The No. 18 and No. 20 Joe Gibbs Racing teams in the Nationwide Series likely will face big penalties after efforts to alter the results of a chassis dyno test.

NASCAR inspectors, preparing to do tests on horsepower numbers after a Nationwide race Saturday at Michigan International Speedway in Brooklyn, found magnets under the gas pedals on the two Gibbs Toyotas. Tony Stewart, making his final Nationwide start for the Gibbs team, finished third in the No. 20, and rookie Joey Logano, 18, was seventh in the No. 18. The race was won by Carl Edwards in a Ford.

Toyota has won 15 of 25 races this season in Nationwide, and all but one came in a Camry fielded by Gibbs. The exception was JGR driver Kyle Busch's victory at Charlotte in May in a car fielded by Braun Racing.

In the face of such domination, a month ago NASCAR ordered the Toyota Nationwide teams to use a smaller spacer to cut about 15 horsepower in their motors.

The incident Saturday was apparently an effort to keep the current numbers from looking too strong in the latest test.

"In our post-race inspection -- yesterday was the day we were going to chassis dyno cars -- our inspectors discovered some shims that were placed on the gas pedal stop," Robin Pemberton, vice president of competition for NASCAR, said yesterday. "The intention was to manipulate the numbers that we get when we get our information and data off the dyno."

Pemberton said NASCAR officials will meet today and tomorrow to determine what penalties will be handed out.

A racer died in an accident at the Grattan Raceway in northern Kent County, Mich. A television station reported about 2,000 spectators watched Saturday when Jack Drews, 72, lost control in a turn at 110 mph and crashed into an embankment. Drews, from western Illinois, was driving his 1961 Triumph when he drove off the track and crashed. His son was racing right behind him.