Tune-Up - Minor

This minor tune-up procedure includes replacing spark plugs, inspecting ignition coils, replacing engine air filter, and inspecting cabin air filter to maintain optimal engine performance and fuel efficiency.

Warnings

Tools required

Parts

• Spark plugs (Iridium) × 4 — 90919-01253 or equivalent NGK/Denso iridium
• Engine air filter × 1 — 17801-0P051 or equivalent
• Cabin air filter (optional) × 1 — 87139-02090 or equivalent

Preparation

1. Ensure engine is completely cool to the touch
2. Park vehicle on level surface and engage parking brake
3. Turn ignition off and remove key
4. Open hood and secure with prop rod
5. Locate spark plug cover on top of engine (plastic cover with 'Toyota' embossed)
6. Gather all tools and parts within easy reach

Procedure

1. 1

   Remove engine cover and air intake components
   Remove the plastic engine cover by pulling upward firmly - it is secured by rubber grommets only. Set aside. Disconnect the air intake tube from the air box by loosening the clamp at the throttle body side. Remove air box lid by releasing clips.
   Torque spec

   Air Box Clips5 Nm (4 lb-ft)
2. 2

   Inspect and replace engine air filter
   Remove the engine air filter from the air box housing. Inspect for excessive dirt, oil contamination, or damage. Clean any debris from the air box housing with a shop towel. Install new engine air filter ensuring it seats properly in the housing with the airflow direction arrow pointing toward the engine.
3. 3

   Access spark plugs and ignition coils
   Locate the four ignition coil-on-plug assemblies on the top of the cylinder head. Each coil has a 10mm bolt securing it and an electrical connector. Label or photograph the coil positions if desired, though they are identical and interchangeable on this engine.
4. 4

   Disconnect ignition coil connectors
   Press the locking tab on each ignition coil connector and pull straight up to disconnect. Do not pull on the wires themselves. The connectors may be stiff; use controlled force and wiggle gently if needed.
5. 5

   Remove ignition coils
   Using a 10mm socket, remove the single bolt securing each ignition coil. Pull each coil straight up with a twisting motion to break the seal. Inspect each coil for cracks, carbon tracking, or oil contamination. Inspect the coil boots for tears or damage. Clean any debris from around the spark plug wells using compressed air or a clean shop towel.
   ⚠Do not allow dirt or debris to fall into spark plug wells. Cover open wells with clean towels if working on one cylinder at a time.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
6. 6

   Remove old spark plugs
   Using a 14mm spark plug socket with rubber insert and extension, carefully remove each spark plug by turning counterclockwise. Keep spark plugs in order if you wish to inspect them for cylinder-specific issues. Inspect old plugs for abnormal wear, oil fouling, or carbon buildup which may indicate engine problems.
7. 7

   Prepare and gap new spark plugs
   Verify the spark plug gap on all new plugs using a spark plug gap tool. Factory specification is 0.043 inches (1.1mm). Adjust if necessary by carefully bending the ground electrode. Do not touch or disturb the center iridium electrode. Apply a thin coat of dielectric grease to the inside of each ignition coil boot to prevent sticking and aid in future removal.
8. 8

   Install new spark plugs
   Thread each new spark plug by hand into the cylinder head to prevent cross-threading. Once finger-tight, use the torque wrench and 14mm spark plug socket to tighten to 18 Nm (13 lb-ft). If a torque wrench is unavailable, tighten 1/16 turn past finger-tight. Over-tightening can damage the aluminum cylinder head threads.
   ⚠️Spark plug torque is CRITICAL. This specification is 18 Nm (13 lb-ft) for this engine. Over-torquing will strip aluminum threads; under-torquing can cause plug ejection and catastrophic engine damage.
9. 9

   Reinstall ignition coils
   Install each ignition coil by aligning it with the spark plug and pushing down firmly until it seats completely. The coil boot must engage fully with the spark plug terminal. Install the 10mm mounting bolt for each coil and torque to specification.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
10. 10

    Reconnect electrical connectors
    Reconnect the electrical connector to each ignition coil, pressing firmly until you hear and feel a distinct click. Tug gently on each connector to verify it is locked in place.
11. 11

    Replace cabin air filter (optional)
    Open the glove box and remove contents. Press inward on both sides of the glove box to release the stops and lower it fully. Remove the cabin air filter cover by pressing the tabs. Slide out the old cabin air filter, noting the airflow direction arrow. Clean the housing if needed. Install the new cabin air filter with airflow arrow pointing toward the blower motor. Reinstall cover and glove box.
12. 12

    Reinstall air intake and engine cover
    Install the air box lid and secure all clips firmly. Reconnect the air intake tube to the throttle body and tighten the clamp securely. Reinstall the plastic engine cover by aligning the grommets and pressing down firmly until it clicks into place.
    Torque spec

    Air Box Clips5 Nm (4 lb-ft)

Reassembly

1. Double-check that all ignition coil connectors are fully seated and locked
2. Verify air intake system is completely reassembled with no loose clamps
3. Ensure no tools or parts are left in the engine bay
4. Close hood securely

Verification

• Start the engine and verify it starts normally without extended cranking
• Listen for smooth idle with no misfires or unusual noises
• Check for any diagnostic trouble codes using an OBD-II scanner if available
• Rev engine gently to 2000-3000 RPM and verify smooth acceleration with no hesitation
• Verify no vacuum leaks by listening for hissing sounds around air intake connections
• Test drive vehicle for 5-10 minutes to verify normal operation and acceleration
• After cool-down, visually inspect for any fluid leaks or loose connections

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