Low whistle between 1500-2k RPM on light load?

[BigRedSHO]

Hey all! Still waiting for a wash to upload SHO pics (Washington rain), but I have been having a low whistle that will change pitch through 2k rpm until it pretty much fades completely, and I am wondering if anyone has run into this and what it can be attributed to. At both cold or normal temp running, under light load, the pitch starts low at 13-1500 rpm and will increase pitch, not necessarily decibel, through to around 2k plus or minus 100 rpm, and under heavy load, it doesn't exist in that range. Im finding it just a bit weird, but the car is running solid. Just curious, and thanks all for the assist on this! -Red

[SHOdded]

Unfortunately, that could be just about anything.  The first things to check would be all hoses (looseness, cracking) and clamps.  Hopefully it is just a vacuum leak of some sort.  There ARE smoke-in-a-can products to help with that if need be.  Other things (not so frequent in occurrence) include bearings, belts, and trans/PTU gears.  So if you can use a mechanic's stethescope to narrow down the location, that would be immensely helpful.

[BigRedSHO]

Thanks, SHOdded! Yeah I am going to check around the clamps and fittings today, and will post the finding. Do you think that the exhaust manifolds could play a part if the gasket is cracked or has broken a bit loose? Only reason I ask is every once in a while, it seems I get a rattle, but I can never duplicate on command, and my local dealer gave me deer in the headlights looks to what I described. Just curious. -Red

[SHOdded]

More likely the gaskets on the downpipe to catback interface than the ex manifold.  Intake manifold gasket could be a culprit though.

[ZSHO]

Bigrs is the car still currently stock,no aftermarket intake?? Z

[BigRedSHO]

As far as I know, it is all still stock. I have some lifts nearby I will try to get some time on, but not until the weekend.

[ZSHO]

I certainly agree with SHOdded in regards to the gaskets on the DP,with the exhaust heat level reaching around 500 deg probably have an air leak on one of the banks,had mine changed at the dealer while changing the PTU fluid and my rough idle is cured,pic's below.  Z       http://www.tascaparts.com/auto-parts/2010/ford/taurus/sho-trim/3-5l-v6-gas-engine/exhaust-system-cat/exhaust-components-scat       http://www.tascaparts.com/ford/taurus/7t4z9450aa/2010-year/sho-trim/3-5l-v6-gas-engine/exhaust-system-cat/exhaust-components-scat/?part_name=flex-tube-gasket&position=right    http://www.tascaparts.com/ford/taurus/7t4z9450aa/2010-year/sho-trim/3-5l-v6-gas-engine/exhaust-system-cat/exhaust-components-scat/?part_name=muffler-and-pipe-gasket&position=left

[ZSHO]

I would also try grabbing a rubber mallet while under the car and gently hit the exhaust and DP one small section at a time to possibly track the rattle,not quite sure if the two are related but sometimes due to temp fluctuations my exhaust rattles upon morning cold startup,best of luck and keep us updated.  Z

[BigRedSHO]

Z, will do! Thanks all, I will make sure to get some closure posted on this ASAP.