MSD blaster coil and misfire

[kamesama980]

I figured while I had the engine apart doing gaskets I'd try the MSD blaster coil that I've heard good things about.... got it back together and went for a drive and now there's a bad miss over 2500 when it's warmed up (misses down to 1200 when cold) this is no-load and all gears, all throttle levels, and ignition based cause the tach goes whacky when it happens (aftermarket tach). then I got the idea to swap the old coil back in and viola, runs perfect (relatively speaking)

it's the MSD 'GM external coil" from autozone that bolts up and plugs in.

so... WTF? any ideas? suggestions? return it, exchange it for a new one, or do something to make it work?

[92 s10 project]

Being that you can swap in the original and its ok, I say the coil is at fault. Id swap it for a new one. If that messes up too I guess get your money back or try a different brand like the one from Accel.

[Steady Eddie]

Try disconnecting the tach---just to see if it is dragging the output voltage down...

[CFM-Z440]

I just bolted the same coil in today and I corrected a problem with mine


Im wondering about the condition of your coil wire and plug wires. The MSD puts more load on the wires, and will arc far more easily.

[kamesama980]

the whole ignition system is new as of this spring and still perfectly clean and all that. the guys at MSD got back to me with a very nice and concice "sounds like you got a bad coil" so I'll exchange it sometime soon

[kamesama980]

got the new coil in and it runs better than ever. most obvious gains seem to be in the 2500+ range (like passing without downshifting) though there was no noticeable misfiring with the stock coil up to 6k.

[neo71665]

Make sure the bolts holding it all on are tight. When I done the same thing to my 2.8 I had some of the bolts come loose and it seemed like it was arcing and running like crap. I don't know if the coil grounds are the bolts or what but tightening them up seemed to fix it on mine.