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Sarc
08-15-2003, 11:47 AM
I drive a '88 Mitsu with a turbo'd 2.6L 4 Cyl.

Recently, the engine started to drop out while I was maintaining a city speed (35 MPH).

Posted at the forums dedicated to the car, and one response talked about checking my spark plug wires and plugs.

For a unrelated reason, I decided to close the gap a little on my plugs just to see how the power felt at the high end.

To my surpise lately, the stumble I had been feeling around town, has been highly subdued.

I decided to check my coil resistance, which is a Blaster 2 coil run by a Digital 6 Plus.

According to the MSD web site the Blaster 2 and 3 coils should have the following resistances.

Pri: 0.7 Ohms
Sec: 4.7 K Ohms.

Last night after coming home from work, I checked the resitance of my coil with the engine still warm.

Pri: 1.0 Ohms.
Sec: 12.7 K Ohms.

I also checked the risistance this morning with the engine cold.

Pri: 1.0 Ohms.
Sec: 10.9 K Ohms.

This reading is alot different than what the MSD web site says, but oddly, it is closer to the specs that are shown for a stock coil in my vehicle. ???

If my coil is in fact bad, is there a common explanation for the readings I'm getting, or is it that it is just bad, and there is really no way to tell what caused it to die.

It is a older coil.
Came on the car when I bouhgt it, and it was on it when the previous owner bought the car as well, so at-least 2+ years old.

Thanks for reading.

msdtech1
08-15-2003, 06:13 PM
First, are you checking the coil with the coil wire still attached to it? If so, remove the coil wire and repeat the test. The specifications shown on our web site and in our current catalog are representative of what we are currenly shipping. If your coil is more than 2 years old I will need to go back and research what the specs on that coil where at that given time. I will see what I can dig up for you.

MSD Tech1

Sarc
08-17-2003, 06:01 PM
Thanks for the reply.

On the first test, I didn't pull the connector leads.

But, on the cold test, I did pull the leads to see if there was a difference in the readings and found none.
I got 10.9 K for the secondary resistance and 1.0 for the primary either way when the engine was cold.

I am posative that the coil is at-least 2 years old, if not older, so any info you can dig up would be greatly appreciated.

Again, thank you.

msdtech1
08-17-2003, 10:05 PM
The secondary resistance seems very high, but I will check that for you first thing Monday when we are back in the office. I should be able to tell you exactly what the resistance was on a coil that is over two years old.

MSD Tech1

msdtech1
08-18-2003, 04:53 PM
I looked back in our old coil spec sheets and the Blaster 2 Coils secondary resistance changed from 10,500 ohms to 4700 ohms at the end of 1998. Your coil has to be at least 5 years old or older.

MSD Tech1

Sarc
08-18-2003, 09:32 PM
Ok, given that, would you say my coil is good or bad?

Maybe a better question, is the resistance of the coil supposed to change depending on whether it is warm or cold?

msdtech2
08-19-2003, 09:16 AM
The coil resistance will change with temperature, so I would have to say that it is good. Although there are others tests, like inductance, current output and voltage output that also have to be checked and a load bank could only do this. If you have a different coil that you can try, try swapping them out.
Thanks,
msdtech2

Sarc
08-19-2003, 03:51 PM
Ok, cool.

Thanks for the clarification on the resisitance issue.
At-least now I know that a small variance in coil resistance is acceptable, but there are other factors that may not be seen and still mean a bad coil.

And msdtech1, thanks for digging up those older stats.

msdtech2
08-19-2003, 04:21 PM
No problem, and thanks for posting.
msdtech2