I bought a 2017 super crew xlt with the 5.0 used with 13,150 miles on it around August 14th. I love the truck, as it is today I have like 14,620 miles on it and I heard and engine rattle that does not sound good. I was slowing down, then without coming to a full stop started to accelerate and the truck stayed in 3rd gear and the rpm's were right above 1000. I heard it and was like I hope that's not my truck so I kept trying to replicate it and truck did it a bunch of times today. Anyone out there experience this, heard of anyone with this issue.

 

Low rpm, high load, sounds like simple detonation. Did you use some bad gas? First thing I'd try is a tank of 93.

Addendum: Also try running in Sport mode, it'll keep the revs higher.

 

Ok thanks for the reply. I don't think I got bad gas but yeah I'll try higher octane and I've driven in both tow haul and sport before just don't want to 100 percent of the time but maybe I need to. Thanks again

 

this. 1000rpm in 3rd gear is really lugging the engine....an engine that doesn't make a ton of torque down low (especially that low).

 

Are you sure the noise wasn't coming from the drivetrain? These trucks can be quite noisy when switching from decelerating to accelerating at low speeds, due to slop in the driveshaft, etc. I know mine makes quite a bit of noise sometimes.

 

Not to hijack your thread but:

I have a similar issue with my 3.5 NA. Under hard acceleration (3-5000K rpm) I hear a fast loud ticking or clacking when my windows are down reverberating off of the curb. At first I thought it a rock stuck in my tire tread but it's much louder than that. Sounds kind of like something caught in the spokes of a bike wheel but it's not always there when driving and only shows up under hard acceleration and usually only within the first few minutes of driving.

It doesn't really sound like it camshaft related but it could be. Perhaps an exhaust leak that only shows up under higher back pressures or a vacuum leak. Even thought it was a cracked exhaust manifold but I didn't see anything on the top side when I looked. Any advice on what to check before I bring it to the dealer only for them to say they can't replicate it?

 

Sometimes I wonder if in desperation gas stations put 85 in their 87 tanks.

 

That absolutely happens where I live.

Usually the tankers come out of Vegas and their reg unleaded is 87. When the tanker comes from SLC their reg unleaded is 85. Obviously the stations are supposed to mark the pump accordingly (some do, some don't) but as they don't usually reload from SLC they figure it doesn't matter. They don't expect anyone to notice.

 

I don't think I'd want to run 85 in a 10.5:1 port injected engine. 87, to me, is pushing it. Even Ford suggests running higher octane for better performance and always when towing.

 

I've become accustomed to driving my truck in sport mode even though I am not an aggressive driver.
I just like how it drives better, and it virtually eliminates lugging the engine like you experienced. Under load of any kind 3rd gear and 1000 rpm is hard on the 5.0 engine.
These engines like to rev, and the sport mode just helps aid in that. If there is a fuel mileage difference in sport mode, it must be very small, as i occasionally use regular mode and do not notice the difference. And if there is a difference it wouldn't bother me to lose maybe 0.4 mpg or whatever it is.