Triggering fuel only ms with tach signal?

[Jonwes]

Would this work? Im using a MSD 6al box, with the V2.2 board ms1, id rather not use a conditioner for the CAS signal, and I believe the 6al will work as is, without one, however ms wont. Since the 6al has a 12v square wave tach signal output already built in, can I use this?

Any and all help is greatly appreciated, ive searched multiple times, but still cant seem to find a way to do this without buying more stuff, making everything alot more complicated than it already is.....

[Rex4Life]

Yes it will. I've done it for a 2nd gen Rx-7 running off the tach signal. I did use a v3.0 board but I presume you could also use a 2.0

[Jonwes]

ya the 3 board already has the conditioner on it, so i dont believe i'd need to go this route in the first place. anyhow, awesome it works, may i ask how it was setup? like what sensor type you choose in the software?

thanks!
Jon

[Jonwes]

Hrmm, found the wiring diagram for the original megasquirt, which is what i need to use, BUT, i modified my ms to use the led 17 for spark output back in the day when i was using EDIS. im obviously no longer using EDIS. Do i have to change my board back to the way it was before edis? I still want to keep the software so i can get the 12x12 fuel table.

Thanks!
Jon

[newtyres1]

If the car is already running you could jumper the tach out into the opto in, supply power and ground to your MS (without it controlling anything or having any inputs connected) and connect up to MegaTune to check the rpm signal. Make sure the tacho in the car still works too.

Ian.

[Jonwes]

not already running