Another intermittent shut down issue

[ronstory]

One other advantage of using a power resistor as a ballast resistor it get the heat outside of the coil. Plus those power resistor have cool heat sink fins.

[Peter]

Ron,

Interesting. Your experience is contrary to what is reported with A4 engines.

Adding EI resulted in many coil failures. The addition of a ballast resistor to reduce the current through the coil solved the problem.

I believe Moyer then sourced a coil that had the appropriate resistance for use with EI so that no ballast resistor is required.

I also note that the section you quoted from started as follows

WHAT TYPE OF COIL CAN I USE WITH THE IGNITOR? HOW DO I CHECK MY COIL'S RESISTANCE? (12V NEGATIVE GROUND ONLY)

To determine if your systems coil is compatible with the Ignitor, some measurements should be taken prior to installation of the Ignitor.

This suggests to me that they are pointing out that you need to keep the current down to protect the coil.

Regardless, keep the current down with EI or something will cook.

Peter

[ronstory]

Yes, but different environments with different requirements. I was not using an inexpensive coil but a Mallory Promaster... and that is the one brand/type of coil that I've never had failure no matter the heat, vibration ... nor impacts. Also the engine attached to it was nothing like stock, and around 60-70% more HP and spun to a redline 50% higher than factory. The engine has little in common with A4, other than a carb.

Yes, I have a hot rod IH, that engine might be able to do wheelie in a combine. ;^)

Now that coil is like $120 so 3-4x the cost of typical coil... but it met my requirements and is now almost 20 years old. Plus, the wedge mount is worth $20 of that for ease of install and removal when you need more access to the firewall. No complaints and I would buy another one... and I have... but not for my little A4.

[ndutton]

One other advantage of using a power resistor as a ballast resistor it get the heat outside of the coil. Plus those power resistor have cool heat sink fins.

???
It's excessive current coupled with twice the dwell of EI that heats the coil. Coils with sufficient internal resistance (I'm very careful how that is phrased*) for our application aren't subjected to excessive current so they don't overheat in the first place.

*Internal resistance does not mean there is an internal resistor present.

[ronstory]

Every bit helps. Having a 4 ohm resistor dissipating heat inside coil body just adds more energy that gets in way for the actual winding to cool through a case. Energy is energy.

[ndutton]

Having a 4 ohm resistor dissipating heat inside coil body just adds more energy that gets in way for the actual winding to cool through a case.

This discussion came up a year ago so I sacrificed a coil with internal resistance and cut it apart. No heat producing resistor inside. That is the point I was trying to make - - apparently poorly -- in my earlier post.

http://www.moyermarineforum.com/forums/showpost.php?p=117604&postcount=301

The resistance in an internal resistance coil is a function of winding wire gauge and length.

[ronstory]

OK, I have no desire to argue, that reminds me of work.

When I took apart a failed non MM coil for a different application, I found a resistor in a 3ish ohm coil (a loop of wire that was not part of the inductor). So both of us are stuck in small sample set that is not statistically significant.

That could be an anomaly in favor of the A4 world or not.

That said, my hypothesis are better coils (more expensive) are not the weak link in an pertronix system. But in an A4 with a $30ish coil... they are if you are at the 4 amp limit of IE, it is a question of your coil failing or your ignition.

We know which is cheaper to fix... so just buy a MM coil.

[thatch]

One part of this equation that has not been addressed is Muntasel's comment in post #1 about a possible charging system problem. If it is an over-voltage situation, along with it would come higher currents than normal. The Pertronix EI module has a built in breaker that will definitely shut it down and then reset itself once it has cooled down. This was verified by the factory while I was chasing down a very similar shutdown issue in an automotive application. I'd certainly make sure that the charging system was functioning properly before going any further.
Thatch

[Muntasel]

Well interesting discussion and references on the matter. I am very grateful for all of you sharing the knowledge.
Just to update on my last few days of trials...the bottom line is that the engine runs.
I first ran it at the dock A good 30’ at 2000 Rpm (no one was around!) cowling off looking for any sign of abnormality. I measured the tension at the primary with the resistor in place and it varied between 9.5V (idle) to 12V (2000Rpm) the feed come from external Alternator Voltage regulator. I believe those numbers are acceptable. Coil never felt hot and the engine never quit. The only abnormality however was a slight drop in power coincident with a Temporary decrease in fuel flow observed in the Clear inline fuel filter. So at this point I suspected a possible pump issue. The fuel filter stays half full most of the time.

Took the boat out carrying a spare coil and motored a 45’ to 1’ Hour Over the course of 2 days. No issues. On the engine at least (discovered a wobble in the prop shaft but that’s a different can of worms for a different forum ah ah).
Still perplex of what could have resolved the issue at least for now Other than connect and disconnect voltage regulator and wires to the coil.

Again thank you for your input it certainly Added a big piece of personal knowledge on this engine!

[roadnsky]

...discovered a wobble in the prop shaft but that’s a different can of worms for a different forum ah ah

Don't sell the gang here on MMI short...
Probably the best advice you can find on that issue will be right here! 😉

[Muntasel]

Gosh you are absolutely right! I just checked out some really good posts on the matter that gave me something to work on already!

[Zig Zag]

I would take a look at the Oil Pressure sensor connected to the fuel pump. I just had the same issue (engine died for no reason) when I bypassed that sensor my issue went away and was able to finish the trip without stalling again.