BRISTOL, Tenn. -- Coming off a rare 40th-place finish, Jimmie Johnson said Hendrick Motorsports officials are still trying to determine what caused his team's engine issues a week earlier at Michigan International Speedway.
Johnson, a five-time NASCAR Sprint Cup Series champion and the series' points leader through 23 races, has finished 40th or worse only eight times since his debut in 2001.
"There is always concern," Johnson said prior to practice Friday at Bristol Motor Speedway. "We tested (this week) at Richmond and the guys were still asking me questions ? about what I felt and the order and how things went on and failed.
"They didn't have any clear direction then. And I'm not sure they've had a lot of time to work on everything with all four (Hendrick Motorsports) cars going to Richmond on Tuesday and Wednesday."
Engine issues haven't been a worry for the Hendrick organization this year, although teammate Dale Earnhardt Jr. was sidelined twice earlier in the year by problems under the hood.
"We definitely had one," Johnson said. "Our engine failed and the others didn't. In the past, that stuff usually boils down to a parts failure. And I'm assuming it was something in that department.
"Hopefully we can find out what batch it came from and which part is was. ? Hopefully we can narrow that down and get new parts and pieces in place so it doesn't happen to our car or anybody else's."
Of a more immediate concern for Johnson and the 48 team is this weekend's Irwin Tools Night Race at BMS. After stringing together four consecutive top-10 finishes at the 0.533-mile track nestled in northeast Tennessee, Johnson finished 22nd here this past spring.
With four wins (Daytona twice, Martinsville and Pocono) this season, and 15 top-10 finishes, Johnson and his team have had few missteps thus far. He has already clinched no worse than a Wild Card spot in this year's Chase for the NASCAR Sprint Cup.
And Bristol, while not being one of his best tracks, has been a place Johnson has often run well.
"We've been a top-five car here over the years," he said, "and hopefully we can take that next step and move into that top three. ? Running in the top three, you've got a great shot at a win.
"We'd like to win another race here. We've done it once ? and hopefully we can do it again."
Johnson was second fastest in Friday's opening two-hour practice. He has one career pole (2010) at BMS, in addition to his win.
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