help! Random Power Steering

[Anonymous]

Dear Forum,

I've been enjoying my Z4 (2005 55 plate 3.0i SE) for couple of months and have been experiencing the 'sticky' steering so widely discussed. This has now developed into the fault light and it turning off every time i hit the lock stop, or even randomly mid roundabout.

I've had a friend do a diagnostic and it's flagged no codes.

Seems to be worst turning right (i.e. most frequent). That said, it is possible to drive it (mainly 'faster' so less resistance) for a good period, but inevitably you have to do a tighter turn and *boing* there it is again

Before I spend £2k on a new column is there anything else it could be? (i.e. battery low, steering rack, motor etc)

All helpful suggestions welcome so I can enjoy the car and my commute again!

 

[Drshemming]

No codes seems a bit strange, what system was used to carry out the diagnostics?

 

[wowser]

i feel for you, lots of us are having the same problem. Its probably going to get worse over the next few weeks with the warmer weather.

My steering does the same thing, also on right hand lock!!! i bought a scanner off ebay, on OBD 11 recommended on the forum, and it doesnt pick up any codes. However, when i have had it scanned on a flash jobby that goes into all the modules individually, same sort of thing BMW use, it picks up the "steering torque sensor".

Cures?? try lubricating the UV joints for the steering under the engine bay. There are two, one that comes out of the firewall, left hand side, and follow it down, and you will find another right under the engine and exhaust. I think this is the joint at fault. You may need a high temperature grease, and repeat regularly as it will dry out. Too much heat, expands the parts, causing too much friction, and the torque sensor detects too much or not enough voltage to send through the EPS module, so shuts it down to be safe.

I have found that if your EPS light is always on, when u starts the car up, hold the steering wheel slightly locked left/right as the steering lock disengages, and hold it in the same position for a few seconds. Then slowly move the wheel left then right, and usually sorts everything out.

Another tip, in hot weather, try driving with your air con on coming through the dash vents and a bit through foot well, to help cool everything. The fault may be lying in the upper steering column. Noone seems to have got to the bottom of this fault yet, but keep everyone posted on your progress.

 

[Stuart Truman]

No code on mine either. BMW swapped the column under warranty.

The standard symptom is that it feels like the power steering has paused and then wakes up, rather like someone is preventing you steering and then lets go, hence sticky.

There are two schools of thought that seem most plausible. One is the steering ECU overheating (and this is the one I subscribe to) and the other is an internal bearing failing. It is of course entirely possible that both give similar symptoms.

Good luck with it. Having experienced the cost of this little foible, I'd recommend anyone to have a warranty

 

[haKKaMeE]

Hi Guys

Good morning. I'm Maverick from Malaysia and i'm facing the same problem too. Have anyone try out wooser solution. My ride is at the workshop now. I will shall keep you all posted. Thanks.

I just changed a second hand steering column 3 months ago now the next problem is steering tourque sensor.

Regards
Maverick

 

[wowser]

There are only two sensors on the steering column. Steering angle sensor and steering torque sensor. The steering angle sensor is more prone to malfunction when you have bad alignment or traction control issues. The torque sensor will come up on your scanner for various reasons: to high/low voltage output to protect the ecu from
Varying voltage outputs. Too high temperature, or a fault in a module. Have a good
Look at this workshop manual:

http://www.bmwclub.lv/files/06_E85_Chassis_Dynamics.001.pdf

Scroll down to the steering bits. Quite a lenthy bit on everything to do with the steering column. Its is quite easy
to understand, and also tells you about installing and working on a replacement column.

 

[wowser]

U have to get a top notch scanner to be able to access the EPS module codes. If your light has gone off for power steering a fault code will be stored

 

[Anonymous]

Well chaps, it got worse and I basically had no power steering.

So I called in to MTek in Northampton and I was diagnosed with a failed Torque Sensor.

Having now spent just over £2k (inc VAT) to have a new column (£1,471 + VAT from BMW) all is well and I am assured by Ian at MTek that this should also resolve the sticky steering as they have changed the design slightly.

MTek and I were both amazed by the size and extent of what has to be replaced and the size of the steering motor.

All I can say is that it was a painful experience. Lets hope that the rest of the systems stay on line....

