My 86 has eaten ignition modules about every 6 months since I've owned the car (7 years). I carry a spare and have gotten to the place I can swap them out in about 15 minutes. It's a real pain when it happens and it is raining out.

It always happens after I've driven somewhere, shut it off and then try to restart, the motor just turns over but it won't start. Swap the IM and everything is happy again.

I've tried expensive ones and cheap ones and they all go out in about 6 months. Someone on this forum told me it was the pickup coil, so I swapped out to a new Accel distributor and they still blow out. I do have an MSD 6 AL and remote coil, other than that, the ignition system is stock.

I've heard that somebody builds an IM with a circuit breaker on it. If these things work I'd like to try one. Does anyone have any experience with them?

 

I've been Googling Ignition Modules and can't even find one with a circuit breaker.

 

Sounds like you have a shorted or a crimped wire somewhere. Do you have a Factory Service Manual?

 

I can't tell, are you using the stock big distributor cap? You may need to install a low resistance cap bushing. I was frying aftermarket HEI coils left and right until I installed one. I've not had any trouble using that with my MSD Digital 6+ either.

 

Yes, I have a FSM. What wire am I looking for?

 

I have the stock distributor cap that came with my Accel distributor. I don't have the coil in the cap, though. I have a remote MSD coil. But the coil hasn't been the issue. It's the Ignition Module that keeps burning out.

I've never heard of a "low resistance cap bushing." What is it and where does it mount on the cap? And, where do you get them?

 

I don't have my FSM handy to give you refrence, but any and all wires going to the ICM, the full length. It won't cost a thing and is where I would start looking.

 

Since this problem happened with two different distributors, I think I can assume that it may be one of the wires TO the distributor, not IN the distributor?

 

Here ya' go.

http://www.msdignition.com/dist_67.htm

 

I once heard that the coil and ignition module should be replaced at the same time as one will eat the other if they are not both in good condition. I'm not sure if that is true, just a rumor.

I had a Fiero with the MSD 6A box setup and I had the exact same problem. I could change the ignition module in 10 minutes and always had spare parts and tools for the job in the trunk. Hmm, has anyone else heard of these MSD setups causing this problem?

 

There's a short 3 or 4 wire harness that plugs into the dist., by short I mean it 8-10 inches long. A few years ago when I re-installed my dist. I crimped one of the wires under the dist. ended up getting a new one. I'd unplug both ends, check the connection-it's kinda hard to get to one end, the dist. side is easy, and I'd check the resistance on the whole 8-10 inch harness. Might be a good place to look.

 

Your MSD coil is frying your ignition module because the module was designed for the primary current and inductance value designed into the stock coil. The MSD coil exceeds either the primary current, inductance, or both. Put your stock coil back in and sleep at night!

 

I have been running an MSD 6AL with Accel cap & rotor , Accel Super coil for 3 yrs with no problems , stock module too . One thing I did was to run a dedicated ground wire from the dist to the engine. Also double check the short harness as reccommended earlier for a crimp or chafe. MSD coils are "different" from most others , they tend to confuse some ignition analyzers....don't know why but they do . Try a different coil for the next go and Good Luck !

 

I have a couple of questions for the OP - Did you use heatsink compound under the modules? Have you checked the little screens in the bottom of the distributor housing for obstructions?

 

sounds like you are frying the modules by not allowing the compound to draw out the heat because it's not there?
also, when you messed with putting the altered ignition together, did you by chance pull a wire out of the set timing connector?
that wire might be unplugged or loose or disconnected.
It has a quick disconnect, and is on the tan with black tracer wire

 

Yes, I always use the white grease at the bottom of the IM when I replace them. I haven't checked for any obstructions on any screens. How much do I need to take apart to get to them and what would obstructions do?

 

No, I'm putting the compound on the bottom of the IM.

I'll check for that wire when I get back to where the car is next week.

One problem I DID have was that the female plug of the short harness where it hooks in to the distibutor had to be modified to fit. Does anyone know where to get that short 8-10 inch harness to the distributor. I have a nagging suspicion that might be the problem.

 

The screens allow air movement - they are round about the size of a pencil erasurein the distr housing

 

I'm intrigued by the idea of running another ground wire, although it seems to me that the distributor body is pretty well grounded to the engine already. Do you think running the ground to the chassis might be more fruitful as this would tie the ground to the battery and chassis wiring better? Perhaps a huge honkin' ground strap from the engine to the frame might help?

 

there is the battery ground at the back of the left cylinder head. put your ground on that wire ground, it goes right to the battery.
I think more grounds, the better anyway, so add your ground.
But you know what? I'd go back to totally stock, and give that a try. if you don't blow a module, add the MSD unit. if then you ruin a module, i'd contact MSD and get their impression of what's wrong. it sounds like a capacitor that builds up some voltage, and when you turn the key, it zaps right into your module, blowing out a sensitive component.
There's also a possibility that the car ECM computer might have the same problem, can u borrow a computer to try? something is pumping more voltage into the modules than they need.
Just for grins, can u get to the computer, disconnect the computer connectors, and ohm the wires to the distributor connector.
d5 (EST bypass) the one that has the timing connector on it ---tan wire black tracer
d4 (timing control) the white wire on the plug
B3 (reference low) the black wire with the red tracer
B5 (distributor reference) the purple wire with the white tracer.
see if when you put an ohm meter from the computer plugs to the dstributor 4 wire plug, you get continuity.
DON"T try to ohm the distributor unless you got another module handy because you will blow it out using the battery in the meter.
if those are ok, I know there's a ground wire on the module or the module plate. go from the plate/ground to the battery negative cable.
if that's ok, return it back to stock and see what ensues.
Chris