So, my steering is perfectly fine until I make a tight U-turn. After the U-turn, the steering will pull in the opposite direction of the U-turn. This behavior continues for some time and seems to always "reset" after the car has been turned off. The power steering fluid is between the marks on the dipstick. There do not appear to be any obvious obstructions of the column or steering shaft. There is a partially torn bellows on the driver's side, but it is not immediately obvious how that would cause this. Anyone ever have this type of behavior or have some ideas on what to check?

EDIT: Forgot a key detail, but I think it was implied. Before a U-turn, the alignment feels perfectly normal and the car tracks straight with no effort to keep the car on course.

 

steering rack bushings? if these are bad/loose the rack can actually move side to side

 

So to clarify, if you shut the car off and turn it back on again, it goes away immediately? I know the S5 system is a bit different from S4, but the power steer computer senses steering angle as well as speed. The fact that your symptoms go away when power is cycled (and only appear after a tight turn) suggest electronics to me.

Do you have a spare PS computer you can swap out?

 

I'm not sure I understand what the problem is based on description. Are you saying that after doing a tight U-turn, which kind of implies turning the wheel one way or the other to full lock, when you straighten out and drive off that the car's steering feels like it wants to pull one way or the other? If so, that might indicate an issue with your alignment, steering linkages or rack perhaps. Or are you saying that after a U-turn or full lock turn, the PS system feels like it's giving you too much assist and making the car's steering pull in one way or another & feel unstable? If that's the case, and you have the vehicle speed sensitive PS system (IIRC, that PS type came with all S5 T2's), it could be an issue with the PS controls/sensor or the electrical valve on the PS pump.

 

The bushings appear to have some age cracking on the exposed portions, but I can reach down and tug on the rack and not see/feel any movement. If I take the rack out for any reason, I am going to replace them though.

Hmmm, now I think I will need to try this. Take it for a test drive, do a u-turn, observe the behavior, pull over, shut the car off, and see how it is once restarted.

 

The first. And I've already kind of messed up by misremembering the problem. I just took it out, did a U-turn, so nearly full lock to the left, and after straightening the wheel, it pulls to the left. I misremembered which way it was pulling after the U-turn. Then, as I turned off of the road to the right into a parking lot, the car stopped pulling and tracked straight again. Alignment would certainly be a possibility, but the nature of the problem (only pulling after taking the rack to lock/near lock) makes it feel more rack/electronic related. This car does have the vehicle speed sensing steering.

 

Try unplugging the computer and see if it changes anything?

 

Finally had a chance to try this. I unplugged the seven position connector at the PS computer under the dash and it changed nothing. Still pulls the same way after taking it to lock or almost all the way. I guess I may be looking at a rack rebuild or purchasing a remanufactured one. This is quite the annoying issue, so I'll be looking to do this soon.

 

if the bushings are bad the rack can physically move side to side, which would be your symptom

 

I'll have to find a helper (my 12 year old should work) who can move the wheel lock to lock in the garage while I observe.

 

If need be, disconnect the tie rod ends and move each wheel assembly to be certain nothing is binding.

 

What about disconnecting the harness at the pump? I'd imagine the power steering should still work, and that would guarantee it's some kind of hydraulic/mechanical issue (between the pump and rack) if it continues doing the exact same thing.