 

[haKKaMeE]

Hi Brickebrownie

I'm having the same problem like you. How your mech confirm its a failed Torque Sensor. Am having the same problem with popped out EPS sign from dashboard. Scanner also indicate steering torque fault.

Meaning a brand new steering column will solved this issue. Please advise. Thanks.

 

[Ewazix]

There are only two sensors on the steering column. Steering angle sensor and steering torque sensor. The steering angle sensor is more prone to malfunction when you have bad alignment or traction control issues. The torque sensor will come up on your scanner for various reasons: to high/low voltage output to protect the ecu from
Varying voltage outputs. Too high temperature, or a fault in a module. Have a good
Look at this workshop manual:

http://www.bmwclub.lv/files/06_E85_Chassis_Dynamics.001.pdf

Scroll down to the steering bits. Quite a lenthy bit on everything to do with the steering column. Its is quite easy
to understand, and also tells you about installing and working on a replacement column.

Interesting! If I'm reading P14 correctly it may hint at the answer then? the Electronic Power Steering (EPS) module heats up when in use and is designed to shut down intermittently when it overheats. Dealing with high torque inputs due to stiff steering components like the column bearing and lower UJ's will require more from the EPS, and presumably more likelihood of an overheat? This could explain why high ambient temp sets off sticky steering, and how lubricating components seems to reduce but not always eliminate the problem. The EPS is also voltage sensitive which could account for why some have cured apparent sticky steering by replacing a failing battery.

Fortunately mines still behaving fine even when left in the sun all day :|

Any thoughts on the viability of fitting a small cooling fan on the EPS module, I'm wondering about something like those fitted in a desktop PC ?

 

[wowser]

yep you've hit the nail on the head very hard!!!!

People are replacing the steering columns because of a "faulty torque sensor". Theres nothing wrong with it, its just doing its job in monitoring everything within the EPS module.

I just come back from a 230 mile drive from south wales to doncaster. I lubricated my steering joints prior to leaving, and this does help your sticky steering issue. However, as you said the EPS shuts down when it gets hot. Sometimes the power steering shuts down by 50% as it says in the manual (as it is designed to do). This 50% could be another issue with the stickiness where the power steering suddenly wakes up.

I have found that if you drive with your air con on for a few moments, and set it to come out of the dash vents, it will cool the whole of your dashboard. The aluminiun plate on your dash will be really cold to touch, and then you will know your electrics inside the EPS module should be cold.

It is a design fault, but there is no need for column changes straight away i dont think. My eps was going off every week. Now its more like every 3 months when i started lubricated the UJ's. More recently has gone off in god knows how long. The hot weather will dry out the lube, so you will need to repeat the process. Also in the winter, freezing cold weather may have a waxy effect on the lube as well, plus all the crap from the grit on the roads may dissolve it.

 

[bcworkz]

People are replacing the steering columns because of a "faulty torque sensor". Theres nothing wrong with it, its just doing its job in monitoring everything within the EPS module.

What makes you so sure it's not the torque sensor? I think you're possibly right, I'm only asking for the sake of discussion. Why would the EPS module report torque sensor issues unless there was something wrong with the signal it's receiving? In every other diagnostic situation of sensor vs. processor, it's the sensor that's invariably at vault.

Some will say what difference does it make, you have to replace the entire column either way. It does look likely it would be very difficult to change the torque sensor, but the control module is probably just an electronics can screwed to the side of something and could be exchanged. Just because it's not listed as a separate part doesn't mean it couldn't be exchanged, from off of a breaker's vehicle for example.

 

[Ewazix]

People are replacing the steering columns because of a "faulty torque sensor". Theres nothing wrong with it, its just doing its job in monitoring everything within the EPS module.

What makes you so sure it's not the torque sensor? I think you're possibly right, I'm only asking for the sake of discussion. Why would the EPS module report torque sensor issues unless there was something wrong with the signal it's receiving? In every other diagnostic situation of sensor vs. processor, it's the sensor that's invariably at vault.

Some will say what difference does it make, you have to replace the entire column either way. It does look likely it would be very difficult to change the torque sensor, but the control module is probably just an electronics can screwed to the side of something and could be exchanged. Just because it's not listed as a separate part doesn't mean it couldn't be exchanged, from off of a breaker's vehicle for example.

