Bad Hub Magnets - 1998 Mercury Mariner 175hp 2.5 V6 EFI

[Soporific]

Sorry, I don't think that patent is helpful. It doesn't seem to be the right one.

[Soporific]

PanRonnie, The fridge magnets are too simple a design and won't keep the trigger voltage from swinging in the wrong direction right after the correct voltage spike to trigger the correct switch box. It seems that the magnets have to be semicircular with the poles on the outer and inner faces so that the trigger coils only pike in one direction at the change of one field to another. Hard to replicate that. Now if the trigger had six coils...... then diodes could cancel out the negative part of the voltage and only one fridge magnet would be required on the hub. But then Mercury would sell a lot less flywheels.

[H2Okie]

Looking at the CDI push /pull hub magnet configuration and the theory of operation diagram for the ADI ignition system it looks like the positive pulse from the trigger coil "forward biases " the gating diode controlling the the "switch" (probably a transistor ) in the switch box to to fire it's respective ignition coil . This is followed up with an immediate negative pulse to the gating diode "reverse biasing" it to turn it "OFF" . This negative pulse energy now blocked by the switch gating diode then flows through another diode that is only forward biased on negative pulses to the bias circuit and allows the negative pulse to combine with negative pulses from the other switch box and drain to ground via a capacitor .

[Soporific]

Actually, Pan, now that I think about it, there is probably enough room under the trigger coils to attach another three coils and use a small bar magnet to trigger all six in one revolution. I would need a 3 cylinder or 6 cylinder trigger assembly, a bar magnet and six diodes to try this out. Still a very cheap and permanent fix. Anyone care to donate a used one if I pay the shipping?

[Soporific]

H20kie, I know that the trigger voltage is for opening a SCR gate and the negative swing should not be there until 180 rotation has occurred. That is the problem with mine. Any negative swing on the trigger immediately after the proper trigger is positive for the other switch box and it fires the other cylinder. For example, after 1 fires, then the negative swing fires 4. This is my problem. The magnets are degraded and not as they should be anymore. The push pull design limits the negative swing but also boosts the voltage at low rpm. If you look at the video, and compare it to my scope you will notice that mine has no delay whereas in the video there is a null in between the triggers. That is what I wish I had.

[Soporific]

My basic understanding regarding the excess voltage generated by the trigger coils is that due to the rather low threshold to fully open the SCR and the wide range of rpm for the motor from pull start to WOT, a bias circuit was necessary. As the rpm increases, the timing would also advance as the voltage in the trigger coils rises unpredictably. All of this extra voltage is not required and only causes timing problems so the bias circuit is necessary to trim the trigger voltage down and thereby keep the timing in control. So even if I add three coils to have six trigger coils and then have one for each cylinder (yes), the bias circuit is still necessary.

[Soporific]

Does anyone see any potential problems with the six coil design? I like the simplicity of one trigger coil per cylinder and only one damn magnet on the flywheel hub for the trigger assembly. Please critique.

[PanRonnie]

you could install an OMC ignition as i believe that works as you would like
also have the theory that if you disconnect the power coil from the power-pack you would disable the rev limiter
as there would be no frequency input into the power-pack
it would still be powered from the 12 volt feed from the ignition switch

[PanRonnie]

For some reason this just seems easier!?
https://www.ebay.com/itm/Mercury-200...-/112569766328

[Soporific]

For some reason this just seems easier!?
https://www.ebay.com/itm/Mercury-200...-/112569766328

YES, of course it does No returns no warranty and I have done this already. My "new" flywheel is in much better shape than the one on the listing. Yet the magnets have gone bad. Another 200 plus, no thanks. I won't sell mine to some unsuspecting person either. Hard to prove a defect with magnets and warranty. My choices seem to be dealer at over 500 or fix it differently and permanently. I bought another trigger coil assembly and will mount it on top of mine with some mods and a couple of neodymium magnets epoxied on the hub. As time goes on, I think more of these rubber hub magnets will go bad. YMMV. If it works well for me, others could do it too. We will see....

[nitro_rat]

I haven't experienced this particular magnet failure and some of the flywheels I run are over 40 years old. If you hunt around you can find one cheap or free...

I usually prefer the simplest solution to a problem but if you're just designing a new ignition system as a hobby I say have at it...

[H2Okie]

Soperific , If you are hell bent on reinventing the wheel you should check out the nifty little controller made by "Speeduino " that allows the user to set up ignition and or fuel injector timing for engines . Though the price is pretty low considering what it can do a used flywheel is probably still the cheapest option .

[Soporific]

I haven't experienced this particular magnet failure and some of the flywheels I run are over 40 years old. If you hunt around you can find one cheap or free...

I usually prefer the simplest solution to a problem but if you're just designing a new ignition system as a hobby I say have at it...

Are these 40 year old magnets made of the rubber magnet material that has failed on two of my flywheels? I prefer the simplest solution too. I'm not sure where to hunt around to find these flywheels in my area, maybe it is easier for you. Maybe I have had very bad luck with flywheels, but two in a row is a bad experience. It is good to hear that a cheap and simple solution SHOULD exist for me. I thought Dave S. was going ship me one......

[Soporific]

Soperific , If you are hell bent on reinventing the wheel you should check out the nifty little controller made by "Speeduino " that allows the user to set up ignition and or fuel injector timing for engines . Though the price is pretty low considering what it can do a used flywheel is probably still the cheapest option .

I am not hell bent on anything, in fact, if I could get some of the dealers around here to even call me back with a price for 271-859238T16, I might have already sold the farm and bit the bullet with a new flywheel. I am not trying to reinvent the wheel. Maybe I am too cheap or just frustrated to see parts discarded for some minor defect that you can't even see. Either way, I don't think I will be trusting another flea bay flywheel. Other than that, not much choice around here. Spend a year hunting to find one really cheap or free? I don't want to wait that long. Am I curious to see if I can easily mod the trigger coil assembly ONLY, yes, definitely, but not if I can get a reasonable replacement flywheel.

[nitro_rat]

Never really paid any attention to the magnet material. I only run the old style 9/16 amp systems. I have a couple 40 amp wheels kicking around though...