According to the lawsuit, the 3.5-liter V-6 EcoBoost engine "contained serious latent design, manufacturing, or assembly defects" that cause vehicles to shake, misfire and rapidly lose power.
The problems often occur at highway speeds — putting the plaintiffs and fellow drivers in life-threatening situations, according to the suit.
Two of the plaintiffs, a married couple, claim their 2010 Ford Taurus SHO lost power and stalled several times. Another plaintiff says he lost power while accelerating his F-150 pickup.
The National Highway Traffic Safety Administration has received nearly 100 complaints about the engine, the lawsuit states.
The suit — filed Friday in U.S. District Court for the Southern District of Ohio Eastern Division in Columbus — was first reported by the Associated Press today.
Ford hasn't recalled any vehicles for the alleged defect, and NHTSA hasn't opened an investigation, AP said.
A Ford spokesman said the company was not prepared to comment because it has not reviewed the lawsuit in question.
According to the suit, the problems stem from a buildup of moisture in the engine's intercooler.
Acceleration results in more air flow through the intake tube, creating a vacuum that pulls in the air and moisture from the tube into the engine.
Ford knew of the problem, the suit says, because it published several technical service bulletins and suggested potential fixes to dealers covering the F-150.
According to the suit, owners weren't informed about the defects, which allegedly impact all vehicles with this engine. Autonews