NOTE: Always follow your vehicle's maintenance schedule for spark plug replacement.
Before you begin:
- Ensure you have the correct spark plugs recommended by the vehicle manufacturer or specified by NGK.
- Allow the engine to cool down before starting the work.
- Ensure you have the necessary tools and equipment such as spark plug wrench, socket wrench, extensions, and spark plug gap tool (if needed).
Step 1: Prepare and Access
- Open the hood of your Supra and safely prop it open.
- Remove the engine cover (if equipped) to gain access to the spark plug area.
Step 2: Disconnect Battery Cable
- To prevent electrical shocks and accidental engine start, disconnect the negative (black) battery cable from the battery terminal.
Step 3: Remove Spark Plug Wire(s)
- Using a spark plug wire puller (recommended) or with your hands, gently pull one of the spark plug wires from its spark plug.
- Take note of the firing order or placement of each wire for reinstallation in the same order.
Step 4: Remove Old Spark Plug
- Use the appropriate size socket wrench and extension to loosen and remove the old spark plug.
- Be careful not to drop the old spark plug into the cylinder head.
Step 5: Check and Gap New Spark Plugs
- Inspect the old spark plug for any signs of wear, deposits, or damage. Compare it to the new spark plug.
- If necessary, use a spark plug gap tool (refer to your vehicle's specifications for the correct gap) to adjust the gap of the new spark plugs.
Step 6: Install New Spark Plugs
- Hand-tighten the new spark plugs into their respective cylinder heads.
- Hand-tightening helps to avoid cross-threading and allows you to feel when the spark plug is seated correctly.
- Once finger tight, use the socket wrench and extension to firmly tighten the spark plugs.
- Do not overtighten.
Step 7: Reinstall Spark Plug Wire(s)
- Reconnect the spark plug wires to the corresponding spark plugs.
- Ensure they are securely attached.
Step 8: Reconnect Battery Cable
- Reconnect the negative (black) battery cable to the battery terminal.
Step 9: Test Drive
- Start the engine and let it run for a few minutes.
- If your vehicle runs smoothly without any misfires or rough idling, you have successfully replaced the spark plugs.
Remember:
- Always follow the maintenance schedule recommended by Toyota for spark plug replacement intervals.
- If you encounter difficulties or have concerns during the process, it's best to consult a professional mechanic.
