AVONDALE, Ariz. >> The credo in NASCAR has always been “If you ain’t cheatin’, you ain’t tryin’,” and that has never changed despite series effort to keep things on the up-and-up.

Now that culture has resurfaced again and at a most inopportune time for the beleaguered series.

There is one race to go to set the championship field, Sunday in Phoenix, and star driver Kevin Harvick has been snared in the latest scandal. NASCAR found Harvick had an illegal race-winning car — his second of the season — after his victory at Texas Motor Speedway earned him an automatic berth in the Nov. 18 title race in Florida.

The issue was with a spoiler that had been modified to give Harvick an aerodynamic advantage as he dominated and won for a Cup Series-high eighth time this season. Just how much of an advantage Harvick had is irrelevant: The levels of deceit NASCAR believes Stewart-Haas Racing went to were so devious the intent can’t be questioned.

Once NASCAR had the car back from Texas and in its Research and Development Center, the spoiler was removed and determined not to be the part supplied by the vendor. Instead, NASCAR believes SHR made its own spoiler, passed it off as one from the mandatory vendor and used it to help Harvick win.

The details were unveiled late Wednesday, 10 hours after Harvick’s spot in the finale was revoked. NASCAR has for several years refused to give specifics about infractions — keeping secret ideas on how to game the system — but reversed course on the Harvick penalty because of mounting criticism about the severity of his punishment. Not only did Harvick lose his spot in the final four at Homestead-Miami Speedway, but he must race the final two weeks of the season without his crew chief and car chief.

Scott Miller, NASCAR’s senior vice president of competition, said he felt SHR took the notion of pushing boundaries and exploring technology “into borderline ridiculous territory.”

With the stakes so high this weekend at Phoenix, where seven drivers will by vying for three open spots in the championship race, NASCAR will check spoilers at the track.

“It’s unfortunate that now we’ll be pulling spoilers off and having to do another inspection when the teams should really be bringing legal cars to the race track,” Miller said.

SHR has not challenged NASCAR’s cheating allegation. The team said it would not appeal the penalty and vice president of competition Greg Zipadelli said in a statement “NASCAR determined we ventured into an area not accommodated by its rule book.” The team has not made any members available for comment, and Harvick is not scheduled to speak to the media at Phoenix, where he is a nine-time winner. One of his victories came in the spring, part of a three-race winning streak marred by an illegal car at Las Vegas one week earlier.

The latest infraction raises questions about whether SHR has “ventured into an area not accommodated” by NASCAR’s rulebook with its other drivers. Its entire four-car lineup — Harvick, Kurt Busch, Clint Bowyer and Aric Almirola — is still eligible for the title race.

It wasn’t just SHR last weekend, either. NASCAR took three cars back to its R&D Center after Texas and all three failed teardown inspections. Ryan Blaney’s team was punished and so was the team for Erik Jones.

If the only three cars inspected failed, what about the other 37 cars in Sunday’s field?

“We certainly can’t bring the 40-car field back to R&D,” Miller said, elaborating on how issues get missed at the track. “We’re under time constraints at the race track to do these inspections. We have small windows and tight windows to get the inspections done, and we might spend in the neighborhood of five minutes with each of the 40 cars for the three-hour window that we have for inspection. To think that we can scrutinize a car as good in five minutes and we can in three hours at the R&D Center is a bit unrealistic.”

The last big scandal in NASCAR was in 2013, when Michael Waltrip Racing manipulated the finish of a race at Richmond to try to get Martin Truex Jr. into the playoffs. It led to a larger NASCAR investigation that uncovered at least one other case of race manipulation.

The latest scandal may be the tipping point for a revamped penalty system next season. Miller said the sanctioning body will look during the offseason at tougher penalties if a team that can’t even pass the first round of inspection.

“We realize that we kind of probably need to ramp up the severity of what goes on at the race track, and we’re hoping that we can change the culture to where we don’t have to play this cat-and-mouse game with the teams all the time,” Miller said.

What happens if a car fails inspection after winning the title? It wasn’t until Wednesday morning, long after Sunday’s race, that NASCAR revealed Harvick’s car had failed inspection.

Miller vowed intense scrutiny on the four championship-contending cars at Homestead, and said the post-race procedure is similar to the Daytona 500, where engines are examined at the track after the race.

“Knowing that so much is on the line, we can concentrate on those cars a little bit more than we can the 40-car field during the regular season,” Miller said. “So we’ll just ramp up the intensity of keeping people with eyes on those cars throughout the weekend and scrutinize those cars heavily, both before and after the race.”