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Heavy Steering on Cold Mornings

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by A4_MaJiK, Aug 31, 2012.

  1. A4_MaJiK

    A4_MaJiK Azeem

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    Yesterday morning and this morning when leaving home for work the steering felt heavy. I tried recycling the ignition to try to restart the system but this did not work. I then waited for the engine to warm up (once I had reached a set of traffic lights in Coventry) and then attempted a restart of the engine and success! The system was fully functioning once again.


    I haven't checked the PAS fluid level as of yet as I thought of it as a one off yesterday morning and I have not yet had the chance either. I will pursue the issue on my own accord to determine the fault as my suspicion is that it may simply be low PAS fluid level in the system which simply just expands once the engine has warmed up.

    I'll let you know how I get on anyway but just wondered whether anybody else has a had a similar sort of experience or issue before?

    Thanks, Azeem.
     
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  3. jdp1962

    jdp1962 Grumpy Old Moderator
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    IIRC, these models have the speed-sensitive power steering. It could be that something in the speed-sensitivity circuitry - a fuse maybe - has packed up, leaving you with the default level of power assistance at all times.
     
  4. A4_MaJiK

    A4_MaJiK Azeem

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    You're right about the speed sensitive steering (Servotronic) but I don't believe that is the problem in this case as it comes back once the engine is warm and if I go out to drive right now there's no problem there. Only first thing in the mornings. This leads me to believe that the problem is related to PAS fluid level.

    I'll check the PAS fluid level out and let you know how I get on. Just to confirm, when check PAS fluid level does the cap need to be screwed all the way down or do you just keep it above the threads?

    Azeem.
     
  5. NHN

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    Good question, imho should be screwed all way down, but check the manual to be sure.
     
  6. A4_MaJiK

    A4_MaJiK Azeem

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    Checked the PAS fluid level over the weekend and it was well above the MAX mark so took some out and left it slightly over the MAX marker as I thought it would have expanded (checked level when fluid was hot).

    Had the same issue again this morning although I didn't have to wait so long for it to return to normal so thinking I still need to correct the level a bit more.
     
  7. A4_MaJiK

    A4_MaJiK Azeem

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    Went to correct the level yesterday (engine hot) and the level was within the margins. Had same issue again this morning although didn't last so long (did require a restart cycle for Servotronic to activate). Surely this isn't normal?
     
  8. A4_MaJiK

    A4_MaJiK Azeem

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    Just a quick update: decided to bleed any air out the system last night after I got home by removing the PAS fluid reservoir cap and going from lock to lock a few times.

    Seemed perfectly fine this morning, Servotronic was active immediately and PAS was behaving as normal but will let you know on any further future occurrences.

    Azeem.
     
  9. NHN

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    Thats great mate & also good you've been updating the thread with your findings/fix.
     
  10. A4_MaJiK

    A4_MaJiK Azeem

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    Unfortunately the problem has reoccurred again this morning, it was only 13'C outside so not exactly extreme temperatures. I'm baffled as to why it only happens in the mornings as it almost seems like an electrical fault (Servotronic system not being activated straight away). After a couple of miles, I tried a restart of the ignition and it seemed fine after that.

    After a quick Google search, it appears someone on VW Audi Forum had similar problem but no answers their either unfortunately.
     
  11. A4_MaJiK

    A4_MaJiK Azeem

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    Still no fix for this issue and it is starting to becoming annoying even though I'm quite used to the heavy steering now.

    I tried removing the servotronic relay (ignition off) when the assistance is available (system is warm) and it feels exactly as it does on cold start ups. I may try swapping the servotronic relay with someone else just to see if that either cures the issue or eliminates the fault.

    If anybody around the Leicester area has servotronic and is willing to help me out a bit here let me know please, much appreciated.

    Azeem
     
  12. gruf

    gruf Member

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    have you tried changing the fluid, it might have condensation or water in it, it might look good and at the right level, that dont mean its good.
     
  13. A4_MaJiK

    A4_MaJiK Azeem

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    No because the issue occurred after I had the PAS pump replaced (assuming all fluid was replaced) on warranty in August 2012 as it was squealing on full lock. My two month warranty (from trader I bought it off) expired so I could no longer pursue this issue.

    Is there any way for testing for moisture in the fluid?
     
