rickyp

My 08 4.6 4x4 XLT with about 25k on it most over the road miles.

I have been noticing more and more a vibration when I am at a stop light. I can really feel it and so can my wife on the passengers, some times it is more noticeable then other times.

The truck is not trowing any codes and it is mostly stock, but I do have a K&N replacement air filter in it.

Is this normal or is there something going on? I am taking the truck in for oil change and trire rotation on Tuesday and I don't want the dealer to tell me this is normal and push me out the door.

Mod (Ret.)

What kind of gas are you running? Lots of folks are running the cheap "jiffy mart" gas these days to save a few pennys per gallon. Could be that the injectors are dirty. Try some injector cleaner in the next few tankfuls, and/or switch to Mobil or Shell, as they use cleaner/aditives in thier gas to keep the injectors clean. 3M makes an injector cleaning kit that a "do it yourselfer" can do in the driveway to clean the injectors as well.

rickyp

actually I run shell 86 about 98% of the time and the other 2% is Exxon and a few times BP.
I this truck has never seen a discount gas station.

I doubt it is the injectors (well it could be) I have the dealer do "the works" oil change package3 times already and they are suppose to put in fuel cleaner in it.

Mod (Ret.)

Well the good gas rules out dirty injectors then. Seeing as how you only have 25K on the engine, the plugs can't need changing, and the plug wires must be great too. I'll assume you have the 5.4.....some are saying that when a CAI is installed without a custome tune, it can lean the stock factory's tune, so perhaps this is what you're experiencing.

I have a 4.2 V6, and have several mods to it (CAI, exhaust, superchips performance tune). I have two sets of plugs; I remove one set eact year and install the other to inspect the engines "performance", as the plug color can tell you how the cylinders are burning. On your late model 5.4, you should not have the plug breaking problem, so you might want to remove a plug or two to see if it's burning lean.

Does the engine ping when you hit the throttle?

rickyp

I have the 4.6 (listed in the first line) and no cold air intake just the reusable K&N air filter

GATORB8

Since you're under warranty, take it to the dealer and talk to them about it.

To make sure you're not just pushed out the door, ask to sit in a new truck at idle and see if the vibration is there. If it's not, they should figure out why it is in yours.

It could be a few things, from a dirty throttle body to a burnt valve. A lot of things can cause a rough idle like that.

FYI, K&N will back you up if they try to blame something on the filter.

rickyp

I have a few friends that have a 150 and one of the fire stations I work at has the same truck as i do. I am going to that station this evening so I will take it out for a little test drive and see. I dont remember the truck doing it when new, I can only remember it doing it for the past few months.

I dont see how it could be the air filter since it is a replacement and not modified anything.

GATORB8

I've heard of some people blaming dirty intake components on the fact that the K&N filter is oiled.

rickyp

I have yet oiled the filter. it has only been on my truck for about 6 months. I am going to get the cleaning kit soon and clean it for the summer.

GATORB8

They come pre-oiled.

I'm not saying the oil did anything, just giving you a heads up of a possible warranty excuse the dealer could try to pull.