Ford TSB Warns Of Modifications To 2011-2012 5.0 Mustangs

Ford has tidal waves throughout the Mustang modding realm this week, issuing a new Technical Service Bulletin (TSB) to dealers that essentially says, “If an owner has modified their 2011-2012 Mustang 5.0 drivetrain, their warranty is void”.

TSB 11-7-7 warns Ford Service Departments that when servicing 2011-2012 Mustangs with the new 5.0 liter engine, to look for modifications the owner may have made before covering a list of engine and drivetrain failures.

The new 5.0 liter 32V DOHC Coyote engine has been widely received as one of the best new engines Ford has ever produced. But what a lot of shade tree mechanics don’t know or overlook is that this high compression engine is near maxed out structurally at is factory specified power output.

The TSB warms that common modifications done by a lot of owners that increase the power output can cause premature failure of not only a number of engine components, but drivetrain systems like clutch and gears.

Ford has been in the business of encouraging its owners to customize their cars in the past decade, in fact even offering a raft of products though their dealers to do just that. But the company is sending out a warning shot that they will be voiding warranties if it is determined that modifications made by the owner are the cause of failures.


In the TSB it outlines a number of common modifications that can cause engine and drivetrain failures:

• Custom PCM Software Calibrations

• Air induction system (air box, air filter, zip tube)

• Super chargers

• Nitrous oxide systems

• Throttle bodies

• Exhaust air path/system

The TSB outlines potential damage line items that can be caused by the above modifications:

• Excessive Cylinder Pressure And Temperature

• Piston damage

• Spark over-advanced (knock-induced damage)

• Insufficient enrichment

• Catalyst damage

• Piston damage

• Connecting rod damage

• Oil pump damage • Catalyst damage

• Clutch damage

• Piston and/or ring damage due to improper knock

The figure below shows the decision path that technicians are to take when diagnosing problems with  a car. If you follow along, the end result is cancelation of the warranty if it is deemed that damage or failures are caused by any number of modifications listed above.

What this means people is that Ford has given their dealers the legal green light to begin blackballing Mustang owners for modifying their cars. So if you are an owner of a 2011-2012 Mustang with a 5.0 liter engine and have been loading it up with custom tunes and other aftermarket power adders be aware. You might think twice about heading down to your local dealership complaining about your broken clutch or rough idle.

While this TSB is a bit unsettling, the rules have not changed. Modding your Mustang from a powertrain standpoint has always carried with it some inherent risks. The new 5.0 engine is one of Ford’s best but people need to learn that with its high compression, it is already tuned to top capacity from the factory when it comes to reliability. Mod with care.

About the author

Sam Haymart

Publisher and editor of Steed Publications news outlets including this one, ActivityVehicle.com, Motoring2.com, and others. He is host at TestDriven.TV and has been an auto journalist since 1994.