EPAS Terrible Shudder

Discussion in '2011+ Mustang GT 5.0L Tech' started by jsnyng, Jul 6, 2011.

  1. jsnyng

    jsnyng Senior Member

    982
    4
    I'm posting this for a friend/fellow autocrosser, Terry Fair, the owner of Vorshlag. Have any of you guys seen or heard about terrible EPAS shudder in the steering wheel? Know how to fix it?

    Click the pic for the video...

    [​IMG]

    From this article --> http://www.themustangnews.com/content/2010/02/tech-2011-mustang-electric-power-steering/

    One of the new technological features of the 2011 Mustang has gotten a bit over-shadowed by all the whooping and hollering about the return of the 400hp 5.0 V8, the 305hp standard V6 and now the all aluminum 5.4 liter 550hp GT-500 engine.

    What lies beneath those great new power plants is a new elecronic power assisted steering (EPAS)* rack that amplifies the new power and efficiency of those engines. Additionally, this change represents a first use of this new technology in a muscle car, let alone the Mustang.

    The main benefits and reasoning behind moving to electric assist is the elimination of the weight, drag, and complexity of the engine driven hydraulic pump. Not only has horsepower been freed up, more efficiency gained,* the power steering as a system been reduced to a single self contained component. The system saves approximately 3 hp and increases gas mileage by about 4% claims the manufacturer of the unit, Nexteer.

    The best part of the new system for driving enthusiasts is the inherent handling precision improvements it brings. Hydraulic power steering systems by design place a cushion of hydraulic fluid between the actual steering gear and steering shaft. When you turn left or right you are getting a little bit of slop, a bit of lag as that hydraulic fluid is moving in and out of an actuator valve that controls steering boost. Though minute in the grand scheme of things, this removes a lot of steering feel and that direct gear to gear connection that allows a driver to pick up on messages the tires are sending up the line.

    In the case of Mustang’s electric power steering assist system, the steering shaft is solidly connected to the pinion gear that acts left and right on the rack. A non-touching sensor resides at the base of the steering shaft that picks up the driver’s inputs and passes that information along to the electronic control unit. Power assist is given through a separate pinion gear located on the opposite side. So there is nothing coming between you and the feel of the road.

    Because the system is controlled electronically, software can monitor various other conditions such as vehicle speed, steering angle, and traction conditions to give variable levels of assist. This means that Ford has been able to program the system to give more assist at a stop or at slow speed such as in a parking lot. Conversely, less assist is given at high speeds to give you a heavier steering feel for more control. In the presentation of the new 2011 Shelby GT-500, the SVT engineers stated that they spent a lot of engineering time programming the system to allow maximum road feel and handling characteristics.

    Ford says that EPAS has made a dramatic contribution to the 2011 Mustang’s driving dynamics, delivering quicker on-center steering response, increased effort at highway speeds and reduced effort required in low-speed parking maneuvers. EPAS will have* specific tuning for each Mustang model.*
     
    Last edited by a moderator: Jul 7, 2011
  2. Ruger51

    Ruger51 Junior Member

    10
    0
    Mine does it on high speed sweeps at 80. I am interested in the outcome.
     
  3. hawkeye18

    hawkeye18 omgwtfbbq

    234
    2
    Look on the bright side; she's getting a heckuva hand massage, amirite?

    That is a bit weird, and kinda sounds like the shaft position sensor isn't working quite right.

    I've noticed sometimes that my car will "brake steer" - just like torque steer, only during braking. It's like one of the rotors isn't working right, but it's very rarely repeatable. It's a once-in-a-while condition, which leads me to suspect it's in the steering. The reason I think that is that it doesn't feel like the wheel's being pulled... it feels like the wheel's doing the pulling. Kind of like a force-feedback wheel on a PS3, only in real life.

    Fortunately, I usually drive with two hands, so it's not been a big deal so far.
     
  4. 2000mcr

    2000mcr Junior Member

    11
    0
    Google Ford TSB 10-16-4

    Its for the GT500, but might end up being a GT issue also.

    Paul.
     
  5. VTXFrank

    VTXFrank Obama SUCKS!

    8,217
    67
    Man, I've driven the piss out of my car and have never had that happen. However, I'm glad to see this video so if it does, I'll know something about it.
     
  6. jsnyng

    jsnyng Senior Member

    982
    4
    Thanks for the info guys. Hopefully that TSB will help Terry get some movement from Ford.
     
  7. JDos1

    JDos1 forum member

    186
    0
    Mine does it at higher speeds. 80-100mph range and is only minor, as if there's a wheel out of balance.
     
  8. Bmr4life

    Bmr4life 2005 GT

    1,147
    0
    Never seen it, but only have a couple hundred miles.
     
