This minor tune-up procedure includes spark plug replacement, air filter replacement, cabin air filter replacement, and general engine inspection for a 2015 Kia Forte with 1.8L I4 engine.

Warnings

Tools required

Parts

• Spark plugs (NGK or equivalent) × 4 — 18854-10060 or equivalent, gap 0.039-0.043 in
• Engine air filter × 1 — 28113-2H000
• Cabin air filter × 1 — 97133-2H001

Preparation

1. Ensure engine is completely cold to the touch
2. Park vehicle on level ground and engage parking brake
3. Open hood and secure with prop rod
4. Gather all tools and replacement parts

Procedure

1. 1

   Remove engine cover
   Remove the plastic engine cover by pulling upward firmly on the front edge, then the rear. The cover is held by rubber grommets and may require moderate force. Set aside in a clean area.
2. 2

   Replace engine air filter
   Locate the air filter housing on the driver's side of the engine bay. Release the clips securing the air box cover (typically 4-6 clips around the perimeter). Lift the cover and remove the old air filter element. Inspect the housing for debris and clean if necessary. Install the new air filter ensuring proper seating with the arrows indicating airflow direction pointing toward the engine. Secure the air box cover and ensure all clips are fully engaged.
   Torque spec

   Air Box Clips5 Nm (4 lb-ft)
3. 3

   Access cabin air filter
   Open the glove box and remove contents. Locate the glove box stoppers on both sides (small tabs or arms) and squeeze or press to release them, allowing the glove box to drop down fully. Behind the glove box, locate the cabin air filter access cover.
4. 4

   Replace cabin air filter
   Remove the cabin air filter cover by pressing the release tabs on both sides and pulling it out. Slide out the old cabin air filter, noting the airflow direction arrow. Clean any debris from the housing. Install the new cabin air filter with the airflow arrow pointing in the same direction as the old filter (typically toward the interior). Reinstall the cover until tabs click into place. Return glove box to normal position by reversing the removal process.
5. 5

   Remove ignition coils
   Locate the four ignition coils on top of the engine. Disconnect the electrical connector from each coil by pressing the release tab and pulling straight up. Remove the single bolt securing each coil using a 10mm socket. Pull each coil straight up and out of the spark plug well with a gentle twisting motion. Inspect coil boots for cracks or damage.
6. 6

   Remove old spark plugs
   Using a spark plug socket with extension, carefully remove each spark plug by turning counterclockwise. Keep plugs in order if you want to inspect them for cylinder-specific issues. Check the electrode condition and gap wear on old plugs to assess engine condition. Ensure no debris falls into the spark plug wells during removal.
   ⚠If plugs are difficult to remove, do not force them. Apply penetrating oil and wait, or seek professional assistance to avoid damaging threads
7. 7

   Prepare and gap new spark plugs
   Remove new spark plugs from packaging carefully. Using a spark plug gap tool, verify the gap is set to 0.039-0.043 inches (1.0-1.1mm) as specified for the 1.8L engine. Adjust if necessary by carefully bending the ground electrode. Apply a small amount of anti-seize compound to the threads (avoid getting any on the electrode). Apply dielectric grease to the inside of the ignition coil boots to prevent moisture intrusion and ensure good connection.
8. 8

   Install new spark plugs
   Carefully thread each new spark plug by hand into the cylinder head, turning clockwise. Thread at least 3-4 full turns by hand to ensure proper thread engagement and prevent cross-threading. Once hand-tight, use the spark plug socket and torque wrench to tighten to 25-30 Nm (18-22 lb-ft). If a torque wrench is unavailable, tighten 1/16 turn past hand-tight for new plugs with crush washers.
9. 9

   Reinstall ignition coils
   Insert each ignition coil back into its spark plug well, ensuring it seats fully onto the spark plug terminal. There should be a positive click or firm seating. Reinstall the mounting bolt for each coil and tighten to 10 Nm (8 lb-ft). Reconnect the electrical connector to each coil until it clicks into place. Verify all four coils are secure and properly connected.
10. 10

    Perform visual inspection
    Inspect all vacuum hoses, PCV valve connections, and breather hoses for cracks, disconnections, or deterioration. Check serpentine belt for wear, cracking, or glazing. Inspect visible coolant hoses for leaks or swelling. Check engine oil level and condition. Look for any fluid leaks around valve cover, oil pan, and front of engine. Address any issues found before completing the tune-up.
11. 11

    Reinstall engine cover and clean up
    Align the engine cover rubber grommets with the mounting posts on the engine. Press down firmly on all corners until the cover snaps into place securely. Remove all tools and parts from the engine bay. Verify no tools or rags have been left behind.

Reassembly

1. Double-check all electrical connectors are fully seated and locked
2. Verify air filter housing is properly sealed with all clips engaged
3. Ensure engine cover is fully seated on all mounting grommets

Verification

• Start the engine and listen for smooth idle with no misfires or unusual noises
• Allow engine to reach operating temperature and verify idle remains smooth
• Check for any vacuum leaks by listening for hissing sounds around intake components
• Verify check engine light does not illuminate after test drive
• Perform a test drive to confirm smooth acceleration and no hesitation under load
• Scan for diagnostic trouble codes using an OBD-II scanner to ensure no issues are present

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