B2200: Wrong Ignition Coil?

Model: 1987 B2200, Carb, M/T
Coil: Wells C819G (wrong), C1114 (correct)
Symptom: Misfires on hot days under heavy load (uphill)

I bought a new ignition (C819G) coil but I think it might be wrong for this truck. It says on the coil: "12V Use with Primary Resistance Wire or External Resistor". I looked at the wiring diagram and I see no resistor in the ignition circuit. Anyone know if there is a resistor in this ignition wiring? Will I damage this coil if I use it on this vehicle?

Also:
I meas. the primary coil on the old: 1.0 ohms, new coil: 1.2 ohms
so, I'm thinking I wont burn up the primary winding on the new coil 'cuz it has slightly more D.C. resistance. Hmmm.....

I appreciate any info.

It says on the coil: "12V Use with Primary Resistance Wire or External Resistor".

This comment can be read two ways. It seems to say either way to use?

Do you have a picture of your original set up?

Some ignition coils come with internal resistors. Back in the old school days the external resistor was a porcelain piece where the wire sits on to provide the external resistance before the + side wiring of the ignition coil...

OK, here's a pic of the coil.
As you can see, there is no visible resistor on the (+) side (right) of the coil. Is the hot wire a resistive wire? I have no idea.

Note: That thing down on the left and below attached to the front of the engine wall I decided is a capacitor (probably for noise suppression and it goes to the (-) side of the coil).

So the bottom line is, according to the coil instructions is that you must have either a resistive wire feeding the coil, or an external resistor. Either of these options would drop the voltage going to the coil. Is there already a resistor or resistive wire designed into this circuit? I have no idea.

As I mentioned above, the primary coil resistance (of new coil) is slightly more than my old coil, so I have a hard time believing I will fry the new coil. But hey, what do I know?

Did you specify the year and engine model of your truck when you purchased the ignition coil? The parts person should know what your model year uses.

I have an 88 B2200 Cab Plus 5 speed MT and my ignition coil is an MSD type with an internal resistor.

My trusty little yellow paperback Mazda shop manual is for the 1988 B2600 and 1988 B2200 models. It doesn't show an external resistor used for the B2200 in the wiring schematic. What is interesting is the B2600 does use an external resistor which shows in the wiring schematic.

The picture you provided is similar to my wiring and my B2200 doesn't use the external resistor anywhere close to + side of the ignition coil.

If you trust the resistance reading of the two coils that difference shouldn't hurt anything.

Ya, this one obviously does not have an internal resistor.

Thanks for the info Cab+. There was no parts person, just the listed coils for my year and model on the RockAuto .com website. Who knows if they're right. So now I wonder if this coil is really for the B2600 or some other model.

I'm glad I got cold feet on this coil before I installed it. I called Wells Vehicle Electronics this a.m. and inquired about this coil. The parts guy - after much searching of tech info. , finally found some specs from Mazda. Bottom line: this C819G coil is not spec'd for my vehicle. The Wells part# he found is C1114 and it states "For use with transistor ignitor" (my vehicle has this) written on the coil. He apologized for the wrong part listing at RockAuto. He did say the one I had might work, but he would not suggest trying it.

Thanks to Cab+Rider for your help.

It probably would work alright, but if you can get an exchange then that would be the better path.

I have used MSD Blaster 2 coils without incident in both the 2.0 and the 2.2, carby and EFI. When all else fails you can do the same.

Hey emjay,

Is there a noticeable difference when changing from a factory coil and MSD Blaster or comparable coil? My Truck is a '92 EFI 2.2. I haven't had an issue with my stock coil but I am interested to see if there is any noticeable gain from going to an aftermarket coil.

Would it be worth it to me to change out my currently working stock EFI Coil?

Thanks

Spacemonkee, you wouldn't notice much difference in my opinion on stock coils to an aftermarket one, unless you plan on running a whole new ignition setup would be the only noticeable gain and very minimal at that, most upgraded coils are just for more performance enhanced engines. it wouldn't hurt a thing to do it, but i doubt the gin would be worth the money spent. a very minimal gain if any.