Problems with MSD ignition?

[jeffp]

Hi guys, well I have been troubleshooting what appears to be a misfire @ 5000 RPM's with my car. I am running a MSD 6A trigger box, and I had the HVC coil on the system.

I first thought it was a problem with the coil, and I believe I was correct in that find.

I then started looking around for another coil because this was the second failure in about 15K miles run time on the system. I called MSD customer service and they said it was a problem with the car. I disagree with their assessment of the problem. I had a number of guys look at the car, and none of us could find what we would consider a trouble area of the high tension side of the ignition.

I decided to go with the sure never die old MALLORY Volt Master Mark2 coil. I thought for sure this would cure my problems. Well it did not. I am sure the MALLORY coil has more then enough poop to fire the engine under boost.

I run the car and decide to data log the situeation, and sure enough the mixture goes very lean. So now my trouble shooting is leading me to do two things.

1) replace the cap and rotor. I checked the wires and they appear to be in good order.

2) run the car like stock with a really hot coil and see what the outcome is.

 

The question I have for all of you is, have you ever had a failure of the 6A triggering box from MSD? Any input would be appreciated.

[fastzcars]

How are you getting the signal from the distributor to the MSD box? I think the signal wiring should be sheilded from the sprark plug wires, or your get a missfire. I think the MSD manuel says to run the wire down the firewall to to keep it from getting stray signals.

[jeffp]

I have been running the car the same as when I first installed it. The box is mounted where the A/C cooling fan was mounted.

The power is run along the passenger frame rail. The trigger is run down the radiator support and to the stock location as the coil was in the car.

the trigger for the box comes from the power transistor, from the stock system. This is the ECCS system like on the 300zx cars.

[Mikelly]

Couple of things I'm aware of with these boxes...

 

Moisture is not your friend, first and foremost and Vibrations are second in causing solder joints to give under vibration. MSD boxes are great until they start acting up and then they are junk... Mount it in a solid place, mounted away from rain potential. And while you're at it, shield all the wiring when possible because those issues are also known. Your box may be the issue. Try running the coil without the MSD and see if it runs well without misfire... THAT will tell you if the box is bad or not.

 

Mike

[jeffp]

I was thinking about it all night, sleep thought so fun LOL. Anyway, I am going to hook the soil up directly like the stock configuration and see how it goes. I am guessing that my problems will go away. I will post my findings, you know the only reason I installed their box was for two reasons.

1) to power their HVC coil.

2) to give me the three sparks for engine speeds up to 3K RPM's

I felt the additional sparks would be helpful for fuel economy.

[dapiper]

In 10 years I have replaced one coil (stock, they dry out being mounted horiz), three trigger pickup coils (vibration intermittant), and two MSD 6T boxes (?).

[yo2001]

what kind of plugs? and gaps? I assume BPR7ES at .02x"? I know MSD has a dwell control which can do stuff wierd. I think the signal going into MSD has to have small charge time or it'll overload on dwell cause the coil or ignitor to run hot. Heat sinking the ignitor suppose to help. Anyhow I would takeout the MSD and see if the problem goes way.

[jeffp]

I have two problems with the car. The first was the HVC coil was arching out creating a weak spark. So that was replaced with the MALLORY coil.

Second problem, and I verified its disruption with the ECU was my new, well for the most part, electric cooling fan.

So between the two of them the car would not like RPM's over 5K the weak spark under boost and the fan noise introduced into the electronics. Seems I was getting some good level ov spurious voltage spikes created by the fan, and the noise level of the moter also 150-200 millivolt noise floor is at the correct frequency, that when the trigger from the distributor got to 5K the ECU lost the correct signal and then tried to trigger off of the noise from the fan, the car died at that point and it appeared to be a misfire of the system, which it was, but in a direction that made it difficult to troubleshoot.

I did end up running the car like the stock ignition with the power transistor directly to the coil. I did note the loss of RFI in my stereo amplifiers, and the car seemed to run more smoothly at idle.

So liking simplicity, I just may remove the MSD equipment all together, I figure if I dont need it then why use it. That just equates to one more potential failure in the future.

anyway, I just thought some of you may be interested in the investigation. I have a suppression/filter circuit I have come up with that has reduced the noise floor to about 20 millivolts, well within tolerances for filtering. I think I will go ahead and make a circuit board for the components and the power cables for the fan and be done with it.

[fastzcars]

Good going jeffp. Glad to hear you figured it out. Thanks for posting your results and remedies.

[EZ-E]

So then the question begs to be answered, on a high hp l series motor, do you really need the additional spark from the MSD units?

 

Would that be a no to what you have found out here Jeff?

[jeffp]

I think I can answer that question well enough.

There are a few things we need to realize about the MSD boxes, and coils in general.

The MSD coil was key for me, because I needed a higher current spark under boost conditions. I looked around for coils and the first thing I looked at was the mallory coils, why, because I use to work for them. I was well aware of the coils they produced, but I also was aware of the fact that the coil I wanted for the application was not available any longer. The MALLORY voltmaster mark 2 coil would have fit the bill without any question. At the time I could not find one, new or used. Now there is Ebay, and I found three units and bought two. Keep in mind though, I have since found out the Voltmaster coil underwent a change in the early 80's due to manufacturing costs that basicall took a bullet proof coil and turned it into a not to great of a coil. Seems they decided to change the gauge of wire used to turn the coil, and they then became failure prone, where as before they NEVER went bad.

So for me MALLORY was out, because I never did like the promaster, and that line of coils. Those units were designed for the Hyfire boxes, and I know for a fact they were having reliability problems with the Hyfire boxes.

