Ford 5.4L Triton Common Problems in Trucks
- Last Modified : Mar 30, 2021
There are many people who are looking at buying a used truck (New to them!) or considering keeping their old truck for a few more years. Everyone sees these late model F150's with the 5.4L Triton engine as a risky investment but I'm here to tell you this engine can be solid. It does have common reoccurring problems you should be aware of. These problems range from easy to change coils, to the dreaded spark plug, all the way to the scary and expensive timing chain issues.
This article is written with the 5.4L 3v Triton truck engine in mind, but it also applies to the 4.6L used in trucks, vans, and cars.
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5.4L Triton Ignition Coils
The most common thing we need to mention, but it is the easiest to fix, is the ignition system. The 5.4L Triton features a coil-on-plug (COP) design; a separate coil for each cylinder that sits atop a specialized spark plug (more on that adventure in a minute!). COP systems are now very commonplace in the automotive industry. The general consensus is that this type of ignition system is the most efficient design offering independent control, but the coils do suffer from failures likely related to heat. Most trucks will need multiple replacements in it's lifetime.
Most of the coil failures are actually because of the coil boot, the piece of rubber that covers the spring that touches the prong to the spark plug. These deteriorate with age and weak spots in the rubber can cause the spark to jump to the cylinder head instead of the spark plug. The spark plug wells can also fill up with oil or coolant from nearby leaks causing the spark to short to the cylinder head. The ignition coil do fail internally as well. Symptoms of a failing ignition coil is cylinder misfires under load, accelerating, or most notably cruising up a small grade at arond 55mph in overdrive. It will cause a light jerk or bucking that some describe as a transmission issue. The ignition coils easy to replace though. Generally we diagnose the cylinders with the misfire and replace the spark plug and ignition coil for those cylinders. Avoid cheap aftermarket coils, only use Motorcraft DG511.
5.4L Triton Spark Plugs
Spark plugs are a whole different animal on this engine. Each of these sensitive coils are placed upon a specialized spark plug that tends to break when removed. Due to the design of the combustion cylinder the plugs needed to protrude down through the head to the combustion chamber. The situation is slightly ironic since earlier 2 valve 5.4L (97-03) tended to blow spark plugs out of the head but later 3 valve 5.4L (04-07) tended to break off in the head.
These plugs generally last around 100k miles but they are a bear to remove when you do go to replace them. They have extended sleeves that reside down inside the head that tend to break off because of possible carbon/rust build up. This issue was fixed with an updated spark plug. SP546 is the revised spark plug, the SP515 is the old one. More details are available in another article I wrote which include step by step instructions on Replacing the spark plugs on the 5.4L Triton at home. 2008+ Engines use a different design that does not break.
5.4L 3v Catalytic Converters
Be wary of driving with this engine if you are experiencing a misfire of any kind. Some people ignore the misfire. At the dealer, we generally see these trucks go a long time with this misfire condition. Eventually, the truck will start to backfire through the intake and even fail to accelerate to over 30mph in severe cases. If this happens, likely you have a catalytic converter that has been damaged due to misfires. Always be on the lookout if you have a converter failure because engine drivability issues kill catalytic converters.
A lesser, more annoying, issue you might get is a exhaust rattle when idling or accelerating. This could be caused by damaged honeycomb inside of the catalytic converter. On these older vehicles I just recommend some aftermarket replacements.
5.4L 3V Fuel Pump Driver
As this model ages, a very common issue in these trucks equipped with a 5.4L Triton 3 valve engine is a failure of the fuel pump driver module. This specific vehicle platform uses a module to control fuel line pressure by pulse width modulation of the fuel pump. The fuel pump driver module is located under the vehicle exposed to the elements. Specifically, on a F150, it is located above the spare tire attached to the frame. Originally Ford attached the aluminum driver module directly in contact with the steel frame. This led to extreme corrosion build up on the module.
With extended time the corrosion would eat a hole through the aluminum housing and expose the electronics to water and road grime. The module will short out temporarily causing drive-ability issues and eventually could cause permanent damage to the smart junction box. This usually causes the dreaded code P1233 Fuel pump Driver Module (FDM) Offline. Ford later released an updated replacement fuel pump driver module that comes with mounting studs to space the module away from the frame slightly. The most common symptoms, aside from a no start, is lack of power, the code P1233, and hard starting.
Fuel pumps can go bad, but we just don't see them that often. If you have an issue of insufficent fuel pressure, my bet is on the driver module or the wiring leading to it.
5.4L 3v Variable Timing Chain Issues
Lastly, the scariest part for most late model 5.4L Triton owners, is the problems related to the timing chain, tensioners, and the variable valve timing. When you hear a 3 valve 5.4L Triton running, you generally can tell by the sound of the engine. Especially on light acceleration most noticeable to the driver with the window down while pulling forward in a drive or down an alley.
Most of these issues are caused by low oil pressure do to pump failure or lack of following service intervals, but phasers and tensioners can fail from age as well. As this problem progressively gets worse, when engine is hot and you let off the throttle the engine may loose the ability to maintain engine timing causing it to run rough and rattle like crazy. Sometimes the rattle will go away within a few seconds, sometimes it will not go away until you rev the truck up. The base problem usually being low oil pressure when hot.
Eventually the timing guides will fail from the chain slapping around. It's all down hill from there. That leads to an out of time engine with valve damage and metal particles throughout the engine. This system is fairly complicated so check out the full description an operation of the Ford 5.4L Variable Cam Timing. I also wrote a guide to replacement of all these components in another article Changing Ford 5.4L Phasers and Timing Chain.
One thing that has picked up in popularity is deleting the VCT all together. A link I provided in the paragraph above explains how the system works, and it is very easy to eliminate the VCT. You should check out Tuning the 5.4L 3V.