Honda S2000 Spark Plug and Ignition Coil Replacement

Recently, the check engine lamp flashed several times while driving S2000. The auto dealer’s mechanic confirmed that the engine was misfiring. The cause of the misfire has not been identified, but decided to replace the spark plug and ignition coil to eliminate the possible causes.

First, remove the plug cover and remove the ignition coil and plug in this order.

Check the removed spark plug. The condition of the plug is better than I expected. However, the gap was about 1.3mm compared to the new 1.1mm. It was almost limit value.

Comparison of old and new plugs. An old one is the NGK Iridium MAX. It is a long-life plug, but it seems that it has reached the end of life at 30,000 km. A new one is DENSO iridium power. The new plug is not a long-life type, so I think that I have to replace it within 10,000 km.

This is a new ignition coil. The genuine product is expensive, so I choose compatible product. Made by HITACHI. For F20C, you should choice “U14H01-COIL”.

Comparison of old and new ignition coils. The genuine ignition coil is made by Denso. The plug entry is brown and dirty.

Install the plug and tighten it to the specified torque. The S2000 service manual says 18 N・m, but the DENSO manual says 20 to 30 N・m. This time it was tightened to 25 N・m. After installing the ignition coil and replacing all four, attach the plug cover to finish.

Just in case, I reset the ECU. To reset the ECU, remove the third 7.5A fuse from the top on the right side, and return it to the original after 10 seconds or more. Then start the engine and leave it idle for a while to learn. This is all the work.

After replacement, the idle became stable and the engine became smooth. It feels like it has increased power, and it feels like turning without stress. I hope that the check engine light does not show up after that.