The two Joe Gibbs Racing cars that have dominated the Nationwide Series this season likely will face stiff NASCAR sanctions after team members were caught deliberately trying to mask the horsepower in their powerful engines.

NASCAR inspectors found magnets under the gas pedals of the No. 18 and No. 20 Toyota's when the cars were sent to the chassis dyno following Saturday's race at Michigan International Speedway. Tony Stewart finished third in the No. 20 in his final Nationwide race for JGR, and Joey Logano was seventh in the No. 18.

The two cars have combined to win 14 of Toyota's 15 victories in 25 Nationwide races this season. To temper the domination, NASCAR last month ordered all Toyota teams to cut about 15 horsepower in their motors.