  9. 94tbird

    94tbird 4R70W FTMFW S197 Team Member

    Age:
    37
    12,732
    55
    No need to make references to Nazi's, OP. Rules are rules, follow them or there are alternative sites to visit. I removed the sentence.

    Now on to your issue, that is pretty messed up. Thats why they have warranties. Take it to the dealer. Sounds like the EPAS needs a new configuration program. Thats the first thing I would have done over changing 3 sets of tires, springs, ect.
     
  10. Vorshlag-Fair

    Vorshlag-Fair Official Site Vendor Official Vendor

    1,393
    51
    Thanks for posting this here - should have looked at this forum first. :)

    Well the car is a bit modified so its going to take some work to get it to the dealer without being banned for life. :D It was also a gradual thing that has worsened recently...

    [​IMG] [​IMG]

    We use 3 different sets of wheels & tires for street, track and autocross uses, so that variable was more of a "what was on the car that day" type of testing, as were the springs. We talked to one tuner that thought it might be excessive camber (-3.5°) so we spent a few minutes pulling the camber out for retesting the EPAS problem, plus the various traction control modes. Nothing we changed affected the result. Shot the video and figured somebody would recognize this issue... which is what happened, and we had 5 different sources quote the same TSB. Once again the online community knew more about this car than the Ford mechanics we spoke to or the Ford shop manual (which has zero diagnostics for the EPAS).

    [​IMG] [​IMG]

    The Mustang currently has several warning lights due to things we've removed, so we'll swap in the stock seats, pull the CAI and tune off the car, slap on the stock wheels/tires, and take it in to Ford for the TSB reflash.

    Thanks again,
     
  11. 94tbird

    94tbird 4R70W FTMFW S197 Team Member

    Age:
    37
    12,732
    55
    is it possible the sensor is gonig bad? have you tried to remove/replace it? Is it even a servicable part?

    "A non-touching sensor resides at the base of the steering shaft that picks up the driver’s inputs and passes that information along to the electronic control unit"
     
  12. KJGT

    KJGT forum member

    317
    1
    That is of course if Ford will do anything about it after changing the suspension.

    I have never had any issues and I have been around quite a few sweeping corners at 80+mph with a couple different sets of wheels/tires. Some claim that the Brembo cars have a different steering calibration, wonder if the guys having problems are Brembo cars.
     
  13. 94tbird

    94tbird 4R70W FTMFW S197 Team Member

    Age:
    37
    12,732
    55
    seems they have a different unit for each wheel combination thecar can have. Maybe thats your problem. jsut throwing it out there


    Description Year MSRP Price Core Price Your Price
    Steering gear, mustang, 17" wheels, to 5/13/10 - power - electric - POWER - ELECTRIC
    2011 $761.72 $400.00 $628.42

    Steering gear, mustang, 17" wheels, from 5/13/10 to 8/16/10 - power - electric - POWER - ELECTRIC
    2011 $1,104.57 $400.00 $911.27

    Steering gear, mustang, 17" wheels, from 8/16/10 - power - electric - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 18" wheels, from 8/16/10 - power - e - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 18" wheels, from 8/16/10 - power - e - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 18" wheels, from 8/16/10 - power - electric - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front and rear wheels, from 8/16/10 - power - electric - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front and rear wheels, from 8/16/10 - power - electric - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16 - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16/10 - power - electric - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30

    Steering gear, mustang, 19" front/20" rear wheels, from 8/16/10 - power - electric - POWER - ELECTRIC
    2011 $1,070.67 $400.00 $883.30
     
  14. Digital_Synapse

    Digital_Synapse forum member

    1,795
    1

    Oh, my, God. So I have to change this thing out for a different set of wheels?!? WTF!?
     
  15. 94tbird

    94tbird 4R70W FTMFW S197 Team Member

    Age:
    37
    12,732
    55
    dont know, jsut showing all of those combinations when i check out tousley ford parts
     
  16. 302

    302 Senior Member

    5,401
    14
    Has anyone had any shimmy problems after installing aftermarket wheels? I really have not read about any problems.
     
  17. VTXFrank

    VTXFrank Obama SUCKS!

    8,217
    67
    I haven't. But I also stayed with 19" wheels and tires all around. That could be a factor in why I've not had this issue.
     
  18. Bmr4life

    Bmr4life 2005 GT

    1,147
    0
    My 20s are smaller than the 19s that came with the car and I've had no issues yet.
     
  19. 302

    302 Senior Member

    5,401
    14
    Hmm so if i have 18's going to 20's i may have an issue. I have my old 20's off of my black car sitting in the garage, i may do a little experiment.
     
  20. sean858

    sean858 forum member

    95
    0
    I recall reading that the Ford EPAS can make adjustments for out of balance wheels. This makes me think it may be a malfunction of that system/ECM logic. Dumb question I'm sure but with the significantly smaller tires your running is the revs per mile properly set? I would assume that system would have to use wheel speed one way or another.