SCTA

What type of injection are you planning on going with? Bank to bank or SEFI? Without a cam sensor you can't run SEFI. I don't know if this has any relavance to your question, just something I noticed was not mentioned. I use a IPU trigger on both the crank and cam for mine. Although its not a MS, they all operate on the same principles.

engineermike

I think MS will only do bank-to-bank.

wannabess

Which tach output are you talking about, this one supplies "The Tach Output Terminal produces a 12 volt square wave signal with a 30° duty cycle."
Did you take the bypass filter out of your tach wire, it says you have to on GM tachs, or it wont work properly.

will62085

iTrader: (4)

yeah I've run a new wire directly from the MSD box straight to the back of the tach. That helped, but its still off

seank

The tach signal is the most important signal with MS or any other ECU. You want to directly piggy back off of a crank or cam sensor. The more hardware you add in the mix the less true the signal becomes. Maybe I miss understood what you were saying. I did a simple sketch below. Which one were you talking about doing.

Best
OPTI-<<<<<-Megasquirt

Best
Crank Trigger-<<<<-Megasquirt(OBD2 LT1 Only)

Have never tested this, but it might be acceptable
OPTI-<<<<<-Stock ECU-<<<<Megasquirt

Have never tested this, but it might be acceptable
OPTI-<<<<<-Stock ECU-<<<<-MSD-<<<<-Megaquirt


-sean