My Challenger is acting up. It runs rough on moderate acceleration and sometimes pings under moderate load like one or more cylinders are advanced too much. It has the MP black "vibration proof" 6 analog box.

I'm getting ready to check it all out and wondered if these are symptoms of a faulty ignition box.

The box is triggered by the "points" wire from an XFI box.

I wouldn't think so.

When my last 6a died it died dead no whimpers first. Did you check for fouled plugs?

I'll pull the plugs, inspect cap/rotor/wires and double check timing tommorrw. I've had worn ignition parts cause a miss, but never random pinging. That's what made me wonder about the box.

As the MSD 6 responds to the trigger with a spark it is hard to see how a faulty one conld make a spark before the trigger event. It's not like late model engines that calculate the next spark based on crank position, at least that's my idea of how they work.
R.

Some good reading here about the MSD boxes..
http://classracer.com/classforum/showthread.php?t=37282

Mine recently died, and it took out the coil first. It was very intermitent and it took a long time to find it. I also had a slight miss over the summer I couldn't find, but suspected the box. I have never liked the MSD6 boxes. I had a previous one that I replaced with a 7AL, and what a difference. This last one I replaced the MSD6 with a Crane Hi-6, and, again, what a difference. Throttle response, the way the idle is better and cleaner, amazing.

Fixed... it was a loose plug wire. Its running like it should now.