Interesting points, but my take on this is that neither the torque sensor or the EPS are necessarily 'faulty' as such, the EPS is designed to cut assistance when it overheats or the voltage supply is out of range - it seems that the EPS heats up the harder it works and high ambient temperatures and resistant steering components compound the problem, so maybe a design fault rather than a faulty component?

Hence my wondering about the viability of fitting a small PC style cooling fan on the EPS module, I'm no electronics boff but assume it must be possible, although I've no idea if would do any good?

 

[gtturbo87uk]

I have the exact same fault on mine, but i have never had the notchy feelin. My fault is definatly not affected by temperature so a cooling fan would not hrlp. Sometimes it happens from cold start, other times whilst i have already done a few miles. It also does the same on full lock, and my friends snap on fault code reader shows nothing.
The more i read about this problem it seems fitting a new column is the only option. I have scanned loads of breakers and no one seems to have a secondhand column. I dont have £2000 to shed out, there must be someone who repairs the columns. Ecu's are repaired and alot of other electronic componente why cant the same be done with this?
I have read what people say abot the torque sensor if this was the case on mine can these not be purchased on their own then fitted?

 

[wowser]

In most cases sensors are at fault. However the torque sensor controls so many things in the EPS module. It is doing what it is designed to do i guess.

You wouldnt replace the oil level dipstick sensor, just because your low on oil would you?? You just top up the oil, wait for sensor to turn off and carry on.

The torque sensor is very difficult to replace. Its a small magnetic device, and upper column has to come out. May as well just look for a breakers oart.

Even though your light may come on only after a few miles, you got to survey what conditions there are. Is the weather boiling hot, or are your heaters on warm,

Its clearly a design flaw, and a complete pain in the ass. Bring back hydraulic racks anyday!!

 

[gtturbo87uk]

In most cases sensors are at fault. However the torque sensor controls so many things in the EPS module. It is doing what it is designed to do i guess.

You wouldnt replace the oil level dipstick sensor, just because your low on oil would you?? You just top up the oil, wait for sensor to turn off and carry on.

The torque sensor is very difficult to replace. Its a small magnetic device, and upper column has to come out. May as well just look for a breakers oart.

Even though your light may come on only after a few miles, you got to survey what conditions there are. Is the weather boiling hot, or are your heaters on warm,

Its clearly a design flaw, and a complete pain in the ass. Bring back hydraulic racks anyday!!

Yes i agree get rid of eps. Do you know about removing the column what should i be careful of as they sound very easy to damage?

 

[bcworkz]

Main thing is the lock pin (1/3 way down page) must be in place anytime the column is moved or out of the car.

Thermal protection does seem to be an issue, but some have had problems when the unit is hardly working, i.e. straight line on the motorway, so I'm not entirely convinced thermal protection is the complete explanation. It's possible different people are having separate unrelated issues that manifest as the same symptoms.

I had a similar cooling idea to the fan, except also adding a Peltier effect chip. The question is, where is the ideal placement of such a device? Or is the problem the whole massive thing getting too hot? It'd take a lot of effort to cool the whole thing, it's massive!

 

[wowser]

i just find it a bit ironic people are having these issues during a warmer period of the year.

Just try driving with air con coming out of dash vents, to keep it nice and cool

 

[Ewazix]

I had a similar cooling idea to the fan, except also adding a Peltier effect chip. The question is, where is the ideal placement of such a device? Or is the problem the whole massive thing getting too hot? It'd take a lot of effort to cool the whole thing, it's massive!

Neat idea, would there be a temp sensor on 'the' critical hot component for the EPS module to know to shut down? if so the measured component must be the target to cool (whatever it is). I've no experience of installing Peltier cooling but what rating/sized Peltier plate may be required to cool a module for example, with a small PC fan.

I havn't got SS issues but it would be interesting to have a defective old column to tinker with just to see if it could be done

 

[bcworkz]

Just try driving with air con coming out of dash vents, to keep it nice and cool

I wonder how hard it'd be to branch a duct to blow directly on the gear housing. Or could just be a matter of cutting a hole in the right place and partly closing the associated vent.