Using 2 step with a ProMag...

Has anyone used a Playback AutoMeter tach with a mag?

Im running a SBC with a Promag 12LT using a two step to control the launch.
Using my Auto Meter playback tach, the launch chips are all 700-800 rpm off. The shift is accurate to the chip that it has, the idle is accurate but the launch chip is way off.

I have used four different chips and they are all off the same amount.

Any ideas?

I have read online that the Tach converter MSD#8132 has loses signal when on the two step and causes the tach to bounce but i dont think this is the same thing...its bouncing some but the bounce is still 700 RPM off the desired limit...Im assuming that running a battery should effect the bounce as well instead of using the generator.

I have sent emails to AutoMeter and MSD tech but nothing back yet.

 

This is where my confusion starts. I would think that since i have a onboard battery that the tach or converter should not shut down as there is a constant 12V to them. The tech article said it would bounce some but we are losing 700-800 RPM.

 

This is with the 4800 chip.

[video]https://youtu.be/uAxOwIzpi7Y[/video]

 

the tach and the convertor are not shutting down. The tach is seeing less pulses because the two step is shutting down cylinders. thats why your tach reads less rpm.