Parts for your 1998 Daihatsu Terios-Spark plugs

1998 Daihatsu Terios Spark Plugs — What They Do and How to Look After Them

Technical references such as the Daihatsu J100 Series workshop manual and OEM/aftermarket parts catalogues (including NGK and Denso listings) confirm that the 1998 Daihatsu Terios runs a 1.3‑litre petrol engine and is fitted with four spark plugs. Because it’s a spark‑ignition petrol, not a diesel, spark plugs are absolutely relevant on this model.

On a ’98 Terios, the spark plugs sit at the top of the cylinder head beneath the ignition leads/boots. Their job is simple but critical: each plug fires an electric spark to ignite the air–fuel mix, keeping the engine starting crisply, idling smoothly, and pulling cleanly on the open road. Healthy plugs help fuel economy and emissions, and they make the little Terios feel more lively around town and on gravel.

As part of regular servicing, it’s smart to inspect or replace the spark plugs at the intervals recommended in the service schedule. In real‑world Aussie and Kiwi conditions, standard nickel/copper plugs often suit 20,000–40,000 km change intervals, while platinum or iridium types can often go 60,000–100,000 km. If the vehicle sees lots of short trips, dusty roads, or towing, lean towards the shorter end. Always follow the workshop specifications for plug type, heat range, gap, and torque.

Common signs the Terios is ready for fresh plugs include harder starting on cold mornings, a rough idle, hesitation climbing hills, higher fuel use, or a check‑engine light for misfire. If a plug is removed for inspection, look for even light tan colouring, heavy soot, oil, or a worn centre electrode means it’s time.

• Replace all four plugs as a set and check the condition of leads/boots at the same time.
• Use a torque wrench and the factory torque spec to protect the alloy head, don’t overtighten.
• Avoid anti‑seize on modern nickel‑plated plug threads, it can distort torque readings.
• Confirm the specified gap in the manual or under‑bonnet label, don’t re‑gap fine‑wire iridium/platinum plugs.
• Apply a tiny dab of dielectric grease inside the boots to help future removal and keep moisture out.

Look after the plugs and the 1998 Terios will reward with easier starts, smoother running, and fewer surprises when heading off on a weekend mission.

Popular questions about 1998 Daihatsu Terios spark plugs

What spark plug type and gap should be used?
The correct plug type, heat range, and gap are specified by Daihatsu for the J100‑series Terios. Many owners choose OEM‑equivalent plugs from well‑known brands. Check the service manual or the under‑bonnet sticker for the exact spec and gap. If using fine‑wire iridium or platinum plugs, avoid adjusting the gap unless the manufacturer permits it.

How often should spark plugs be replaced on a 1998 Terios?
Service intervals depend on plug material and use. Conventional copper/nickel plugs typically suit 20,000–40,000 km, while long‑life platinum/iridium options can often run 60,000–100,000 km. If the Terios does lots of short trips or dusty work, inspect sooner. Always follow the factory schedule where available.

Can a home mechanic replace the plugs, or is a workshop better?
A capable DIYer can replace them with a plug socket, extension, and a torque wrench. Work on a cool engine, clean around the wells, and thread each plug by hand before torquing to spec. If any plug feels tight coming out, or a lead/boot looks perished, it’s safer to let a trusted workshop handle it to protect the alloy head.