Middle of May, I went to Boston. On the way there, I started to notice a slight whirring noise that was only present when I gently feathered the gas to maintain highway speed. If I were to apply any more throttle, the noise would go away, and if I were to pull my foot away and allow engine braking, it would also disappear. So I did my best to finish the trip to and from Boston adjusting my driving to avoid the noise. Once I came home, I researched and thought the noise might have been my wheel bearings (I had just replaced lower control arms, lower ball joints, inner and outer tie rods prior to leaving for Boston). I also had a shop install my upper strut mount bearings and bushings simultaneously with the wheel bearings.
Since then, the problem still continues. It has grown louder, but still occurs under the same situations. I've focused more on it and here are the conditions under which it occurs:
1. Car must be warmed up. Starting it up cold and allowing SAI to run then driving, car is fine, no sounds. Usually takes 20-25 mins of driving to get it to start making noise.
2. Car still only makes the noise when the gas is being feathered (ie barely pressing it enough to give it any sort of throttle. It does also make the noise between shifts when reengaging the gear and applying gas, as the throttle pedal passes the point of throttle off to throttle on.
3. I'm hearing more noise now during engine braking than I had been previously. Could be related?
I posted in the Manual Transmission section, but got very few replies. I'm really at a loss for what this could be. I took the car to RSWorx near me and the technician rode along for a few minutes and told me it sounded like something rubbing the driveshaft but that didn't seem to make sense, especially when he didn't have an answer as to why it would require warming up to do so.
I'm starting to feel more and more like it may be the input shaft bearing. The noise is more present now between shifts as I change the throttle. Also, I'm hearing it more now even under engine braking entirely (no throttle used).
In 6th gear, I'm feeling a pulsing in my accelerator at around 3000rpms (80mph)