There are a few tutorials and guides out there, but they were only a little help when I was doing my conversion, so I wanted to write an easy-to-understand guide on my own. I did the conversion on an MY99 GC8 (EJ205) in this guide. I will leave the Subaru OEM part numbers as I go through the sections.
- Stalling
- Misfiring
- Rough idle
- Reduced engine power
- The engine vibrates more than it should
- Rough acceleration / feedback from the throttle
Please note that all of the above symptoms can also be caused by the spark plugs; you should also check them before proceeding.
Understanding this part will help you comprehend why there are only two signal cables and why we will pair the plugs in pairs.
A wasted spark system is an ignition system used in some four-stroke cycle internal combustion engines. In a wasted spark system, the spark plugs fire in pairs, with one plug in a cylinder on its compression stroke and the other plug in a cylinder on its exhaust stroke. Since one plug is fired on the exhaust stroke, serving no real purpose, the system was known as a “waste spark system.”
If you are looking for a fix and do not want to do a conversion, you can test your ignition coil system using the following method:
To test the coil pack, you can follow the steps outlined in the picture. If the coil pack is good, but your car is struggling to run, you can also try pulling each coil cable individually from the coil pack to see if the engine reacts in any way while the engine is running. If it does, this indicates that the coil cable is functioning correctly. If the engine does not respond, the coil cable is not working.
Before examining the pins of the sockets, let's understand the process we will follow. To complete the process, you will need to connect the signal, ground, and 12v cables in the correct manner. Once you have done this, you should be ready to proceed.
The front cylinders are 1 and 2, and the back cylinders are 3 and 4. Their locations and directions are shown on the coil plug as well.
The model of the coil pack shown in the picture is Diamond FH0161 (22433AA430).
From top to bottom, the pins are SIGNAL, GROUND, and 12V, as shown in the picture. The model of the coils I am using is Diamond FK0334 (22433AA561).
- You can use the top left pin 12V to power all of the coils.
- The top right pin is the ground and should be connected to the ground pin on the coils.
- The bottom left pin is a signal pin that should be connected to the coils on cylinder 1 and 2.
- The bottom right pin is the other signal pin, which should be connected to the coils on cylinder 3 and 4.
If you wish, you can purchase 4 of these connectors and connect the ground cable from the new coil you are installing (middle pin) to it. Then, you can place the connector under the bolt of the plug. Using this method will eliminate the need for the ground cable that comes from the ECU harness.
The accompanying pictures should provide sufficient explanation.
