How to Change Spark Plugs in a Toyota 4.7 Liter Engineby Cayden Conor
The Toyota 4.7-liter engine uses a coil-on-plug system. This means that each spark plug has its own coil. The coil sits on top of the spark plug, eliminating the need for spark plug wires. Spark plugs should be replaced according to your maintenance schedule, even if they do not look like they need to be replaced. Always replace all eight spark plugs at the same time to ensure optimal engine performance.
Remove the wiring harness connector on each of the coils by pressing in on the plastic tabs and pulling the plug off the coil. Working with one coil and one spark plug at a time, unbolt the coil and pull it off the engine.
Remove the spark plug using the 16-mm spark plug socket. Insert a spark plug into the spark plug hole and start turning it by hand. After four or five turns, use the socket to tighten it firmly, but no more than 13 ft.-lbs. of torque. Do not overtighten the plug, as you could crack the porcelain.
Replace the coil, tightening the bolts firmly. Plug the wiring harness connector in. Repeat the process for all eight plugs.
- Always start the plugs by hand. The heads are aluminum and easily stripped if the spark plug is not centered properly in the hole.
- The gap is 1.0 to 1.1 mm. Plugs come pre-gapped from the auto parts store, but they should always be checked in case they were dropped.
Things You'll Need
- Set of sockets
- 16-mm spark plug socket
Cayden Conor has been writing since 1996. She has been published on several websites and in the winter 1996 issue of "QECE." Conor specializes in home and garden, dogs, legal, automotive and business subjects, with years of hands-on experience in these areas. She has an Associate of Science (paralegal) from Manchester Community College and studied computer science, criminology and education at University of Tampa.