BMW e30s and several older vehicles that use a wire-on-plug system require the tip of the plug to be unthreaded.
This end of the plug can carefully be unscrewed by hand or with the help of some pliers.
The tip will look like this once the cap is removed, which should be just like how the plugs removed from the cars look.
The threaded male end of the plug can then be accepted into the sparkplug wire and will work as designed.
To shop for the correct ignition system parts for your vehicle head over to Fcpeuro.com and enter your vehicle into the fitment selector.
Once your car is added to the selector, there are a couple of important ways that we advise correct fitment.
The first is the "fitment indicator" shown on the Product Page after selecting a part. This box is below the "add to cart button" and has two states. It will either say " Yes this part fits" or "Part may not fit, click to verify".
Sometimes the green box will be accompanied by extra fitment notes. These notes may be independent of the information gathered by the vehicle selector. IE: VIN-specific options, need to be taken into account when determining overall fitment.