Before I get into details, I have an MSD 6AL box, blaster coil, and pro billt distributer.


Before today, the camaro had a problem starting up(for the last month). I always thought it was pouring in too much fuel. But after today, I disagree. I'm drivin home from college and the car starts studdering and dies(20min into the trip). I sat on the side of the road trying to crank her over for about 10min. I got her started and went on my way. Every stop light the same problem re-occured as the last. another 15miles down the road and it cut out again. It first started tring to die/stall. When I gave it gas, I had backfires with the sound intesity of a rocket launcher. So I rolled her across the street into a body shop and charged the battery because it was getting low from cranking. I hooked up my spark tester and was getting no spark. After figiting with everythingfor about 2hrs, I got spark and tried continuing on my merry way. It was not runing well at all!

I made it 2hrs to my friends house and again the car cut out with the very bad backfiring. While I had no spark, I checked the coil. Positive side of coil had no power. I tried wiggling every wire, checked every fuse, connector, EVERYTHING and no luck. So I called a flat bad. Figures it starts up and has spark when he gets there. But it dies out randomly. It could be 5min or it could be 1hr. The driver said somethign about the resistor in the msd box causing problems... I need some help guys because I'm getting lost.

PS: power and ground to msd box are good.

 

You can't directly chekc power to the + side of the coil with an MSD box installed. It doesn't work the coil like a stock system does at all. It gives it a massive 400V shot of juice at the exact moment it want to fire the coil. That's the difference between a capacitive discharge ignition system and a typical kettering inductive ignition system that charges the coil with 12V constantly and then breaks the voltage at the moment it wants to fire the coil.

I have only run into ONE situation similar to yours where it was NOT the MSD box itself. In that case it was the coil that went bad internally. When it got hot, typically after a WOT run the engine would shut off. Sit by the side of the road for 15 minutes and it would again fire up just like nothing was wrong with it. After pulling out hair out changing everything in the ignition system I temporarily swapped in a known-good stock coil...... magically, it ran perfectly after that.

The only other thing it could have been, potentially, was a bad pickup in the distributor which could also exhibit similar symptoms.

Weirdo problems that only happen when stuff gets hot are almost always a bad electronic part. Heat is the enemy of electronic parts.

 

I'll also add that having a complete, known-good HEI distrubutor laying around is a handy thing to have when diagnosing ignition problems (or ruling them out as the cause of a problem). Earlier in-cap HEIs it's like a complete "ignition in a box"- completely self-contained. But even later computer controlled divorced-coil HEIs really only have 3 parts- the distributor, the coil and the 2-wire connector that runs between them. Everything else is just plugging into the stock wiring harness connectors.

 

Thanks some helpfull information Damon. I didn't know that about the msd boxes. I wonder If I could see it with a scope. I usually check the permanent magnt sensors in the distributor with a scope and look for the saw pattern but I don't have access to one now.

What are the specs for checking the primary/secondary coil's resistance? Maybe I'll try that before buying a new one.

I'll check the perm magnet sensor tomorrow just to make sure.
Last resort - I'll bypass the 6AL box and run the power and switching ground wires right to the coil