5.4 triton vs the 3.5 Ecoboost?

Hi! I am new here and am the proud owner of a 2005 Ford Expedition with 237K on her.
I have a question and this would usually be something I would have asked my dad but unfortunately he passed in 2019 so that’s not possible. He was a Lincoln/Mercury/Ford technician for over 30 years so definitely my go to for things like this. We both actually referred to this forum and the Ford enthusiasts forum bc me, him and mom all have Expeditions. Mine is the oldest lol and has the most miles.
Now I’m sure no one needed to hear my life story but that’s a little background as to why I’m here.
I’m currently looking at getting a newer model, specifically looking at a 2017 with less than 100k, one owner, all the bells and whistles.
I hate to sound stupid but what is the difference in the 5.4 triton in mine vs this 3.5 ecoboost? Is it a good engine? I’m very diligent about my oil changes and servicing so that’s not an issue.
I’m sorry again for sounding like an idiot but I need help. I tried asking around a little and that was useless. Even tried AI and well, I need real folks with the same mindset as I do. Thank you in advance.

Welcome to the forum. This same question has been discussed a number of times. Here are some links.

5.4 vs 3.5

3.5 compared to 5.4

Hey there! Thank you! I honestly appreciate it. I couldn’t find this info to save my life so it is incredibly helpful. Thank you again

I have owed both, a 2013 with the 5.4, and now a 2017 with the 3.5 Ecoboost. I have towed my 7,000 lb travel trailer with both and found the 3.5 to be a much more powerful engine. My 5.4 had a well documented problem with the cam phasers and the timing chain. I was looking at replacing the engine, but choose to go to the 3.5 instead. Turbo charged engine have a number of different areas that need to be watched carefully. If managed correctly and regularly you won't have any problems. I put 100K on my since I bought it and its still going strong. I upgraded the thermostate to help keep the operating engine temp down (which is extremely important with a turbo charger). I also added a catch can on the PCV side to help reduce cylinder build up.

early ecoboost 3.5's have a cam phaser issue. They didn't redesign the phasers until circa 2022 or 2023, so even if the phasers were replaced before the new ones were introduced, you're likely to have to do it again. Its a very expensive job, I just did it to my 2019, done by a quality independent shop it was around $6000.

the ecoboost got a fairly major re-engineering circa 2018 which added an additional manifold injector to help clean the intake valves.

the EB35 gets way better gas mileage than the V8's, I get around 20 MPG cruising on the highway, and maybe 15 towing a ~5000 lb camper if I keep my speed down. and gobs of torque from just above idle to as fast as you wanna go.

I believe your 2003 Expedition has the original 2V version of the 5.4 modular, I had one of those in a 2001 E150 van, the engine was great, but that van went through 3 transmissions in 20K miles.... skamerick probably had the 3V version, which while more powerful was also more problematic with said phasers and such.

Welcome to the forum. We also upgraded to a 2019 Expy from our 2006 model. I would strongly recommend skipping the 2017 model and opt for a 2018 or newer. The 4th Gen Expys are a whole new beast. New frame, new suspension, new body panels, new dashboard, new electronics, etc. Look for a Gen 4, you'll be glad you did.

The 2017 is an excellent choice. I have 100K on my 16 and in 10 yrs it only needed one thing. The 17 has the more reliable 6sp transmission and better luck with cam phasers than the 18 and newer ecoboost.

My sister had a 2017 with the 3.5 turbo engine. After the cam phasers went out the second time, she traded it in...for a 2025 Tahoe. Now she is having problems with the Tahoe audio that the dealers can't seem to fix.

The 5.4 and 3.5 aren't comparable. The 3.5 out performs the 5.4 in every measurement. We've owned a 2003 Expy 5.4 since 2004. We've put 150k miles on it; it now has 182k miles. The only engine related thing I've replaced is the intake manifold because of the notorious crossover tube. The 5.4 is reliable.

