I just upgraded my ignition system to MSD Street fire. I got the ignition coil, MSD cap and rotor and MSD street fire plugs. Also got NGK IS Iridium plugs. Put everything in and it runs but will die under load. Don't get it. I'm gonna check the wires. When it start the tach will flicker intermittently. And ideas?

 

Okay so I put stock ignition coil back in it and it runs fine. Why isn't the MSD coil working. Or do I have to reprogram ECM

 

It's not uncommon to get a aftermarket coil bad out of the box. The unfortunate problem is, most place won't accept electronic parts back if the package has been opened. There is no programming needed for a coil change. One thing to try is where the bracket bolts to the coil, scratch up the coil where the little bolts go through on the coil and the bracket to get a good ground.

 

Well I got a street fire coil and an MSD HEI coil. But maybe ur onto something with the ground. Thanx with troubleshoot

 

Guarantee the factory parts were an order of magnitude higher quality than most anything you'll find at the corner auto parts store now. "Street Fire" is MSD's economy line, kind of MSD in name only. Pretty sure that when you asked for advice a couple weeks ago, I told you not to waste your money on that crap. Oh well, if it runs better with the old stuff, switch it back.

Double check your firing order and connections. Easy enough to make a small mistake. That said, if it runs better after only switching the coil back, run the original coil.