Ok, I need some suggestions concerning my multiple ignition module failures.

The car is a 1984 Firebird with the 305. I've switched it to a regular Edelbrock carb and an Accel HEI distributor.

It runs great (at least for a while). All was well after the parts swap and the regular carb and distributor operate without a hitch. I stored it in a friend's barn under cover last winter. This spring I pulled it out and it started right up. About 5 miles down the road the ignition module died.

I had it towed home, installed a new module and life was good. That is until today. I've driven it a few times since the new module install (most of the time it's in my garage and I'm working on it little by litte). The new module worked flawlessly this summer. Now, today I took it out for a spin and it died on the highway. Another tow bill... yeah!

I brought it home and whipped in another module and it fired right up. I'm cleaning the mounting area for the module and making sure there is silicone grease under it for heat transfer. All the connections are good and it still fried itself.

I am stumped on this one. Anyone have any idea as to why the modules blow like this? I would appreciate any insights you care to share. Thanks in advance.

I am wondering if getting rid of the module and going with an MSD 6A box would solve this problem once and for all. Anyone think that's a good idea?

Brad- the king of tow trucks

 

Surely throwing $600 at a problem will solve it but it doesnt have to be done.

What modules are you using? i believe if they do not have the dwell control circuit they can die out pretty fast.

Is their lots of moisture in your area? maybe the connections are shorting out.


Ahhh the joys of running a computer controlled rig, Glad the closest thing to a computer in my car is the cd player!

 

The modules usually shut-down because they overheat, or are subjected to excessive heat. But they ususally cool-down and the car will start after sitting for 20 minutes or so. Are you telling me the modules blew to the point that the car was not startable at all after it shut off?

 

I am using the standard replacement modules from Jegs (their own brand). Even the regular module that came with the distributor from Accel didn't last long.

As far as moisture, no my garage is high and dry at all times.

In reality, there is no computer on this thing at all. I removed all of that and switched to a regular HEI with no computer controls. The only electronic part of the ignition is just the module itself. Unless you are running a points type distributor, you likely have one of these too.

The MSD box won't run anywhere near $600. I was actually thinking of getting one anyway as you have to remove the ignition module from the distributor and just use the magnetic pickup that hooks directly to the MSD box.

Thanks for the reply. Anyone else care to hazard a guess?

 

MSD won't solve your problem...

Again, are your modules TOTALLY wiping out, or are they just acting as if theyve overheated?


You arent running any kind of race coil or anything are you?

 

i read some were on this forum that one guy blew 6 icm and found out his alt. was over amping and causing the failures
check alt. voltage out put

 

Damn good idea, I'd forgotten about that....I wanna say that was Karl? (KED)

 

yes your right from v-6 forum

 

Thanks for the replies guys. I appreciate it. I took the module I just pulled to Autozone. They hooked it up to their whiz-bang module checker and it is absolutely and totally dead. It's not just an overheating issue.

I am starting to wonder if the alternator may just be the problem. Everything else in the circuit is brand new except the 12 volt line that feeds the distributor and the tach line.

I got home late tonight. I'll check the output voltage from the alternator tomorrow night and report back. I do remember checking the voltmeter about 2 miles or so before the car shut down. It was at about 13.5 volts. It may be that the voltage regulator has an intermittent fault that is causing a voltage spike. This is entirely possible. The alternator is ancient and I was going to replace it anyway when I did the engine swap next spring or summer. It may be a good idea to swap it now as insurance against potential problems.

Oh, Nixon-- I am just running the Jeg's HEI replacement performace coil on this beast. Much like the MSD HEI replacement coil. Nothing really special, just a bit hotter than stock.

Again, thanks for the replies.
Brad

 

Ok, I fired the beast up and checked the alternator output. At an idle speed higher than normal (it was warming up and the choke was still on slightly) the voltage was 14.65 volts. This appears to be within the correct upper range for this vehicle. I was expecting something on the order of 16+ with my suspicions. It still could be an intermittent fault with the voltage regulator.

I am pulling the alternator and having it checked at AutoZone just to be absolutely sure.

I am also standing back from the situation and thinking about the distributor setup. This thing has a radio frequency interference capacitor attached to the module. If that thing had any internal breakdown, it would short the module to ground and kill it. I am wondering if I could have some kind of temperature senstive issue with this capacitor that could cause/contribute to this problem. Everything else is new, clean, well grounded, etc.

I am seriously thinking of replacing the alternator just to be on the safe side and the MSD route still intrigues me.

I talked with several gearheads today including some professional mechanics who are stumped as to why this is happening. The mystery continues....

 

I just skimmed through so someone may have metioned this, but a bad coil will cause ignition module failures. If the coil has an intermitent short it will over heat the module.

 

Thanks for the reply Todd. The coil is new as well, but that doesn't mean that it can't be at fault. I will check it or perhaps replace it just to be sure.

I took the alternator into AutoZone today. It checked out ok. We did find a small amount of bearing play and some noise in the bearings as well as a slight wobble in the pulley and shaft. I decided that it was time to retire it and will be picking up a new one tomorrow. Preventative maintenance is what I'm calling it right now. It looks horrible since it is so old that I would have replaced it with a new one next year when the new engine goes in anyway. I have also decided to go the MSD route as well as the units are on sale right now and the price is right. It will eliminate the module completely and in a discussion with MSD it will handle much higher voltages without so much as a hiccup. We shall see how it goes. Hopefully this will cure the problem once and for all. I'll keep everyone posted.

 

I'm assuming this is the large cap HEI being that you've removed the computer. Make sure that the ground strap inside the distributor cap is still there. It's a flat metal piece that hooks onto the coil and plugs in between the other 2 wires in the cap. Alot of these go missing when people change their distributor caps. Modules won't last as long without it.

 

Thanks for the reminder chevymad. The ground strap is indeed in there. That was one thing that would certainly kill it in short order. It is most perplexing that we could kill two modules in short order with all new components. My best guess is that the antique alternator has some kind of intermittent voltage issue and is causing a spike that kills the modules. Nothing else seems to make any sense at all. Thanks for the reply and reminder. I will double check it tomorrow, but I made a point to transfer the ground strap when I changed out the coil. Who knows, maybe I have gremlins?

 

Well, it has been forever since I posted on this problem. Sorry that I didn't report back on this. I ended up replacing the alternator (no more wobble to the pulley!) and a good steady voltage output.

I also went ahead and swapped in an MSD6A box. The car starts up much quicker, idles better and no problems with blown ignition modules. I am a happy camper on this one.

Thanks to all who replied and helped out. I really appreciate the folks on this forum and their helpful advice.

Brad, the ex-king of tow trucks!

 

I Have an 89 gta 350 tpi and I got my ign mod replaced in march. yup, thanksgiving weekend, it wouldnt start cause of the cold weather n needed a jump 2 start. well sunday it wouldnt at all and used spark tester. no spark. so im wondering theres a junk yard near town, what should i look 4 at junk cars cause there r no camaros or birds with v8s in them. any truck er something?