1998 Pontiac Firebird Owner's Manual - Page 257

Be surethe posted octane premium is at least91 (at for least 89 for middle grade and for regular). If the 87 octane is less than 87, you may geta heavy knocking noise when you drive. it's bad enough, it can damage If your engine. If you're usingfuel rated at the recommended octane or higher and you hear heavy knocking, your engine needs service. Butdon't worry if you hear a little pinging noise when you're accelerating or driving uphill. a That's normal, and don't have to buya higher you octane fuel to get rid of pinging. It's the heavy, constant knock that means you have problem. a If your vehicleis certified to meet California Emission Standards (indicated on the underhood emission control label), it is designedto operate on fuels that meet California specifications. If such fuels are not available in states adopting California emissions standards, your vehicle will operate satisfactorily on fuels meeting federal specifications, but emission control system performance may be affected. The malfunction indicator lamp on your instrument panel may turnand/or on your vehicle may fail a smog-check test.If this occurs, return to your authorized Pontiac dealerfor diagnosis to determine the cause of failure. In the eventit is determined thatthe cause of the conditionis the typeof fuels used, repairs may not be covered your warranty. by Some gasolines thatare not reformulatedfor low emissions containan octane-enhancing additive called methylcyclopentadienyl manganese tricarbonyl (MMT); ask your service station operator whether not his fuel or contains MMT. General Motors does recommend the not use of such gasolines. If fuels containing " 'are used, ' I spark plug life may be reducedand your emission control system performance may be affected.The malfunction indicator lamp your instrument panel on may turn on. If this occurs, return to your authorized Pontiac dealerfor service. 6-4