NASCAR driver Denny Hamlin is down but not out.

After finishing 39th due to engine failure this past Sunday at Auto Club Speedway in Southern California, Hamlin is sitting 21st in points. And that has him somewhat worried.

"At this point, it's starting to affect me," he said.

Hamlin qualified a season-best second at California, but at the halfway point in the 400-mile race, a faulty valve train caused the engine in his Toyota to expire and therefore led to his early departure in the event. Hamlin dropped four positions in the standings.

"It's frustrating because you want to do the best you can each week, and [crew chief] Mike [Ford] and the team did a great job setting up the car," Hamlin said. "We had a fast car. It doesn't matter in the end if you can't finish the way you're supposed to."

Joe Gibbs Racing personnel are scratching their heads at the team's shop in Huntersville, NC this week, trying to figure out why engine troubles have plagued them early in the season.

JGR has seen one of its drivers post a DNF due to engine trouble in three of the first five races this year. Joey Logano's motor quit on him at Phoenix last month, and Kyle Busch experienced the same problem the following race at his home track in Las Vegas.

The racing organization has also been forced to make several engine changes prior to a race this season, most recently with Logano at California. Logano qualified third, but had to start from the rear of the field after his team replaced the engine. He finished 25th.

"It's a big blow I'm sure to the organization and what we're doing with the engine shop and everything," Busch said after his third-place run on Sunday at California. "It's not that you'll find something and maybe get it fixed in a week, but certainly wish we would have been able to get it done by now. I know [JGR engine builder] Mark [Cronquist] is doing the best he can. The Toyota guys at TRD [Toyota Racing Development] are trying to figure out what's going on."

Other issues have also afflicted Hamlin's early-season efforts.

Last week at Bristol, Hamlin was caught up in an early-race accident. Hamlin suffered minimal damage but had to deal with an ill-handling car from there. He wound up 12 laps off the pace in 33rd.

"Bristol was obviously a missed opportunity for us," Hamlin said. "We never really got to show what we had at that race. It was just a few laps into the race where we got caught up in that incident. While it didn't look too bad from the TV, it really messed up things inside the car that we couldn't overcome. There was just not enough time."

His best finish so far this season is seventh, which came at Las Vegas.

Last year, Hamlin had his best season in NASCAR's top circuit, finishing second to Jimmie Johnson in the championship Chase. He ended the year 41 points behind Johnson, who captured his record-extending fifth straight title. Hamlin led the series with eight wins.

His 2010 season started on a rough note as well. After the fifth race of the year, Hamlin held the 19th spot in points and had yet to score a top-10 finish. Then the Virginia-native turned it around in the spring race at Martinsville. Hamlin won at Martinsville on the same day he was originally scheduled to have surgery on his torn ACL in his left knee. The race was delayed a day due to rain. He had the procedure two days after the win.

"The Martinsville spring race always seems to be the springboard for our season," Hamlin said. "Whenever we have struggles for the first five races or so, Martinsville is when we hit our momentum."

Hamlin figures to be at least one of the favorites to win at Martinsville this weekend. He has won the last three races on NASCAR's shortest track.

It's not time for Hamlin to flick the panic switch just yet, but things better get clicking soon if he wants to make the Chase for the sixth consecutive year.

"We definitely need to get some solid finishes, and we need to prove at this point that we can finish a race," he said.