The federal government and Ford Motor are probing partial engine failures on some 725,000 recent-model vehicles that could cut engine power, often at highway speed.
Affected: 2009 through 2011 models of Ford Escape and Mercury Mariner SUVs and Ford Fusion and Mercury Milan sedans.
The National Highway Traffic Safety Administration and Ford report nearly 1,500 complaints that appear related to the problem; three crashes were involved and one person was hurt. No deaths have been reported.
The engines aren't the EcoBoost engines that have had fire problems in newer models. But, coming not long after those failures, the new investigation is sure to continue clouding Ford's image.
The government says it began taking a closer look at the vehicles last year after a request from the North Carolina Consumers Council.
NHTSA says the engines in this case don't quit running, but, apparently because of a flaw in the throttle-body system, the engines erroneously shift into the reduced-power "limp-home" mode. The sudden cut in power can feel to a driver as if the engine stalled, NHTSA notes.
Many vehicles have such "limp-home" settings. If the engine computer senses a problem, it cuts power to avoid ruining the engine or related components, but leaves just enough power to, as the name suggests, limp the vehicle home or to a service shop at greatly reduced speed -- about 20 mph in this case.
Throttle body systems meter how much air goes into the engine. The ones in question were made by Delphi, NHTSA says, and both it and Ford issued technical service bulletins (TSB) in 2009 describing to dealers how to fix the problem.
Ford and Delphi considered the problem fixed, but NHTSA continued getting complaints, including on 2010 and 2011 models, and "the complaints show an apparent increasing trend," the agency says.
An example from NHTSA files:
The owner of a 2011 Fusion told the agency last September that the car failed after the dealer performed the TSB suggested fix in 2009, and later replaced the entire throttle body.
NHTSA's probe is a preliminary evaluation, the lowest-level investigation. It can upgrade that to an engineering analysis if it finds enough evidence to suggest the matter needs further study.
The final step is a recall. Most of those are done by the automaker, rather than ordered by NHTSA -- though often under the threat of a NHTSA recall order if the car company doesn't "voluntarily" recall the vehicles for free repairs.