Well a few weeks ago I disconnected my Crane Ign. Box due to a "Intermittent, High RPM, Miss-fire" It seemingly went away, but a few days later, or the fact that I got harder on the car it would missfire. It would either blip, or flat out freak out.... ugghhh

Well in the crane book, it had mentioned a faulty coil in the trouble shooting section. So i got to thinking.

I never had this issue until the box went on the car.

When I did the job I removed my MSD coil (1yr old) and put in the crane one that came with the box. Then I had the problems.

Now i would rather start at the cheapest point and work my way back, since i had the coil i would swap them.

My crane coil was loose on the bracket, that could have been a problem.

I also noticed that I have 2 ground straps that go to my coil bracket. 1 is for the Chassis, its a braided strap, the other is from the wiring harness where the ICM and ignition coil wires come out of. I also noticed how they were not attached to the cyl head directly.

On the head there is a 14mm stud bolt on to which the coil sits on and another 14 mm nut sandwhiches the coil on.... so I get to thinking. Thats not a good ground. It could have interference.

So I take my coil bracket off and clean her up, and put the MSD back in there and make sure its real tight. I take some brake clean and clean the front surface of my cylinder head. Its nice and shiney, i do the same to the stud bolt. Then I go a little further and take some sand paper and scuff lightly right where the stud will screw into.

Then I scuff both ground strap and brake clean them off.

I sandwich the straps to the cylinder head and then put the stud bolt in and make sure its tight. Then I put the coil back on and put the car back together.

So far I only drove it a day and got real hard on the car 5-6 times and i couldnt get it to freak out. I have to drive it some more but aside from that it runs fine and stronger.

As it stands, no codes have been thrown, and i have replaced everything except the ICM modual. So if it doesnt freak out, i will put the box back on and let everyone know how it went.
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'94 Black Z28, 383 LT1 Breaking 11's SOON!

 

I figured this would help anyone who has had this issue with their ignition boxes, from accel, msd, and crane.

 

Its always nice to figure out a problem isnt it

 

I had similar problems with a intermittent high rpm miss. Was definatly my coil, replaced the aftermarket one with a proper gm coil.
Should have never cheaped out on that aftermarket one in the first place