  14. gruf

    gruf Member

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    I’m sure the law is 3 months on warranty, that’s never here nor there now.

    i couldn’t tell you about testing for moisture someone might be able to help more than me for that issue.
    A lot of the time people who have no interest in your car have more interest in their pocket so maybe they never changed the fluid maybe they topped up with cheap stuff or maybe they emptied out and put back in the old stuff, I’m not saying i know anything but it could be worth getting the right gear and changing the whole lot.
    Now days with minerals and all the specification’s it might be something that’s not meant to be in your car, it could of damaged a seal or a grommet or a valve of some sort inside the pump or rack, it could be loads of things, usually the fluid goes grey when there’s a problem.

    Either way i would change it for the right fluid and go from there.
     
  15. A4_MaJiK

    A4_MaJiK Azeem

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    I bought it off an Audi specialist so I assumed they used the correct stuff (hope they did anyway). For the sake of 2-3L of PAS fluid I may just do that.

    Anybody have any advice on replacing the fluid. I have a vacuum pump and a siphon pump at hand to help. I'm thinking of sucking it all out from the reservoir whilst the engine is running and then have someone turn the engine off as soon as the pump runs dry. Then refill the system with fluid, start the engine and let the pump run for a bit and keep topping up the level as required.

    Thanks in advance,

    Az
     
  16. gruf

    gruf Member

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    i did that on a few of my cars before,
    i think my mate took off the return that goes back to the fluid bottle/reservoir and poored the new fluid into the reservoir and kept topping up while i turned very slowly from side to side on full lock, i never did but he said we should do it agian in a month or so to make sure we got as much of a clean out as possible.
     
  17. A4_MaJiK

    A4_MaJiK Azeem

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    That sounds like a much better idea actually as the pump won't run dry then. I think I'll put a hose on the return to drain it and keep topping up fresh fluid while the pump runs. How long did it take you to drain all the old fluid out and how much of it did you drain out before you reconnected the return i.e. how much fluid does the PAS system take?.
     
  18. gruf

    gruf Member

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    cant remember, the last audi i had was about 4 years ago and my x5 aint the same, if you ring audi parts they will let you know exactly the amount you need.
     
  19. A4_MaJiK

    A4_MaJiK Azeem

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    So I flushed the PAS fluid the other day and it has made it slightly easier but hasn't sorted the issue out.

    After doing some reading...there is a solenoid valve (this is pulsed from the 640 control module in the relay box) to control the boost. There is also a strainer located at the solenoid valve. The fact that the boost works when engine/fluid temperature is warm suggests perhaps the strainer is contaminated/blocked and only allowing sufficient pressure through the servotronic system when the fluid is viscous enough to pass through the strainer with ease?

    Here is an exploded view of the servotronic steering box in question:
    servotronic steering box: exploded view

    [​IMG]
    1. Power steering box with track rodsExploded view for LHD/RHD vehicles
    2. Electrical connector for servotronic solenoid valve -N119-Fitting location: In wheel housing (front left)
    3. Relay carrier, 9-positionLocated underneath trim in driver's footwell Current flow diagrams, Electrical fault finding and Fitting locations
      servotronic control unit -J236- , position 2
    4. servotronic solenoid valve -N119- with integral moulded connecting cableSteering box must be removed in order to renew servotronic solenoid valve
      Do not slacken Torx bolts
    5. Adapter cable
    6. Hexagon socket head bolt, 3 Nm2.5 mm
      Do not slacken Torx bolts
    7. servotronic solenoid valve -N119- with plug connectorSteering box must be removed in order to renew servotronic solenoid valve
      Do not slacken Torx bolts
    8. SealAlways renew
    9. SealAlways renew
    10. StrainerAlways renew
     
  20. gruf

    gruf Member

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    Good bit of homework if your right, i don’t know where the parts are located on the car but if there not that hard to get to it looks like it can be a fairly easy fix if all goes well.
    I’m not a pro but by the sounds of it your rack or pump must be on the way out, that’s what i was saying earlier about the fluid turning grey, it’s because there’s metal grinding away in the pump or rack.
    Maybe have a good flush through while the parts are off to see if any remaining bits come out where the filter does its job.
    Don’t take what i say as gospel though; you don’t want to damage anything.
    Ring a power steering place and ask if they think it’s a good idea.
     
  21. Steve220

    Steve220 Member

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    It would seem to be that this is an electrical issue, not hydraulic. The system physically isn't firing up under load so no matter how much you 'flush' the system, its not going to fix it unless you've got the route key source. You need to know if that solenoid is firing, there's 2 ways of doing this, either check for a voltage over the pins on the plug when the car starts up and runs, the other is to physically feel the valve, a solenoid will make a positive knock when it moves.
    Does anyone know what starts the system up? IE are there any other sensors in the system?
     
