Taking Readings on Coils

[QB93Z]

I replaced the coils in my 1993 ZR-1 (110,000 miles) a few days ago. I did not have a specific coil failure. I am simply upgrading components to see if it makes a performance difference.

Now I am doing a research project using the take-out coils.

I have measured the primary and secondary resistance of all the coils to save as comparison data. For the primary side reading I had to insert a spade terminal into the slot to get a reading:
http://i407.photobucket.com/albums/pp152/QB93Z/Misc/DSC03618.jpg

On the primary side I got:

1-6 .9 ohms
4-7 1.0 ohms
5-8 1.6 ohms
2-3 1.5 ohms


Then I measured the seconday coil resistance:
http://i407.photobucket.com/albums/pp152/QB93Z/Misc/DSC03621.jpg

1-6 5.7 Kohms * Note: these are corrected values based on proper meter settings
4-7 5.6 Kohms
5-8 5.7 Kohms
2-3 5.6 Kohms

One thing that I noted is that when I measured the secondary coils resistance, the ~2.5 Kohm reading only was measurable for a second, then the reading went to open circuit:
http://i407.photobucket.com/albums/pp152/QB93Z/Misc/DSC03622.jpg

Now my questions:

Do these readings seem normal?

Has anyone else tried to measure the secondary coil resistance and gotten the change to open circuit indication after a second of measurement? Could it be a function of the digital meter I am using?

Jim

[ZRapid-1]

The meter is set for a full scale reading of 3.0 KOhms. That means it will measure resistances in the range from 0 to 3.0 KOhms max. Since the secondary coil resistance is greater than 3.0 Kohms, the meter is showing the max it can measure in that range.

Set the meter to 30. It will now measure up to 30 KOhms.

For a more accurate primary coil measurement, touch the end of the red measurement lead to the end of the black measurement lead. Record the reading and subtract it from all primary coil readings. The purpose here is to subtract the resistance of the meter leads (wires) and only record the coil resistance. The meter leads might only be a tenth of an ohm or two but will result in a slight measurement error at for low resistances.

[QB93Z]

Thank you. Good catch. I will give that a try.

Jim

[QB93Z]

I have taken the readings again using the proper meter scale and the secondary coil resistance is 5.6 to 5.7 Kohms.

Also, I agree about subtracting the lead resistance from the readings on the primary coils. It would be required for a more accurate measurement.

Thanks ZeeAreOne.

At this stage, I was hoping to find a go/no-go value for a faulty coil similar to the quick check I use to test injector coil resistance.

Does anyone have a "bad" coil that could be measured?

Jim