Intermittent no spark from coil

[dpixel]

Hi guys.  I'm trying to track down a no start situation.  It's an intermittent problem.  It finally acted up when a friend was over and I had him crank the engine and realized there was no spark coming from the coil.  I replaced the coil and the same intermittent problem exists.  I have and orange ignition module.  Do these sometimes go bad? 

Thanks, Dave

[Ghoste]

They sure do.

[dpixel]

Is it a common problem?  And with the problem being intermittent, does that sound like it could be that?

[Ghoste]

It isn't uncommon that's for sure.  Typically they work or they don't but I have had issues with them in the past where it was intermittent.  Make absolutely certain that the unit is well grounded.

[elacruze]

It isn't uncommon that's for sure.  Typically they work or they don't but I have had issues with them in the past where it was intermittent.  Make absolutely certain that the unit is well grounded.

[Nacho-RT74]

I'm toward to module... MP units ( including Chromed, we though not but latelly they too ) are coming bad. APPERANTLY BAD GROUND inside printed circuit board. No matter how much good ground you make on exterior case, but IT LOOKS the problem is the solded point inside the box at a ground strap or something.

A friend of mine already fixed that on his orange box. Is working on make the fixment without mess with all the isolator stuff on back, just opening a hole there, reinforcing the solding point and seal it up again.

[dpixel]

Thanks for the feedback everyone!   

So either way it sounds like a bad ground if it's the module.  And can I assume the unit is grounded by the mounting bolts to the firewall? 
Also, can these fail for other reasons?

Any chance of a bad ballast resistor.  Can those go bad?

[Ghoste]

Ballast resistors can fail but you will usually find they show their symptoms as the engine firing during cranking but the second you release the key from the start position to the run position, it dies.

[dpixel]

Ok. I got home from work and tried to start it.  Nothing....just cranked.  Then I remounted the orange control unit to reground it.  Started right up.  Well....so far so good.  I guess time will tell.  How to regain trust?  lol

[dpixel]

UPDATE:  Problem still exists.  I tried grounding it with a wire.  I'm at a loss it comes and goes and makes no sense.  I have power going to it even when I loose spark from the coil.  Looks like it's the unit, so I ordered a new one....

I'm going to try this:  http://www.summitracing.com/parts/SUM-850018/   since it was on sale.   

[GN]

I had the same problem with mine. I reground a new module and used a wire ground from the module to the firewall. I also did that for all the ignition stuff. Starter relay too. Not the coil. I also replaced the battery cables. I have a stock system. Used the FSM to track it to the module. (carry spares) Now she starts rightup. I think what Nacho said is correct. Ground it good. And I also put in a higher cranking battery.

[dpixel]

Just got my new unit today.  I thought is was going to be blue as my link showed above, but it's orange.  I guess Summit matches the color.  I will have it installed in the next day or two and will keep the thread informed.

Anyway, my old MP unit was part of an electronic ignition conversion kit about 14 years ago.  Have these units had problems for that long?  Or is it just the newer ones?

@GN - What's the FSM?

[Nacho-RT74]

Factory Service Manual

I have known the MP units failures are more common on newer units but I got a missfail even not completely died on an older unit. The MP unit I got totalled was a newer unit.

went with FBO brand unit ( is now coming and somewhere between Miami and Caracas in the middle of the sea )

[dpixel]

Ok...tried again to start it with the old one.  It ran for 20 seconds and it died.  ... just to try it one more time.  Then I installed the new one and had it running for a half hour.  Perfect!  I'll be taking it out on the road tomorrow. I would have tonight but it was rush hour, besides I was having some beer.   

I might order another one of the Summit brands for a spare while they're still on sale.  I had a few more things to order anyway, but wanted to get this issue sorted out first

Another Charger on the road?  I'll know for sure soon.  I'll keep the thread posted.

Factory Service Manual?  I just have a Haynes manual.  Are the FSM's better?

And Nacho, I've heard about the FBO Brand.  Are they more reliable?  And where the hell is it coming from?    

[Nacho-RT74]

FSM is more technical, since is toward to dealers techs. Also is VERY specific for each model year... Haynes is very generic, and is good for those who only thinks on generic manteniance and basic knowledgement. If we are talking about the green Haynes book ( number 30050 ), I also have it. Is good too.

FBO brand I only have known good opinions about them, even racers, so after talk with the propper and direct seller, decided to go with it and give a try. They are in USA, I am the one who is not in USA

AAAAAAAAAAAAAAAAAND definitelly looks like you got an INTERNAL GROUND failure. No matter how much you try to fit a good ground to ECU housing, fail is internal. When my I get my Chromed MP unit fixed will show where and how to fix that at home

[dpixel]

I would say the problem is fixed.  The car performed great today...So this is a case where the symptoms were intermittent but got bad fast.

@Nacho - I'd very interested to see how to fix the internal problem.  Also, the FSM for my year would be really nice especially for 38 year old wiring.  I have a basic blue Haynes manual for 71 through 86 Chrysler Products.  It's ok for basic stuff but that's about it...Thank god for dodgecharger.com

Thanks everyone for the help.  What a great site!   

[GN]

I got my FSM from ebay. You will need a good automotive multi-meter too. I will also be looking for Nacho's repair.

[Nacho-RT74]

well not really MY repair... is a friend of mine who made to repair his orange unit on his 73 Charger. He removed all the backing isolation/seal then suposelly located the problem on an internal ground strap. Now with that he knows now WHERE exactly remove just a section of the backing isolation, add some soldering job and seal it back just at that location without mess with all the backing stuff.

that if of course if this fail IT IS SPECIFICALLY the problem, what I think it is.