off the tach output. So it would be best to go of the negative coil instead with hardware set up for coil?
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- Super MS/Extra'er
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Re: Megasquirt 2 HEI tach input
By the tach output, do you mean the wire that drove the factory tach (which connects to the coil negative) or the "R" pin of the module?
Matt Cramer -1966 Dodge Dart slant six running on MS3X
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- MS/Extra Newbie
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Re: Megasquirt 2 HEI tach input
Factory tach output.
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- Super MS/Extra'er
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Re: Megasquirt 2 HEI tach input
Use the R pin instead.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
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- MS/Extra Newbie
- Posts: 5
- Joined: Tue Apr 28, 2015 3:43 pm
Re: Megasquirt 2 HEI tach input
Switch to neg coil. Set up board for coil input. Megasquirt
operating great now.
operating great now.