This is a spark plug wire separator holder for 8mm spark plug wires. Used this on my 2007 Ford Ranger 3.0 V6.

Print settings I used were .3mm layer height 75% infill with PLA+ (by ESUN)

Depending on actual spark plug wire, modifications may be required.

I used a lighter and bent it to make the diameter fit tight.

EDIT: PLA warps slightly in the engine bay so I would use a different material like ABS.