Why do i have spark knock in my 2004 Pontiac grand prix with v6 engine and can you use octane booster the car has 18000 miles?

Answer 1

Adding octane booster, or using higher octane fuel, will not hurt your car. Octane is actually a combustion inhibitor, not an accelerant. If your engine is truly knocking, it's because the fuel/air mixture, during the compression stroke, is igniting before the spark plug is expected to fire. (The fuel/air mixture, under compression, should not "explode" before your distributor sends the "Voltage" needed to make the spark plug fire. This should only happen at the very end of the compression stroke.) Adding higher octane fuel will prevent the fuel from igniting under compression, allowing the compression cycle to complete its phase to completion. Higher octane fuel also burns slower, so it may even smooth-out your idle. Either way, your car should be fine - Just make sure your plugs are gapped properly, and knocking is really the problem - The best bet is to just go up one octane level at the pump. If the problem goes away, stay with that grade fuel. If not, go up to premium - And check again. (If your vehicle is designed for 87 octane fuel and you need to burn 91 octane fuel to stop knocking, I'd seriously consider having a mechanic diagnoe the problem.)