Just took a 16 hr drive to Orlando, FL and noticed this again.
When holding a constant 70+ w/o cruise control..there is an occasional hesitation (only way I can describe it). It almost feels like a 'bump'. It's quick, but I can feel it. It almost feels as if the trans was ready to downshift, but didn't. I have not seen any indication of rpm change, but it happens so fast, I doubt I would see it even if I could watch the tach the whole time and the tach is dampened so much, I doubt it would show if there was a change.
4.6, 3v 2wd, Screw.
Has anyone else felt this?

 

I feel this on every road trip. I haven't figured it out either. It feels like a coil pack miss.

 

That would be my guess - a random misfire, however caused ( Cop, harness, injector, plug, etc)

Not sure whast the threshold is for the PCM storing pending codes for this behaviour, but I would suspect the only real way to find it is to instrument the truck - or a shop test that simulates the conditions under which it occurs.

This is classic fodder fer a "No Problem Found" response from a Dealer warranty claim.

Good luck.

 

Thanks guys. I'm taking her in for an oil change / tire rotation soon (they had a deal..$64 for 4 oil changes..couldn't pass it up!). Will have them check and will report back if I get any solution from them. It's not detrimental to performance..but annoying.

 

I have the same thing that happens. I had a 2002 Screw with the 2v 4.6 and it did the same thing. It feels almost like the fan for the air conditioner is kicking off.

 

broken coil spring, idk but it happened to me and that was the problem

 

Same thing happens to me. 2009 4.6L 3V SCREW. Dealer told me it was unbalanced tires, they rebalanced them and the same problems still there. Let me know if you figure it out.

 

How could a hesitation be anything but engine or maybe tranny related?

 

UPDATE:
OK guys..I'm embarrassed that I didn't figure this out earlier..
Just took another long trip and on the way back I needed the defrosters occasionally. every time I turned on the defrost (from vent)..which ACTIVATES THE AC!!!..I felt it. As long as the defrosters (AC) were on, I felt the 'hesitation'. I'd turn off the defrost, it was gone for miles (and hours)..
So..I guess that slight hiccup is the ac clutch kicking in. Surprised that it can be felt, but it sure seems to be the culprit.
So for those with a similar issue..try turning off the hvac system and see if it continues. Still is slightly annoying, but I feel better.

 

Same thing with me 2010 4.6 3v scab 4x4 3.73. At speed on the highway it feels like a miss or the trans about to shift. I will try to shut off all HVAC stuff and see if that does it.

 

I've experienced this on my last three trucks (all 5.4's) and it's the A/C clutch kicking in.
After a while, you will likely get accustomed to it and it won't bother you.

 

Its happened recently and I am only using heat now. Could still be something kicking on. The hesitation almost feels random though.

 

^^ Remember... the A/C clutch kicks in on defrost too.