Purchased a 2011 RDX with 134k miles a few weeks ago. It's in immaculate condition for it's age and miles. Came from Texas, so no issues with rust. It had over 40 service records dealerships.
Recently on a smooth, straight roads i noticed that the steering wheel resists automatically returning to center. If going straight and i slightly turn the wheel either direction, it will continue in that direction until i manually push it back straight. It seems to have the same resistance in either direction through the entire turns with no binding or certain spots or dead spots, no noticeable play in the steering. No leaks or bad hoses, no air bubbles in the reservoir, no loud whine from the PS pump. No alignment issues, if i put it straight, it'll go straight forever until you hit a bump.

Items i've checked:

• Removed tie rods on both sides and checked for inner/outer play and stiffness or cracked boots
• Removed tie rods and turned each tire by hand to check for resistance in ball joints, knuckles, and strut bearings. Not sure how accurate this is since suspension was unloaded.
• Brand new tires and alignment (issue was happening before tires/alignment, no change)
• Steering rack boots in great condition, no leaking, no squishiness to indicate internal leak
• "Power assist check" as per the service manual. This is tricky as it just states to read the scale "as the tires begin to turn". i measured 6-8lbs of force.
• Picked up a universal PS pump pressure testing kit but Honda/Acura uses a proprietary connector on the pump and hoses so that won't work
• Steering knuckles in the column seem fine. I'd have to remove it from the rack and pinion to confirm but i'd rather rule out easier items first

The PS fluid was changed/flushed around 74k so i will flush and change that next. If that doesn't work i'm considering adjusting the rack and pinions rack guide adjustment.

Anyone else run into this issue or have any other suggestions?

 

I have not had this problem, but I did Google it. According to a video, you car alignment just needs a little caster.

Since I don't really know what I am talking about, I will let you watch the video yourself

 

What if you jacked up the front end on put on jackstands then load one side at a time by removing the wheel and placing a floor jack under the lower control and raised the floor jack to put a good load on suspension and then manually move the opposite wheel to see if there's any binding, repeat for the other side. It sounds like the strut upper mount/bearing or ball joint (less likely) may be binding but needs to be under load to find out.