wbax123

Bought 2009 F150 Lariat, 5.4 with 82,000 miles. New sound developed and it varies based on RPM; at approximately 1200 RPM under very light acceleration I get a quick growl (lasts no more than 2 seconds) that seems to come from the drivers side under the hood. It sounds like it comes right up the steering column at times. The sound level changes, sometimes you have to really list for it other times it's blatant. The sound varies by RPM; and drops off if you accelerate even just a little bit more. There is a clear RPM range: 1200 to 1400, it doesn't occur outside of that.

Dealer did a reflash on the PCM one week ago, sound developed after that and it's routine unless I accellerate through it.

Thoughts?

Also have the sporadic misfires for them to find, most noticable at highway speeds; lifter noise also on drivers side. Dealer service manager says to run heavier weight oil and lifters will be quiet. ?? Need Ford Dealer to put that in writing before I change oil weights.

Any help is appreciated!

texasedition

It may still be in a relearn process right now. It can take a while sometimes for the computer to learn a new strategy.

wbax123

Thanks Tex, I will listen this next week or so and look for improvement. I don't know when or if the fuel filter was ever changed, so that is where I want to start on the misfire issue. I will likely 'demand' the dealer change the 'noisy' lifters, changing oil weight is a temporary fix. Going out today to try to find the vibration/pulley noise. I'll keep you all posted on wht I find there.

Thanks again!

texasedition

Never hurts to change a filter