MSD EFI Coil Problem!!! HELP!!!

Your stock ignition system is good to 400 HP unless you have NO2 or pressurized induction. Return the coil and use the refund money for some gauges or other small item.

my msd blaster coil in the 89 makes my factory tach jump up to 4k and it drops back down after bout 10 seconds.

Jrichker, are you saying that I don't really need my Accel 300+ ignition box? Doesn't having an ignition box put less stress on the TFI module because it doesn't have to fire the coil directly? Btw, my tach will jump around with it after 3000 or 3500 rpm, whatever the cut-in point is for the multiple sparks.

JR is right about the ignition. I think that folks with mild combos who say they noted a difference had some sort of tune-up or degraded stock ignition component to begin with (and a fresh set of NOS parts would have created the same restoration of power).

MSD might have some tech on their site about reducing noise in the system as well (you might have also noted a hum or blue hue around the coil at night).

For the box question, the TFI isnt creating the high voltage.

Yea you can definately stick with your stock ignition, its actually pretty good on the 5.0Ls. Like the other guys said, you can easily go to 400 horse with a stock ignition. When i got my first stang, it was an 89 Hatch LX 5.0, and i just did some small things at first, like put in an MSD Blaster coil like you did, and i had nothing but problems with it. THe outer housing actually cracked and i never new it, and i had a bad misfire for a while and couldnt figure out what it was cause the crack was like a hairline. I didnt notice until one night i had the hood open and i was adjusting the timing and i had my brother rev the car up, and it looked like lightning coming out of the coil housing! haha and the coil was only about 2 months old! I said F this, and i put the stock one back in and never had a problem. I also HEARD not to run an aftermarket coil with the stock distributor in a 5.0. hey good luck