Auto Service

How to Install Spark Plugs in a 1997 BMW 328i

1. Look on the underside of the 328i’s hood and find the emissions label. Find the spark plug gap listed on the emissions label. Check the gap on all six new NGK BKR6EK, or equivalent spark plugs, with a spark plug gap tool. If the gap is not within the specifications listed on the emissions label, exchange the spark plugs for new ones, as they are not adjustable.
2. Unscrew the engine oil cap and pull upward on the passenger’s side of the engine cover -- the one that reads “BMW” -- to remove it, exposing the ignition coils below it.
3. Pull outward on the retaining tabs on a coil pack and pull the wiring harness from the coil pack. Remove the four coil pack-retaining nuts with a ratchet and socket. If the coil pack you are working on has a ground strap attached to its mounting stud, make note of the wire’s position and pull the ground wire off the mounting stud -- only one coil has this wire. Pull the coil upward with a slight twisting motion to remove it.
4. Remove the spark plug with a ratchet, 6-inch extension and spark plug socket. Remove the spark plug from the spark plug socket. Press a new spark plug into the spark plug socket until the rubber insert inside the spark plug socket holds it in place. Hand-thread the spark plug into the engine with a 6-inch extension and a 6-inch socket.
5. Torque the spark plug to between 15 to 22 foot-pounds with a torque wrench, 6-inch extension and spark plug socket.
6. Line up the boot on the bottom of the coil pack with the top of the spark plug. Press the coil pack downward until you feel it click onto the spark plug. Press the coil pack wiring harness into the receptacle on the coil pack until the locking tabs click into place.
7. If the coil pack you are reinstalling had the coil ground wire attached, slide the ground wire onto the coil’s mounting stud. Hand-tighten the four coil pack nuts, then tighten them with a ratchet and socket.
8. Repeat Steps 3 through 7 to replace the remaining five spark plugs.
9. Line up the pins on the underside of the engine cover with the rubber mounts on the top of the engine, and set the cover on top of the engine. Tighten the oil cap to secure the cover in place.