Okay I know these are not the fastest trucks around but I'm trying to decide if I want to take my truck in for a checkup. Does the 5.4 not like to rev over 3k rpm? Because mine doesn't, it always shifts at or before 3k even if I floor it. I have no check engine light and truck runs smoothly as can be (still getting used to the vct noise on acceleration). My seat of the pants meter is just so underwhelmed when I punch it. I can rev the engine above 3k with ease with the truck in Park or neutral though. Could my cats be plugged without setting a code? I drove my buddies 08 Sierra 5.3 the other day and that thing screamed when you punched it, as in breaking rear wheels free and getting sideways, and it's bone stock z71 crew cab.

Short of taking it to an exhaustive shop, is there a good way to check operations of the cats? I should also mention I have 106k miles and original plugs along with the 3.73ls rear end, 4x4 super crew.

I run the torque app on my android phone connecting to a blue tooth obdII adapter to monitor the truck. The temps before and after the cat seem to be about the same.

Nice thing about the app is you can monitor transmission fluid temps in real time, great for towing. I have the tow package with big cooler and running temps around 150 degrees. I'm hoping to stay within 100 degrees above ambient temp, that's what my trailblazer would do with its aftermarket transmission cooler.

 

I have an edge evo I use to monitor things and I rev up to over 5000rpm when I hit it, I have always felt it revs up a little slower than other trucks but that seems to just be the 5.4

 

You need to take it in and have it checked out for sure
when was the last time you changed your fuel filter? Or the fule modual under the truck, when they go sometimes you don't get enough fuel.
And you should have had to change your plugs by now?
Hows your trans fluid? Has it been changed?
You may have several things all adding up
good luck

 

Transmission fluid is nice and red, smooth but firm shifts even at wot. I have not changed the fuel filter yet, just the air and oil filters. I have a fuel filter, just waiting for some warmer weather to crawl under and swap it out. Same with the fpdm, too cold to drop the spare and get a good look at it but from what I can tell looking through the wheel well, it looks to be mounted on spacers like the new design.

I'll try a wot run at lunch and see how long it takes to wind up, sure seems to take forever just to hit 3k rpm.

 

If you are only hitting 3k rpm at full throttle, something is up.....Mine hits that if I just step on it a bit(I baby mine admittedly and NEVER put it to the floor) and considering it is a 5500lb truck, moves along fairly well. The Fords never have the speed of the GM v8 but a lot of that is gearing and weight.

 

Mine floored the RPMs go up to like 5300 or so... Yes GM 5.3s are pretty fast!

 

There may be a slew of reason why your buddy's lights them up and your truck doesn't such as gearing, tire compound, and the road he lit them up in so I wouldn't gauge your trucks performance by that. My trucks shifts point are at or around 3k so I would say that's more a function of your tranny not your engine. These trucks are made for hauling not sprinting off the line so kind sounds to me like your truck is probably fine. For those with programmers that state they are easily seeing 5k my guess is that the tuner is just changing their shift points.

 

Yah my transmission is in a hot hurry to up shift at as low a rpm as possible, but that could be because I drive it like a granny to squeeze mileage out of it. I stomped on it on the way to lunch and it spun up to 3500rpm when I let off at 45mph. Just something to get used to but I will change out the fuel filter and inspect the fuel pump driver module. I plan on doing the plugs in the spring once I've run enough techron and sea foam through it to soften whatever carbon is built up.

After just one weak application of sea foam (I didn't have truck at full temp), it cleaned out the top of the engine I could see through the fill port in the valve cover good enough to eat off of. I'll sea foam it again on the next tank of fuel right before I change out whatever oil the gm dealer filled it with for motor craft 5w20, already put a motorcraft filter on too.

What temperature should I be seeing as normal non-towing for the transmission? I mostly drive in town...

 

The 5.4s werent the fastest engine but you should be getting over 3k if you floor it.

My experience driving a 5.4 expedition is that it usually shifted around 2500ish rpms.

 

normal shift points are 52-5400. up through the gears at WOT.