I have an '05 F150 XLT 5.4 Triton RWD. I purchased it used a few weeks ago. Today was the first day I drove it on the interstate and I noticed some random intermittent sputtering. It would mainly happen when during light acceleration above 60 mph. (Such as accelerating with the cruise control, or lightly applying the accelerator) it seemed to stop or be drowned out under harder acceleration. There was no noise when this happened, just a feeling of the truck jerking slightly. If anything there was maybe an absence of a noise from the exhaust but it's so brief I couldn't tell for sure. This would normally happen when going up hill and adding that little extra gas to maintain speed. It would happen straight or in a turn.

I'm thinking either bad gas (I did fill up before leaving, but I have no Check engine light and the truck runs like always otherwise), a wheel issue, or maybe it's time for a tune up?

Does anyone have any input here or has anyone felt with this before?

UPDATE: Drove home from Chattanooga today and I narrowed down the circumstances where this occurs. It only happens only when all of the following conditions are met:

• Driving up hill (even slightly)
• Driving over 50mph (the higher the speed the more likely it will happen)
• Light pressure on the accelerator
• RPM ~1500 to ~1800

If any of these conditions aren't met, it stops happening (Or I can't notice it). For example if I'm driving down hill it won't happen, or if I accelerate enough that the RMP jumps to just over about 2000 it stops. Keeping this in mind I was able to drive home with no trouble. I did try driving on the Interstate for a second but the higher speeds make it more likely to happen.

I'm working on my suspension tomorrow so I'll try and find time to do a tune up as well and post my results.

 

Josh (@jwhitman922) where in the world did you find an "F159"???? Lol - JK.
Welcome to the forum and nice looking truck. And we all want you to have it and enjoy it for a long time too.


Reviewing your profile (skimpy) and prior posts, you did not mention miles or last good tune up. But - without a doubt you are experiencing is a misfire under light load. Confused and mis-diagnosed by the best of mechanics and forum members here ranging from Transmission Torque Converter to replacing the engine. So take a deep breath.


The design of the 5.4L pushes the limits on several fronts for fuel efficiency and emissions. Everything needs to be near perfect to avoid misfires. Your truck is geared to operate at verl low rpm, deliver good torque on low octane fuel, and deliver pretty good gas mileage.
I would recommend: Do not let the situation continue, and do frequent changes with good quality 5W20 synthetic Motor Oil and frequent changes - using only Motorcraft oil filter, or you will face the second most common problem for the 5.4l's - broken cam chain guides and Phaser replacement / timing job.


Your stuttering can be cured by doing a GOOD / CAREFUL / CLEAN / THOUROUGH spark plug change with Motorcraft plugs - taking care to avoid greasy finger prints on plug ceramic. Clean ALL carbon out of the extended depth spark plug holes in the cylinder head. Replace ALL boots and springs. Clean electrical connections on top and bottom of COPs. Clean all debris out of spark plug wells. Replace Boots and COP Springs, and use dielectric grease, replace ANY broken COP plastic snap connectors. And torque new plugs to spec (25 ft-lbs). NO quick / sloppy workmanship.


If you do this. I can guarantee you - your skip will disappear.


Good Luck.

 

Hey thanks and yea F150, sorry Fat fingers. I'm about two hours from home, so I'll have to do that when I get back. I'll probably take the back roads to keep it away from interstate speeds, since its only happened above 60 Thanks for the advice!

And Mileage is 83K. As far as last tune up, the dealer didn't have that info.

 

I don't know if you got your problem fixed, but similar thing happened with me going up hill and it ended up being the spark plug boots had some cracks and needed to be replaced.

 

I read the mode $06 on it myself and found several misfires on the #2 cylinder. I took it back to the dealership and they replaced the coil for me and it runs great.

I went ahead and picked up new coils and new SP-515 plugs but I'm not to psyched about changing them, given the issues with the factory plugs.

for the yall!