In 1962, Pontiac introduced the Grand Prix -- a luxurious, high-performance car. Pontiac reduced the Grand Prix's size and converted it to a front-wheel-drive vehicle in 1988. The 2004 Grand Prix had two engine options available: a 200-horsepower, naturally aspirated 3.8-liter V-6 and a 260-horsepower, supercharged 3.8-liter V-6. When replacing the Grand Prix's spark plugs, it is important to check the gap on each spark plug, as an incorrect gap could cause a misfire or even engine damage.
Both of the 2004 Grand Prix's 3.8-liter engines -- supercharged and naturally aspirated -- use the same spark plug gap of 0.060 inches. There is a tolerance of 0.002 inches, meaning the gap may be 0.058 to 0.062 inches.
When replacing the spark plugs on the 2004 Grand Prix, it is imperative that you tighten them to 11 foot-pounds. Over-tightening the spark plugs could strip the cylinder head, resulting in a major repair. Too little torque may allow the spark plugs to come loose and fall out.