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  23. A4_MaJiK

    A4_MaJiK Azeem

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    The PAS pump was replaced under warranty last August due to a squeal on full lock, so I would of thought it was highly unlikely the pump was at fault. The fluid was not in too bad of a condition when I replaced it, just seemed darker than the usual green.

    I believe the rack requires removal to remove the solenoid/strainer from the system and I hear this is a pig of a job to do as well.

    The solenoid is definitely firing as after a restart when the engine/fluid is warm the servotronic functions perfectly fine. It is only if I leave the car for a couple of hours and return that it will fail.

    Funny you should mention the voltages etc. as last night I performed a few diagnostic tests with a multimeter where the control module (pictured below) sits in the relay junction box.

    [​IMG]

    As I performed these checks after I got home from work last night, the car was warm so the servotronic would function correctly if I was to start it up.

    Firstly, I removed the control module and checked for supply voltage to the module on ignition which should have been ~12V. Supply Voltage = ~14.5V

    Secondly, I checked the resistance across the pins going to and from the solenoid on the rack. The resistance should have been between 5-20 Ohms. Solenoid Resistance = ~8.2 Ohms.

    I also noticed that when starting the car on removal of the control module, the steering would have the same feel as it does with the module normally connected on cold start. I reconnected the module with the engine running (probably not advisable and yes I understand the risks involved in this) and the steering assistance was back again.

    I can't really come to conclusion off all of this and perhaps I should try doing the same tests on a cold start condition (perhaps solenoid resistance short circuits or supply voltage isn't available in this condition). It may also be the control module itself at fault, but I can't understand why that would be temperature/condition related as it functions perfectly fine under certain conditions.

    Thanks for taking the time to read guys and I really do appreciate your input. Really want to get down to the bottom of this, the worst thing is that I have not yet come across anybody or something online who are in the same situation so it's good to see your interest in this issue.

    Thanks again,

    Azeem.
     
  24. wyliss

    wyliss Member

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    I know it may be a long shot but have you tried disconnecting/connecting the battery quickly?
    I have a headlamp wash warning the other day and the washers worked. I did the above and all ok now.
     
  25. A4_MaJiK

    A4_MaJiK Azeem

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    I did read somewhere where someone had an electrical issue they disconnected and reconnected the central electrics module which resolved the issue. I guess disconnecting the battery would have the same effect as it will allow all of the modules in the car to power down.

    I will give it a shot when I get a chance and let you know. Worth the try and thanks for the suggestion.
     
  26. jdp1962

    jdp1962 Grumpy Old Moderator
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    It certainly would be good if you could get to the bottom of this; it's been exercising you for months, hasn't it?
     
  27. A4_MaJiK

    A4_MaJiK Azeem

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    I would really love to get to the bottom of this and yes since August last year LOL. I do like a challenge but this looks like it'll turn out to be a bit of an expensive fix. :shrug:
     
  28. A4_MaJiK

    A4_MaJiK Azeem

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    Just an update, on a little experiment I carried out last night after I finished work (Coventry). The ignition was not cycled at any point during this experiment and the engine was running continuously.

    Upon startup (as expected) steering assistance was not available. I drove around a mile away from work (engine coolant was up to 60-70'C) and removed the servotronic module and reconnected it a few times to see if steering assistance would return, but no luck there.

    I then drove back home (27 miles) and whilst the engine was still running (ignition has not turned off yet) removed the servotronic module and reconnected it and voila! Steering assistance was back to normal.

    This concluded that it is not an ignition related problem and leaning more towards temperature related.

    I am thinking of removing the module overnight and keeping it in the house (perhaps near a radiator) and then plugging it in before startup to see if it cures the problem.
     
  29. gruf

    gruf Member

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    maybe you need a new module
     
  30. Steve220

    Steve220 Member

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    Just thinking the same thing! It's definitely point that way.
     
  31. gruf

    gruf Member

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    See if there's one you can swap with a friend to see if it works from cold.
    in the picture it looks like a relay, maybe a module is a fancy name for a relay.
    if its a relay then they often break down bit by bit then one day they done work no more
     
  32. A4_MaJiK

    A4_MaJiK Azeem

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    I understand it looks like a relay, but it is definitely a module. See here for more information. The link shows the same modules, but they are off the A6/A8 (different part numbers). Also these are the only ones I can seem to find on eBay. I'm quite confident they will still work on my car, but I would rather swap with someone else first just to be sure.

