What would you do if your truck unexpectedly lost power while driving at high speeds? Some unlucky drivers of the 2012 Ford F-150 have had this happen, and they’ve been trying to fix this dangerous problem for years.

As a result, this is the No. 1 problem reported by F-150 drivers, according to CarComplaints.com. While it’s just one problem, it’s significant for a model year considered to be one of the truck’s worst.

What’s happening to these Ford F-150 trucks

The problem occurs without warning after a driver accelerates during highway driving. It’s an intermittent issue that seems to happen more frequently under damp or humid conditions. To make matters worse, vehicles traveling behind the F-150 have no warning that it’s losing power because the brake lights don’t go on. This requires drivers to quickly pull over to the shoulder in order to avoid an accident. 

At the center of this problem is the 2012 Ford F-150’s 3.5-liter EcoBoost V6 engine. It uses a combination of gasoline direct fuel injection and turbocharging which should ideally give the engine great fuel economy while producing plenty of power. But it seems as if Ford and its mechanics are having trouble sorting out the issue.

The F-150’s issue with direct fuel injection

Direct fuel injection works differently from indirect fuel injection because of its location. With the former, the fuel injector is mounted on the cylinder head. Fuel is shot directly into the combustion chamber, where the cylinders, pistons, and cylinder heads are located. By comparison, indirect or port fuel injection mounts fuel injectors in the manifold intake and fuel is sprayed at the back of the intake valves.

The main difficulty with direct fuel injection is that can cause excess carbon to build on the intake valves, which results in engine misfirings and loss of power. This sounds like it could be the F-150‘s problem, but there may be another cause.

Ford F-150’s EcoBoost trouble

Before the fuel is directly injected into the combustion chamber, the air that mixes with it must be cool so the engine to run efficiently. This is the job of the charge air cooler, which is the EcoBoost’s intercooler. It cools the engine after it’s sent through the turbocharger and before it enters the engine. 

For some drivers, the misfire occurred in damp or humid weather, and here’s where the problem lies. Under these conditions, condensation forms more easily in the intercooler, resulting in a misfire. 

Which component caused the problem and has Ford solved it?

Not quite. In the fall of 2012, Ford issued a technical service bulletin to address the misfire problem with specific attention to damp conditions. In it, Ford advised that the left catalytic converter be replaced if the truck’s computer showed a diagnostic code that indicated trouble with that part. If the diagnostic codes showed that cylinders misfired instead, then the bottom air deflector on the intercooler needed to be replaced.

Ford also warned that the F-150’s computer may show an engine misfire with no diagnostic codes. Without codes, mechanics would have to fall back on their troubleshooting skills. They would have to try duplicating the problem to determine which part would need a placement.

Judging from driver reports via Car Complaints, it seems like mechanics may not have seen Ford’s TSB. One attempted fix was replacing the throttle body that sits between the intercooler and engine. A bad throttle body commonly causes misfiring. Therefore it’s easy to understand why a mechanic might choose this solution — except it didn’t work. One driver wrote that her truck was on its fourth throttle body after repeated loss of power.

Some drivers said that dealerships suggested their trucks needed engine replacements, which would cost thousands of dollars. More drivers were told that the problem wasn’t repeatable and the mechanics weren’t sure about the problem. A couple of drivers knew what was causing the issue, even if the mechanics didn’t.

Although Ford issued a TSB for this problem, it may not have followed up with dealerships and mechanics to make sure they were prepared to handle the problem. And mechanics, for their part, tend to rely upon diagnostic codes to troubleshoot. But even if the F-150’s computer didn’t issue a code, a mechanic could still use the TSB as a starting point.

It’s not Ford’s first tangle with the complexities of direct fuel injection, as borne out with similar problems with the first-generation Escape in the early 2000s. So Ford has known about this issue for some time.

In 2018, the automaker reworked the EcoBoost engine into a hybrid system that uses both direct and indirect fuel injection that reduces carbon build-up. It makes us wonder whether a revisit of the turbocharger’s design might not be a bad idea. But it still doesn’t help the 2012 F-150 drivers who can’t get satisfaction from Ford about fixing this potentially unsafe vehicle.