freebird518

Hello F150 forum,

Yesterday began this mystery of an odd noise when under engine load.
It sounds pretty high pitched, and when i let off the throttle it seems to go away, or if i increase the acceleration it seems to go away.

I know it is not the following:
- Not 4x4 IWE's
- Not Intake rattle

Possibilities:
- Heat shield rattle
- VCT issue
- Cats?
- ?

The Idle noise has not changed, and i am not hearing the "Infamous VCT Diesel" noise at idle.

Any insight would be helpful, I am changing oil tonight to see if the filter is clogged or anything of the like.

Thanks
-Nate

Especial86

iTrader: (1)

If its a "whine" that sounds like its coming from the driver side when in the cab then its your alternator.

freebird518

Ive had that sound before, But that happened at idle as well. This is more of a Rat-ta-ta-ta-ta-ta, Im leaning more toward Catalytic converter. Truck has 177k on the original cats, and i went through the whole plug/misfire issue 2 years ago.

crossbones

Is your ac running when it makes the sound? Mine makes a sound with ac on. It is the drivers side cat.

freebird518

Ive had that sound before, But that happened at idle as well. This is more of a Rat-ta-ta-ta-ta-ta, Im leaning more toward Catalytic converter. Truck has 177k on the original cats, and i went through the whole plug/misfire issue 2 years ago.

ALSO this does not sound like a warped manifold, been there, done that haha

freebird518

my truck loses a lot of power when running AC now, I do not remember it being that way last summer, also never had this sound. Hmmm

crossbones

I have been getting a code for bad cat on drivers side for a while. Saving up money for new magnaflow high flows. Anyway, lately I have been getting a rattle under driver side, but only when ac is on. I can turn off ac and rattle will go away. No other codes being thrown and ac works great. I did just replace both manifolds with the dorman brand manifolds which really quitened down my exhaust leak. Cats go on next week.

freebird518

what year is your truck? 5.4 i assume?

do you have a good guide for the magnaflow cats or do you know if wide band O2 sensors need to be run?

crossbones

From reading on this and other sites, I chose to go with the 94106 high flow cats from magnaflow. As far as the O2 sensors, the advice is to just use old sensors as long as they are good and the back O2 sensor should be bunged in about and inch or so back after cat. My truck is an 05 with 5.4.

freebird518

new belt = Sound gone. I guess i was over thinking it....