Spark Testing

Testing an ignition coil output on my 944 Race Car

After having diagnosed a few no starts lately – the latest being my 9444 race car – I decided to get a spark checker to verify the output of the ignition coil.

To test the 944 coil I removed the coil wire from the distributor and connected the wire to the tester.  I grounded the clamp to a bolt near the headlight.

I then connected one wire of the remote starter to the starter solenoid and the other to the positive terminal of the battery.

I then turned on the power to the car and the ECU.

I was able to then monitor the spark tester while spinning the starter.  

I started with the tester spaced at a little over 20,000. I got a good visible spark so I opened the gap some.  I still got a big spark so I opened it up a little more. This time the spark bypassed the tester and jumped to the exposed parts of the car that the tester was resting on. I repositioned the tester and opened it up all the way to 40,000. I was able to get a good visible spark indicating that the coil was firing at its full potential.

This made for a quick and easy test of the ignition system.  I could easily connect it to a plug wire to make sure the individual wires are working as well.  I think this will make a good addition to my troubleshooting toolbox. 

When I went to start the car later, there was a lot of black smoke coming from the exhaust.  I am sure that while I was spinning the engine over with ignition disconnected the injectors were pumping in fuel.  It might be a good idea to disable the fuel pump when performing the spark test.