Then I learned about MSD, and I took a look at what they were selling and they advertised basically the equilivant setup. The coil specs were very close to the mallory part. I then took a look at the 6A box and liked the things like multi spart the unit would do. I went with the basic ^a, I did not want rev limiting of all of the bells and whistles, but just a box that would fire the coil under high compression.

Then I had a failure of the coil just about the time I installed it. The steel core around the coil was zapping me every time I touched it. Well with anyone that has had the electronics background, like me, voltage on the csteel core of the coil meant it was shorting, or arching out. I sent it back and got a new one. The one thing that did bother me about the 6A box was that it had RFI leakage, I could hear the coil firing in my radio. But I could live with that and I did until the second coil failed, and I took that unit apart, after my conversation with the customer service weannie that told me there was something wrong with my car. I found where the coil was arching out, and I could see it at night when the car was running.

So I still have the 6A box, and it is still noisy, and I have run it with the voltmaster coil. When I still had problems, I decided to run strait from the power transistor, and figured if the resistance of the primary wingings of the voltmaster was to small, all that would happen is I would blow out the power transistor. Since I had three parts, I ddecided to go for it and see what happens. Guess work here, as I have yet been able to get a good part number of the transistor to use as a reference to determine just how much current it could handle. The power transistor worked. I checked the case of the transistor while the car was running to make sure it was not getting hot, which would indicate the current capabilities of the part were being taxed. The transistor was not hot so I did a run, hooked up basically stock, but with the voltmaster. The car still bucked, I turned off the electric fan and it bucked hard once, I tried it again and it was much better. I still haden't gotten the RPM's up enough since the first fire to enable the ECU to learn the engine requirements.

Now Accel, makes a very hot coil, and the specifications are again VERY close to the voltmaster coil. that part has not come in yet. Accel makes some very good parts, but I never liked their configuration, at least in the case style department, so I never used their products.

So those are the BIG three, and incidentally, NISSAN made some very hot coils for their turbo 300zx applications. I have not tried any of the Nissan parts.

Now it seems according to a company in Ausyland, that AFTER 2003, some manufacturers have again gone back to the high tension, heavy gauge coil wire and the car coils are getting much better. I think because now we have more capacitive discharge units in just about every car now, so long to the old points type configurations.

The multi spart function, well there again it is not required, and if I had the time to actually test that function, I am just about sure it does nothing for spark and the ability to ignite fuel, possibly for fuel economy under light loads, but then by that same token, they ALL OF THEM, only work to 3K RPM's and revert back to one spark per one combustion cycle. So you tell me, is it worth the $250-350 investment that I made like many others, for a multi spark system, that will not take you to redline, and has some questionable effectiveness in the first place?

I will say one thing though, I also found out that Electromotive used the MSD boxes, and come to find out, when they got a new box, they tore it apart and rebuilt it to their specifications. So go figure! I think I am goingto research out that aspect of the ignition system and see what I can dig up. I am curious as to what changes they made, and if I can find out that information I will let everyone in on what was changed, and more importantly, WHY. I can tell you this, the MSD setup I was running, with stock plug gap, was prone to misfires. I had to set my plug gap to .025 to stop the misfiring, so again you tell me, was it worth the money. I say I dont think so at this point, with the testing I have done thus far. I do have some possibilities of testing the coils under extreme pressures, and I just may check that out as well, just for my own interest in the matter.

So there you have it. My recommendation is, that if you don't have any problems, then leave it alone, and if you do have problems, then check out your current system and make sure it is operating correctly befor you spend your hard earned money on all the fancy boxes out there.

Myself, I am sick to death of dealing with products that are advertised to do X only to find out later they will not actually do X or if they do, it is short lived.

Thats my story and I'm stickin to it LOL. Have a good one guys and gals. Now I have a circuit board to make.

[datsunan]

I am having a similar problem with my car but I have a mis right off idle and it seems to become less noticable at higher rpm. I also have the msd 6a and an electric fan but have had both for some time and only recently started having problems with a mis fire. I bought a MSD blaster coil, new wires, plugs, cap/rotor and still have it. Is it the signal wire from the msd that is picking up rf? What if it is run alone? I have noticed a change in Idle when my fan kicks in but thought it was due to a voltage change to the coil. I guess the easy thing to do is go back to basics with the stock set up. Is your problem fixed? It sounded like you were not so sure it was 100%.

[jeffp]

I guess the very best way to see what is happening is to put an oscope on the motor b+ line and ground, to see if there is noise coming from the motor. I was looking at about 150millivolts of noise coming off the motor. For the majority of the electronics out there that noise floor will kill the operation at some point. When you stop to think that a standard radio picks up a signal from the air in the 113-120Db range(about .3 millivolts) one can reconize the problem quickly.

You know, the more I work with the Nissan ECU the more respect I have for the unit. I think they did an excellent job on the box and most people, myself included introduce problems with all the new fancy crap that is being marketed.

I havent had the chance to do any further work on the car here the last few days, between being sick, and the computer for the wife dieing I have been a little busy. Got to keep the wife happy, besides she gets on MSN for a long time that gives me time to do the car thing in the garage LOL.

 

Is it the signal wire from the msd that is picking up rf? What if it is run alone?

The MSD box is a noise maker period! I would like to take the time and tear one apart to see just how they made the unit. Coming from a radio background I reconized the noise the thing produced from day one. I just decided to deal with it by not dealing with it. I did not want to start screwing with their product, but yes the 6A makes noise. I did not have problems with it interfearing with the ECU, but it can be as simple as running their wires differently that will make it screw with the ECU. I would go back to stock and see what you get, and go from there. I like you also got new cap/rotor, but I have not installed them yet. I will get this thing resolved this weekend.