    Anybody near the Leicester area who has an Audi with servotronic in the Leicester area please let me know if you are willing to volunteer LOL :thumbsup:

    Hopefully we will get to the bottom of this one very soon!
     
  33. A4_MaJiK

    A4_MaJiK Azeem

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    Another update as we get closer and closer to solving the issue (hopefully). As you all may be aware it was a nice sunny day yesterday (14'C) when I went to get into the car after it had been sitting for around 8 hours. Noticed how warm it was in the cabin (greenhouse effect) and when I started the car...the servotronic worked perfectly first time!

    I'm now 80% sure (hope I'm right) that the module is at fault and only operates correctly when the cabin temperature is above a certain level. Probably something to do with the circuitry within the module if this is the case.

    Looking for a used module in the meantime. Haven't come across anything with the same part number yet but may take a shot at buying one of the many A6/A8 modules from eBay and hoping they work.
     
  34. jdp1962

    jdp1962 Grumpy Old Moderator
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    Morning, A4_MajiK,

    Fingers crossed a change of module will finally crack the case. Have you considered what you will do to fill your time when this is fixed? You might have to take up a hobby.
    :beerchug:
     
  35. A4_MaJiK

    A4_MaJiK Azeem

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    Morning JDP,

    hahaahahaha :uhm: good point though, I've been on this for quite some time now. Luckily I have some patience and I don't give up quite that easily. Everybody kept suggesting taking it in to Audi. But the way I see it, I would have spend hundreds by now as they probably would start replacing components one by one (pump, rack etc.) while I sit back and foot the large bill for the "free" courtesy car they offer me to drive around in. Also there's something rather satisfying when you resolve your own issue based on research, information and suggestions from people such as yourself on here (hence all the updates).

    I did want to continue with the modding the car actually but this issue has been on the priority list for quite some time now lol. Pair of B5 front perches came through the post yesterday (£30 from a member on here actually) and looking into a set of lowering springs to fit at the same time (heard it improves ride quality, handling and also looks much nicer). See here if you wish seeing as nobody has replied yet haha.

    Az
     
  36. jdp1962

    jdp1962 Grumpy Old Moderator
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    Nice one, Az. By the way, I lowed mine last year (more accurately, I paid my local garage to lower it - I am aa complete clutz with anything more complicated that the oil level and tyre pressures). I used Eibach springs from DPM Performance.
     
  37. A4_MaJiK

    A4_MaJiK Azeem

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    Was that the 30mm kit by any chance and did you change to B5 perches at the front? If you've got any pics it would be great if you could post them in this thread.
     
  38. jdp1962

    jdp1962 Grumpy Old Moderator
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    30mm drop both ends, front end perches not changed. Just the one pic, and it's here.
     
  39. A4_MaJiK

    A4_MaJiK Azeem

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    UPDATE: Got the car back from detailing yesterday (looks fantastic now) and the module I got off eBay (from an A6) has been waiting to get fitted since last week. Fitted the module yesterday and the steering assistance seems to be working fine. Although the real test was when I got into the car this morning, as that was when the problem would arise with the previous module. To my surprise, the new module worked perfectly! So I'm pleased to report so far so good...

    I'm not sure what the issue was with the previous module but the new module's assistance characteristics behave very differently (maybe this is how it should have been with the previous module). The previous module would give a light steering feel pretty much all of the time whereas the new module is light <5mph and becomes heavy >20mph (I prefer it this way anyway). Perhaps the previous module was going open circuit when it was functioning and in turn offering full assistance ALL of the time. I wouldn't of thought the A6 modules would behave so differently to the A4 as the cars are not that greatly different from each other.

    So I wanted to ask (for those of you who have Servotronic). How does it behave in comparison?

    Hopefully this has finally sorted the issue out for good (after all that messing about) and I don't need a new steering rack after all. Thanks for all of those that helped contribute their ideas, suggestions and advice (much appreciated).

    Azeem.
     
  40. NHN

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    Just remember some modules need calibrating when fitted, not saying yours does, but if its different it maybe because its working correcly or it requires calibrating.

    Also your module superseded to an F version incase you didnt notice, as didnt read that in the thread yet.
     
  41. A4_MaJiK

    A4_MaJiK Azeem

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    I'm getting quite accustomed to the new steering feel, although I think it should get heavier slightly later (15mph as opposed to 10mph). Do you know the procedure for calibrating the module or if it is even possible on my module?

    Thanks, Az.
     
  42. NHN

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    Thats something audi would do tbh if its possible on that module, you could contact Ross-tech if you have genuine cable, to ask.
     

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