The 2003 Honda Civic EX was available as either a coupe or sedan. Both versions of the Civic EX came fitted with a 1.7-liter four-cylinder engine that produced 127 horsepower. Honda fitted the Civic with a distributorless ignition system. This system has four coil packs; each pack sits on top of a spark plug and provides the electric current needed to create a spark. Tuning the 2003 Civic EX involves replacing the spark plugs, as well as checking the air filter and fluid levels. Honda recommends replacing the spark plugs every 110,000 miles and replacing the air filter every 15,000 miles.
Measure the gap between the center and ground electrodes on all four new NGK PZFR6F-11 (or equivalent) spark plugs, using a spark plug gap tool. The 2003 Civic EX requires a gap of 0.039 to 0.043 inches. If any new plug does not measure within this range, do not adjust the gap. Exchange incorrectly gapped plugs for new ones.
Loosen the plastic screws securing the engine cover to the top of the engine, using a flat-head screwdriver. Pull the coil cover from the engine.
Unplug the wiring harness from the top of one coil pack by pressing the locking button and pulling the harness from the coil.
Remove the nut holding the ignition coil pack to the engine, using a ratchet and socket, and pull the coil pack upward with a slight twisting motion.
Remove the spark plug below the coil, using a ratchet, 6-inch extension and a spark plug socket. Remove the old spark plug from the spark plug socket and insert a new spark plug.
Hand-tighten the new spark plug into the engine, using a 6-inch extension and spark plug socket. Connect a torque wrench to the 6-inch extension and tighten the spark plug to 13 foot-pounds.
Set the coil pack on top of the spark plug and press the pack toward the spark plug until you feel it "click" into place. Tighten the coil pack nut to 8 to 9 foot-pounds, using a torque wrench and socket. Plug the wiring harness into the coil pack; listen for it to click into place.
Repeat steps 3 through 7 for the remaining three spark plugs.
Set the coil pack cover back on top of the engine and tighten the nuts, using a ratchet and socket.
Remove the seven bolts securing the air filter cover on the rear of the engine compartment, using a ratchet and socket or a Phillips screwdriver. Pull this cover up and out off the vehicle, exposing the air filter below it.
Grab the air filter and pull it from the air-filter box. Blow the debris inside air filter out with compressed air. Hold the paper element part of the filter towards sunlight. If sunlight passes through the paper element, reuse the air filter. If little or no sunlight is visible, replace the filter with a new one.
Install the new or old air filter into the air-filter box. Reinstall the air filter cover and tighten the bolts with a ratchet and socket or a Phillips screwdriver.
Check the Civic's fluid levels, including: transmission fluid, coolant, engine oil, power steering fluid, brake fluid and clutch fluid.
