86Capri

I have a very odd problem. The truck has two symptoms that I can tell, First it has a slight stutter or hiccup when accelerating sometimes. Its mostly at mid highway speeds (45-60) when you go to accelerate. you ease on the throttle and it bucks or hiccups. This isnt a small miss or stumble, its like someone flipped a switch and turned off the power for a split second. The other symptom is that when you really want to go like up a hill, passing or heavy acceleration the truck acts like its fighting to gain rpm and has a bit of surging to it but it wont go. It runs great otherwise, idles good smooth as glass just driving around town normally, no codes at all and yes I checked for stored codes. I have a bluetooth reader that is paired with my stereo so i can see everything and run codes whenever I want. Now here is the weird part. If I floor it a few times it will eventually clear its throat so to speak and will run better for a while. The average fuel mileage starts to go up and it feels much more perky. It takes two or three times of just holding it to the floor and letting it get past all the surging and fighting. That does not totally eliminate the stutter but it helps it and it really helps the acceleration and fuel mileage.

Things I have done in the past year or so to fix it are, replaced spark plugs, removed and cleaned the throttle body, cleaned the K&N, replaced the Valve Timing actuators that are in the valve covers, replaced the TPS, unhooked the battery to reset everything, ran a few rounds of injector cleaner through the fuel side and ran seafoam in the oil. The truck is clean, has 185K miles on it, has been well taken care of and runs perfect otherwise. Not abused at all. Its a 2006 Lariat 4 door 4x4 with the 3V 5.4L with no mods other than the K&N filter. Gets regular oil changes and always quality fuels.

SCORGE

What about the ignition coils

tradosaurus

It sounds similar to my experience. When going up a slight hill it would feel like its jerking and stuttering a bit. What it was for me was that a few COP bolts were not fastened tight so that two COP were loose. The bolts were loose because the threads on the bolt looked galled. I replaced all the COP bolts and the stutter went away.

86Capri

All of the COP's are the original but feel like they are fine. I have had bad COP's before and this one feels ok. Usually I have had a rough idle or other misfire symptoms with bad COP's. The bolts are tight as well. I would hate to buy a whole set only to find out thats not it. Those are not in my budget right now but if the COP's are the cause I thats what I have to do. Just weird it does not pull missfire codes and it gets better after I floor it a few times. It has done this consistently since I have had it for the past two years.

tradosaurus

I've replaced all my COP's over a few months time ($30 / COP) so that I have a baseline of new parts. When I bought the truck (4.6L 2V) last year I didn't know what was replaced but after replacing the spark plugs I realize that I have a peace of mind with new parts.

86Capri

I am looking at COP's now. I can get off brand ones fairly cheap so may do that and keep the OEM ones as replacements. Mixed reviews on the cheap ones on amazon but its worth a shot.

PerryB

Replace the fuel filter. The symptoms you describe sound like fuel starvation to me.

redfishtd

The cel won't set until the threshold level is passed . Ford set it quite high . Mode 6 will tell you raw counts building per cyl towards setting cel . Its under test results on torque pro . New boots/ you can't see a pin hole for 30,000 volts ,cleaned cop terminals , all connectors locking on and cleaned . New plugs are sp546 ,recommend cleaning out cyl tip area of plug with carb cleaner ,carbon around tip breaks plugs going in and out . Sp 515 were done away with because of high failures out of the box . Torque plugs 25 -28 foot pounds with wrench not by feel . If you do it right it will go 60k but don't go past that .
Dielectric grease small amt on each end of boot , it is an insulator not conductive gel ,keep it mostly off metal parts . Its job is to stop heat seizing and water tracking .
Misfires show up under load in higher gears first ,low rpms with load ,hills etc .

86Capri

I actually bought one with the COP's. Not sure where its located on this truck but cant be too bad.

86Capri

Brand new plugs when I bought it, the ones in it were dead, learned the hard way to torque them with a torque wrench so that was done, I did check in torque pro a while back and showed no misfires at all. That is what was confusing me. I bought new COP's anyway. Will see how it goes after. Between that and the fuel filter I am hoping it drives like new.