We've also owned a 2016 Expy 3.5 since 2017. We've put 45k miles on it; it now has 80k miles. The only engine related work done is the water pump replaced by the dealer under the powertrain warranty. I've towed heavy with both and it's not comparable; fuel consumption isn't comparable; power performance isn't comparable. The 3.5 dominates the 5.4. The only thing I can't speak to is the longevity of the 3.5, but there are plenty of articles and owners claiming longevity with regular oil changes, so I expect to get there eventually.

Welcome to the Expedition Forum, SSCC !!~ I have found it to be so valuable and informative from very nice and knowledgeable folks on here. I am sure you will value it too.

We had a 2012 V8 Expy Limited EL that we bought new in 2012 and it ran perfect until the day we sold it, in 2025. That's when we bought our new 2024 Expy Limited MAX with the turbo V6. Even though the 5.4 V8 always ran fine and towed our Day Cruiser boat fine, it was NO power-house and this 2024 Eco-Boost V6 would run circles around our 2012 5.4, power wise. It also gets double the gas mileage of the 5.4 V8. The only noticeable difference that I immediately felt, was that the 2012 rode a little smoother that our 2024 does. Both had HD tow packages, and both had Pirelli Scorpion Tires on them, from the factory. When we bought our 2012 new, it had those Pirelli Scorpions on it and it wasn't very smooth either. As soon as it had 20K miles on it, I tossed the Scorpions and put on Michelins. BOY! What a huge improvement in ride and handling those Michelins made. Can't wait to put Michelins on our 2024 to see if it improves greatly in ride smoothness.

If you can swing it, I would agree with getting into a 2022 or later Expy with the upgraded V6 engine and very much improved suspension. If not these newer ones, I would at least try to get into a 2018 or later Expy. Be very careful buying, though, because a lot of these older Expys are just being sold by people who are getting rid of an expensive problem or problems. Anyway, that's my 2 cents worth, and wish you well, Lance

The 5.4 gets less MPG when normal driving.. but better MPG than the 3.5 towing. The 3.5 will accelerate crazy fast for a large car! the turbos are a huge help. I don't like the change from 19 mpg to 9 mpg while towing. The 5.4 went from 16 to about 13 towing the same trailer

I guess I'll pile on.

Bought a used 2002 Expedition with the 5.4 with about 30k miles on it. Solid engine. No issues that I can recall. Average MPG 13.267. Sold it at around 125k miles.

Then a 2011 F-150 with the Coyote 5.0. Another solid engine. Squirrels chewed through injector wires. Other than that, no problems. Average MPG 15.802. Traded it in on the next vehicle at around 45k miles.

Then a 2015 Expedition with 3.5 Ecoboost. Very smooth power. More pleasurable to drive than the F-150, though without that V-8 rumble. Only problems were failed spark plugs at around 70k miles. 100k miles in 8 years. Average MPG 17.290. Traded it in for a Dodge Durango R/T.

Traded the Durango in for a 2024 Expedition with 2nd gen 3.5 Ecoboost. Only 12k miles so far so still developing the relationship, but no problems. Average MPG 17.978.

In my experience and opinion, the 3.5 Ecoboost gives you horsepower and torque that are better than the 5.4 with MUCH better fuel economy.

Well, lets put it this way:

For it's time, the 5.4 was/is a BEAST, sans the phaser issues, which some have had, but others notta...

However, the 3.5EB was a new direction for the Expy, which mostly worked out pretty good, albeit with a few issues here & there too...the majority of which were resolved with the redesign as already mentioned...

But literally EVERY vehicle ever made has/had it's own little quirks from time to time, some minor, some major....

Personally, my 5.4 is over 16 years old, still going strong, and has only needed a few repairs, ALL of which were age-related (nothing lasts forever !), not because of bad design or low-quality parts or sloppy workmanship during assembly etc...

Having owned a 5.4 2v for a good time now, what I can say is that the v8 is amazing. Tons of low end torque, pretty reliable if taken good care of (over 300k miles on mine), and is pretty straightforward to work on. The fuel economy is decent on highway cruises for a v8 (around 15mpg) but it experiences significant drops once traffic starts. The most annoying things are vacuum leaks, which can be a nightmare to find. Also, the sparks should always be changed tightly on schedule and torqued perfectly, as these engines are too sensitive for such stuff (moreso for the later 3v).