Updated

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

NASCAR inspectors, preparing to do tests on horsepower numbers following Saturday's Nationwide race at Michigan International Speedway, found magnets under the gas pedals on the two Gibbs Toyotas.

Tony Stewart, making his last Nationwide start for the Gibbs team, finished third in the No. 20, and 18-year-old rookie Joey Logano 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, last month 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 Sunday. "It was magnets that were about a quarter-inch thick that prevented the accelerator from going 100 percent wide open.

"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 Monday and Tuesday to determine what penalties will be handed out.

"I anticipate that we haven't seen the end of it yet," Pemberton said when asked if the penalties were likely to be severe. "We historically don't make our decisions within a 24-hour period. It takes time to get everybody in a group and talk about it."

J.D. Gibbs, son of owner Joe Gibbs and president of the team, said JGR takes full responsibility for the actions of its employees.

"Let me just say that, first and foremost, that that was a really poor, foolish decision on the part of our key guys there at JGR," Gibbs said. "I want to apologize to NASCAR, to our partners, to Toyota guys. A couple guys chose to make a decision there that really impacts all of us."

Gibbs said he was thankful that it was an off-track incident that did not involve racing and added that the big — and most frustrating — question is why was it done?

"I know they were probably frustrated from the standpoint that wanting to show that, 'Hey, we have less horsepower than ever before' and they wanted to make it look like we're handicapped even more than we actually were," Gibbs said. "I understand that, but that's not an excuse.

"For us, we kind of feel like, in the engine shop that's kind of a badge of honor. You win that engine dyno, good for you. That's kind of how we felt in the past few years and [chief engine builder] Mark Cronquist and those guys really feel like they want to win that thing.

"The way I look at it, to come back after you've been chopped, to come back and win it again, that's awesome," Gibbs noted. "That's a great story. That wasn't able to be told."

He said no matter what action NASCAR takes, the team will address the situation in-house.

"[We'll] figure out exactly what happened and those that were responsible," Gibbs said. "There's going to be punishment for that. That's just part of life. You can't do that."

In a statement released by the elder Gibbs, he echoed his son.

"If this alleged incident proves true, it goes against everything we stand for as an organization," the former Washington Redskins coach said. "We will take full responsibility and accept any penalties NASCAR levies against us."

Lee White, president of Toyota Racing Development, said the company is grateful that the team stepped up and took responsibility and made it clear Toyota was not involved.

"I found out about it halfway through the day session last night, when I went over there to see what was going on," White said. "I was surprised to see what was happening, and astonished and frankly incredulous. I couldn't believe it was happening because it's clearly defined in the entry forms that you don't do this sort of thing.

"But I'm sure Joe and J.D. will take care of that internally and, whatever fans think, they're going to think. We're just going to keep working on our stuff."

Pat Suhy, GM Racing group manager for NASCAR, said the actions by the Gibbs team raise more questions.

"It's not something that you like to hear about and you have to just question every chassis dyno that's ever been run on every Toyota," Suhy said. "You look at the [No.] 32 car [of Brian Vickers and Red Bull Racing], the 32 and the 18 and the 20 made about the same power the first run [on the dyno]. When they took the magnet, or whatever this device was, out of the 18 and the 20, they both came up.

"What I don't know is if it's a Toyota problem, if it's a Joe Gibbs thing, how widespread is it and how long has it been going on, because a lot of what's been done [by NASCAR] has been based on the chassis dyno results. And, if they were always showing worse on the chassis dyno than actual, maybe [NASCAR] didn't go far enough.

"It's disappointing to hear that anybody, whether it's a manufacturer or a team or an individual on a team would go to any length to do that," Suhy added. "It's bad for the entire garage, I think."

Jack Roush, co-owner of Roush-Fenway Racing, which fields Fords in the Nationwide Series, called the Gibbs team's actions "extremely detrimental to stock car racing.

"NASCAR will figure out what they should," Roush said. "If they're going to make decisions based on parity, after they've given [Toyota] what they've given them with regard to parameters on their engine, based on flawed data that a team or the manufacturer, one of the other, had kited or shaved, that certainly is detrimental to my interests."