NHTSA Preliminary Evaluation PE13018

On May 22, 2013, the Office of Defects Investigation (ODI) opened PE13-018 to investigate 95 complaints alleging incidents of reduced engine power during hard accelerations in model year (MY) 2011 through 2013 Ford F-150 trucks.ODI was aware of three technical service bulletins (TSBs) issued by Ford for a condition that was related to moisture accumulation in the Charge Air Cooler (CAC) for the turbochargers.A Preliminary Evaluation was opened to gather information to assess whether the subject vehicles contain a safety related defect.The subject vehicles are powered by Ford?s 3.5L EcoBoost engine which uses twin turbochargers to obtain a balance of fuel economy and engine power based on the driver?s demand.When the driver requests more power from the engine, as in accelerating to pass, merge, ascend hills or haul a load the two turbochargers will spin up compressing the air which is then used to increase the power created by the combustion in the engine.The compressed air, which gains heat by the compression process, is passed through a Charge Air Cooler (CAC) which is designed to lower the temperature of the air in order to make the combustion process even more efficient (Figures 1 and 2).In response to ODI?s Information Request letter, Ford indicated that a misfire condition could occur after steady-speed operation under significantly humid and rainy conditions.Ford?s analysis found that under those conditions, condensation could form and accumulate on the inside of the CAC tubes which could then be ingested into the engine during particularly hard acceleration near wide-open throttle.An engine misfire of up to three cylinders could occur if the amount of condensed water released from the CAC exceeded the engine?s operating threshold for water ingestion.Ford noted that due to regulations set by the EPA, the powertrain software would disable up to two of the misfiring cylinders for no more than 30 seconds and until the driver tips out the throttle in order to prot