Tune up

Step 21 - After the coil mounting bolt is tight, reinstall the coil electrical connector and repeat this process throughout the remaining engine cylinders.

Reinstalling Coil Electrical Connector

Once completed, start the engine and observe the performance, if obvious problems exist retrace the pervious steps to discover a damaged spark plug, or ignition coil, or plug wire not correctly installed. 

Helpful Information

Vehicles are equipped with many different styles of ignition systems, but all follow the same principal. A tune up is needed between 35,000 to 75,000 miles depending on driving conditions and car manufacturers recommendations. Before starting, determine the individual tune up parts. When performing a tune up avoid contact with undesirable components such as exhaust manifolds, serpentine belts etc.)

Most spark plug gaps are pre-set and ready to install. Replace spark plug wires individually to avoid confusion, mark the wires clearly while confirming proper length of each wire, twist the wire boot to help break the seal which will assist in the wire removal. Inspect coil output terminals for corrosion as this will hinder performance.

The spark plug gap is important because it determines the amount of resistance used to "time" the ignition system. An incorrect spark plug gap can cause low power and poor mileage.

The condition called "coking" can cause stalling as well as variable idle ranges.

Best Practices

  • Remove debris from the spark plug well using compressed air.
  • Inspect the new spark plug porcelain and isolator before installing.
  • Use OEM (original equipment manufacturer) parts to ensure proper performance.
Related Car Repair Information


Written by
Co-Founder and CEO of
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-11-28)