msd 8973 problem

As you probably know when you start the car it starts in the Run Retard Curve and the Time Retard Curve is active and when you hit the transbrake button the 8973 switches to the Launch Retard Curve and resets the Time Retard Curve to the "ready to lauch" mode. From what you are saying the 8973 failed to reset when the 12 volts was applied through the transbrake button prior to the run. I would try two things. First update the ProData software from the MSD site on your laptop, if you haven't already done so, and reload it on the 8973. Secondly I would check all the connections from the transbrake button to the blue wire on the 8973 and make sure all the connections are good.

I would have thought to control the launch that you would be using the Launch Retard function vice the Time Retard Curve or did I misunderstand what you were saying?.

 

The Time Retard Curve is not designed as a Launch Retard (In the Data Editor and NOT the Launch Retard Curve Graph). I think you would be happier on the Launch Retard. A big difference is the Launch Retard applies the retard when the transbrake button is held on and then releases it and ramps it back in when the button is realeased. The Time Curve does not apply the retard to the motor until the button is released. So with Time Retard Curve the motor is applying full power against your converter at stage and then suddenly lowers the power when the transbrake is released. I think you would get a smoother application of power by using the Launch Retard that pulls the power out at stage. It might be worth trying. You might make a difference to the initial hit on the rear wheels and maybe a smoother launch. It should also be easier on the converter. Using the Launch Retard would also stop what happened to you.