1997 Nissan Sentra Owner's Manual - Page 141

AIR CLEANER HOUSING FILTER 5. Fit the new plugs, one at a time, into the spark plug socket and install them. Turn each plug in several full turns by hand, then tighten with a spark plug socket to the correct torque. Do not overtighten. Spark plug tightening torque: 14 to 22 ft-lb (20 to 29 N•m) 6. Holding the boot, reconnect each high tension cable to its proper spark plug by pushing it on until you feel a snap. 7. Reinstall all brackets as necessary. DI0205 ADI0631 SR20DE Engine Platinum-tipped spark plug It is not necessary to replace platinumtipped spark plugs as frequently as conventional type spark plugs because they last much longer. Follow the maintenance schedule, but do not reuse the spark plugs by cleaning or regapping. Blue rings on the ceramic portion indicate that the plugs are platinum-tipped. ● Always replace spark plugs with recommended or equivalent ones. 7-19 The air cleaner filter should not be cleaned and reused. Replace it according to the maintenance intervals shown in the ''Maintenance schedule'' section. When replacing the filter, wipe the inside of the air cleaner housing and the cover with a damp cloth. WARNING Operating the engine with the air cleaner off can cause you or others to be burned. The air cleaner not only cleans the air, it stops flame if the engine backfires. If it isn't there, and the engine backfires, you could be burned. Don't drive with it off, and be careful working on the engine with the air cleaner off.