Here's the deal, I have a 89 IROC-Z L98 and I have the MSD digital 6 plus, I bought the MSD harness p/n 8876 for the GM dual connector stock coil. I hooked it up according to the harness installation instructions but when I fire my car up it runs like **HAMMERED ****** and my tach bounces around from 7,000 to 3500 RPM.

I've heard of the MSD boxes screwing with factory tachs but I've never heard of it making the car run like A$$ as well.
I unhooked the harness and plugged back in the stock Harness into the coil and the car runs fine.

What gives??

thanks,
Brian P
89 IROC-Z 355

 

Just wanted to push this back to the top

 

Is there an RPM pill installed in the MSD? Is it set up for a V6 or a V8? (You'll have to modify the wiring a bit if it's set up for a 6 but they usually come set for an 8). Is the MSD grounded well? And you might consider getting an MSD coil to match. Other than that, you may have a bad box..?

 

I'm considering getting the 6A box (not the digital one) but it's problems like this that I don't want to run into. I planned on getting the MSD coil with it too so I hope that would help. I'm interested to see what you decide to do Sena.



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1987 Camaro IROC-Z
350 TPI (L98), HyperTech Airfoil, K&N Filters and modified airboxes, modified MAF, AC Delco RapidFires, Taylor SpiroPro 8mm wires, Energy Suspension polyurethane bushings for LCA and sway bars, KYB struts and shocks, BFG g-Force Z-rated tires, STB, JET low temp stat, CarSound Hi-flow Cat, DynoMax 3" Mandrel-bent pipes, Flowmaster muffler, 3" chrome tailpipes, T-tops, and White exterior with red leather interior.

2001 Sunfire GT
Bone stock 2.4L, 5-speed, 200W Monsoon Sound System (8 speakers), Silver Metallic exterior with grey interior.

Web: http://www.angelfire.com/on3/whitelightening