"We don't know what happened — we were on the same strategy as (Truex)," Heroy said through a team spokeswoman. "We're going to go back to the shop and figure it out."
Montoya said the team possibly didn't get the tank full on his final stop, or that the fuel calculations were off based on a number of variables that could have included his pace while in traffic versus his pace in clean air.
"I think we missed it by a lap," he said.
Montoya has been inching closer to snapping his 101-race winless streak that dates back to Watkins Glen in 2010. After a rough start to the season that saw him stymied by mechanical failures and poor pit stops, he's rebounded and contended for wins on the ovals at Richmond and Dover.
The road course at Sonoma is always a place he's considered a contender, and he thought Sunday would be no different. At minimum, he said all weekend, was that his team would get a strong finish that would help him crack the top-20 in points.
"Effort don't give you points," he said. "We ran good and threw away a bunch of points again."