The National Highway Traffic Safety Administration said Sunday that it was investigating consumer complaints about “sharp reductions” in acceleration on 2011 to 2013 Ford F-150 pickups that are equipped with the 3.5-liter EcoBoost V-6 engine.
The action, called a preliminary evaluation, covers about 400,000 of the F-150 pickups, the safety agency said. A Ford spokesman, Michael Levine ,wrote in an email that although the number of vehicles affected was likely to be more than 325,000, the agency’s figure was too high.
The F-150 is one of the automaker’s most popular, lucrative and thus important vehicles. And the twin-turbocharged EcoBoost V-6 is one of Ford’s main engines, used to power not just the F-150 but also sport utility vehicles like the Explorer, crossovers like the Flex and cars such as the Taurus.
A Ford spokeswoman, Kelli Felker, wrote in an email that the company was aware of the investigation and will cooperate with the safety agency.
The safety agency decided to investigate after receiving 95 complaints from F-150 owners saying they had experienced unexpected power loss during hard accelerations. About one-third of those complaints said the problem had occurred in damp or rainy conditions. There were no reports of accidents.
“Attempting to pass a vehicle accelerating from 55 miles per hour and truck either stutters or stalls,” one owner wrote to the agency in February 2012. “This almost caused a head-on collision. I am scared to pull out in traffic or pass anyone.”
The safety agency said Ford had sent three technical service bulletins to dealers telling them how to cope with “intermittent/stumble misfire on acceleration” in humid or damp conditions.
The EcoBoost is a family of engines in various sizes. Ford has widely promoted the EcoBoost’s turbocharging and direct-injection technology as providing excellent power as well as fuel economy.
The investigation covers only the 3.5 liter V-6, which made its debut in the F-150 for the 2011 model year. In 2012, about 43 percent of the F-150s were equipped with the optional 3.5 liter engine, Levine wrote in an email.
If investigators find additional reason for concern during the preliminary evaluation, it would be upgraded to an engineering analysis.
A preliminary evaluation does not typically result in a recall. That outcome is more likely — but not certain — with an engineering analysis.
Last July, Ford recalled about 11,500 of its 2013 Escape crossovers because of a fire hazard with its 1.6 liter EcoBoost four-cylinder engine.