Tony Stewart insists he does not have a problem with Dale Earnhardt Jr. He does, however, have a problem with NASCAR's new rules package concerning its race cars.

NASCAR.com reported that Stewart, who is coming off a 19th-place finish at the Geico 500 at Talladega Superspeedway, admitted that he still is having difficulty with NASCAR's decision to reduce the horsepower in the cars from 850 to 725 - while increasing the downforce.

Tony Stewart curse Dale Earnhardt Jr. after bumping cars leads to Stewart spinout at Richmond

"It's like I'm in the middle of a calculus equation, and I didn't take pre-calculus,'' Stewart said. "I'm working on it."

But positive results obviously have been slow to develop. In 10 starts so far through 2015, Stewart has zero wins, just one top-10 finish and has led for a grand total of 14 laps. He has five finishes of 30th or worse and is 30th in the Chase for the Cup standings.

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Stewart finished sixth at the Food City 500 in Support of Steve Byrne and Stand Up To Cancer on April 19 and was running strong the following week at the Toyota Owners 400 in Richmond when he bumped cars with Earnhardt, spun out and was unable to restart his car. Stewart finished 41st.

In frustration of having his momentum halted, Stewart was recorded cursing Earnhardt after the collision and later throwing his helmet and HANS device into the back of his team's race hauler.

Stewart, however, insisted his ire was not directed at Junior.

"That wasn't frustration at Dale Jr.," he said. "That was frustration that we haven't had many days where we were running as well as we were that day. ... and then to have it end up like that. Junior and I are friends. We're fine."

Beyondtheflag.com suggested ways for Stewart to fix his season, saying that he should have been able to adjust his race for the lower horsepower by now and that the problem could be with crew chief Chad Johnston.

Stewart, however, defended Johnston's performance during the driver's subpar season so far.

"Chad isn't getting the results he deserves,'' Stewart said.