JOLIET, Ill. – In the midst of its biggest credibility crisis since Dale Earnhardt’s death in 2001, NASCAR held a closed-door meeting with drivers and team executives on Saturday to outline rules changes it hopes will help better define what is and is not allowable during a race and restore the public’s faith in the sport.

On the eve of NASCAR’s playoff opener at Chicagoland Speedway, drivers woke up Saturday morning and still did not know what is legal and what is not in terms of helping another car during a race after the fallout from last week’s controversial finish at Richmond International Raceway.

They may have a better idea now.

NASCAR officials, led by chief executive officer Brian France and President Mike Helton, ordered the drivers to run all-out in hopes of getting a good finish.

“Run 100 percent all the time, and you don’t have to worry about it,” driver Michael McDowell told USA TODAY Sports after the meeting. “That was the gist of it. They said, ‘There are lots of things that happen during the race where you have to save fuel or save your stuff. We get that. We’re not looking to hammer anybody. Just race 100 percent. Don’t mess with the finish.’”

But the finish was messed with one week ago, when the Chase for the Sprint Cup 12-driver field was supposed to be set in the season’s 26th and final regular-season event.

A suspiciously-timed spin by Clint Bowyer with seven laps remaining set off a sequence of events that has crippled NASCAR’s public image.

Bowyer and Michael Waltrip Racing teammate Brian Vickers were found to have given up spots under team orders so that another driver, Penske Racing’s Joey Logano, would make the top 10 of the points standings. By doing so, Logano did not need to use one of two wild card entries for the Chase – and MWR driver Martin Truex Jr. got it instead.

NASCAR reviewed in-race radio chatter and video and determined the fix was in at MWR. NASCAR levied the largest penalty in the sport’s history – it docked all three MWR drivers 50 points, fined MWR $300,000, put team general manager Ty Norris on probation and removed Truex Jr. from the field, replacing him with Ryan Newman.

As the week went on, more questionable radio chatter emerged between Penske and Front Row Motorsports. NASCAR reacted Friday by giving Jeff Gordon – a victim of the chicanery – an unprecedented 13th spot in the Chase.

To prevent similar actions during the Chase, though, NASCAR decided to implement immediate changes to its rulebook with a Saturday afternoon technical bulletin to teams.

Among the changes:

A new rule will require drivers to race “at 100 percent of their ability with the goal of achieving their best possible finishing position in an event.” That means no more deal-making, giving up a position for a teammate or “artificially altering” the finish of a race. Any driver or team engaging in such behavior – which could include intentional cautions or pulling off the track to give an advantage to another competitor – is subject to penalty.

Digital radios may no longer be used on the spotters’ stand. Spotters have communicated on a private channel with the team and crew chief – outside of the driver and public’s earshot – in addition to the analog radio any fan can hear on a personal scanner. That led to deals being orchestrated from high above the track; those can no longer be done in secret.

Only one spotter per car can be present on the spotters’ stand. This affects teams such as Penske Racing, whose team owner Roger Penske has been a frequent presence alongside the spotters. To help enforce the policy, NASCAR is installing a camera on every roof.

NASCAR will make a change to its restart rules, which will be announced during Sunday’s pre-race drivers meeting.

“I think we wanted it to be very clear, and we wanted to reinforce the cornerstone of NASCAR, which is giving your all,” France said. “The extent that other factors got in the way of that, we want to eliminate those factors and deal with it going forward.

“This is what they (the drivers) want. They don’t like team rules and they don’t like some of the things that have gone on in the past.”

During the 17-minute private meeting – media was kept 100 yards away from the door by security personnel – France was said to be very angry in telling the drivers how they had damaged NASCAR’s credibility. He read samples from news coverage of the Richmond fallout.

“Circumstances happened that are unhelpful in the credibility category. There’s no doubt about that,” France said after Saturday’s meeting.

Drivers were allowed to ask questions during the meeting – for example: is pushing a teammate to the win at Talladega Superspeedway, one of the Chase tracks, still legal? – and most left quickly afterward via golf cart without comment.

Front Row Motorsports driver David Ragan said NASCAR would more clearly define the “dos and don’ts” going forward.

“They’re going to pay attention to how races can be manipulated when maybe they didn’t focus on that in years past,” he told USA TODAY Sports. “I think we already knew (what not to do), but they’re just going to watch it a little closer.”

McDowell said he was pleased with the outcome of the meeting because the amount of variables that happen during a race make rules enforcement “a moving target.”

“I wouldn’t want to be on their side of the fence either,” he said. “There are a lot of things that are going on and it’s hard to make judgment calls by the seat of your pants right there. In racing, it’s hard to define clear lines.”

Crew chief Paul Wolfe, who guides the No. 2 Ford of reigning Cup champion Brad Keselowski, said, “I think everyone should have a pretty clear understanding of what that (line) is now.

“If you go out there and run 100 percent to your ability and run a normal race, then everything will be fine.”

Seven-time NASCAR champion Richard Petty, who co-owns Richard Petty Motorsports, said NASCAR “didn’t come with nothing new.”

“They didn’t change any rules or anything,” he said. “They just said, ‘Do what’s right and everything will work out OK.’ Everybody knows what’s right. And sometimes, we don’t do what’s right.”

Helton said Saturday marked “Day 1 of this phase of NASCAR” and said it was the responsibility of the garage to provide better regulation for the fans.

Added France: “My hope is we’ll have greater clarity and we’ll have that line as bright as possible because we’re about delivering for our fans what they expect – and that’s the best racing.”

Chris Jenkins contributed to this report. © 2013 USA TODAY. All rights reserved.

Chase for the Sprint Cup

Championship Field

1. Matt Kenseth, 2,015.

2. Jimmie Johnson, 2,012.

3. Kyle Busch, 2,012.

4. Kevin Harvick, 2,006.

5. Carl Edwards, 2,006.

6. Joey Logano, 2,003.

7. Greg Biffle, 2,003.

8. Clint Bowyer, 2,000.

9. Dale Earnhardt Jr., 2,000.

10. Kurt Busch, 2,000.

11. Kasey Kahne, 2,000.

12. Ryan Newman, 2,000.

13. Jeff Gordon, 2,000.

Associated Press