Testing Ignition Coils

First task we had was to obtain two different ignition coils, and test them against specification. We hadto determine the part numbers, and search the spec sheets on google. Once that was completed, we set to testing.

My two coils were:

C6R-500
&
CTI-118

My test results were as follows:

C6R-500
Operating Voltage: 12v
Primary Resistance Specification: 1.20 - 1.50 ohms
Actual Primary Resistance: 1.3ohms
Secondary Resistance Specification: 6.5K - 8.5K ohms
Actual Secondary Resistance: 8K ohms
Earth leakage: OL

CTI-118
Operating Voltage: 12v
Primary Resistance Specification: 1.0 - 1.3 ohms
Actual Primary Resistance: 1.2ohms
Secondary Resistance Specification: 8.5K - 9.5K ohms
Actual Secondary Resistance: 9.33K ohms
Earth Leakage: OL

Both coils were in good condition and 100% serviceable.
If resistances were above specification, this may be caused by a break in the windings, and could result in incorrect charging and misfire.
If they were below specification, it may cause over heating and damge to other components.

My next task was to test a wasted spark coil.

I used a 6 output Coil from a Series 1 Holden Commodore 3.8l V6 89-90.
Part No: TIC032

I tested each of the three coils separately.

My results were as follows:

Coil 1 Primary: 1.2ohms
Coil 2 Primary: 1.2ohms
Coil 3 Primary: 1.1ohms

Coil 1 Secondary: 12.67K ohms
Coil 2 Secondary: 12.73K ohms
Coil 3 Secondary: 12.75K ohms

This coil pack was completely serviceable, as all of my reading came within, or near specification.

If either resistance was low, especially the secondary, it could mean there is a short circuit in the windings, and the coil will not operate correctly, if at all. If resistance was high, for example, OL, this could mean there is an open circuit in the windings, and the coil will not operate at all.

The next test was on Ballast resistors. I used two different Ballast resistors for my test.

Part No. BR1 and Part No. BR3. 

I had to obtain the resistance specification for each. These I found on a specification sheet stored with the resistors.

Specs were:

BR1 = .9 - 1.1ohm

BR3 = 1.5 - 1.7ohm

My readings were: 

BR1 = .7ohm

BR3 = 2ohm

Neither of these Ballast resistors were serviceable, as each was outside of their proper specification. Lower resistance may cause overheating of the coil and damage to the ignition components, while higher resistance may cause improper charging of coil and may lead to misfire, especially at higher RPM's