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MG MGF Technical - Easier to steer to left than right

I have a 1999 MGF VVC which has a strange but I have been told, not unheard of, problem with the electronic power steering.

The steering is much lighter to turn to the left than the right especially at low speeds..... it is not really noticaable - at higher speeeds when I guess the power steering turns itself off anyway.

Does anyone know what could the cause of this?

Many thanks in advance,

Shaun
SA Joughin

Just as a quick follow up on this - it does not seem to pull to any side. It is just the physical turning of the steering wheel which is easier one way than the other.
SA Joughin

EPAS problems are over all extremely rare, but the problem you're describing is being reported increasingly frequently (or it seems that way to me anyway!)

The problem when this happens is a problem with the torque sensor. Have a look through the archives for more. In fact, Darren is looking at this as well if you look at the other thread on steering and 'torq')

The steering column, where the sensor and assistance motor is located, is a non-service item - which means that if you go to a garage, they'll simply replace what you have. However, there are a few specialist centres that can sort this problem out.

If you are very mechanically handy, you may be able to strip the steering column and make the necessary adjustments...

Hope you get this solved soon!
Rob Bell

Try jacking up the front of the car, so both front wheels are off the ground. Set the steering to straight ahead and then turn on the engine. If the sensor is maladjusted the steering wheel will try to turn left by itself. Another quick test is to start the car and see if the steering wheel jumps to the left slightly as the EPAS light goes out and the EPAS comes in.

Adjusting the sensor is not a hard job but getting to it is.

You can adjust it by trial and error by marking the sensor with paint (as you don't want to loose the original position of the sensor) and turning it very slightly until the wheels don't turn left by themselves or if your electrically minded measure with a digital multimeter.

Good luck.
Keith

>> or if your electrically minded measure with a digital multimeter. <<

Is this the method you used Keith? I presume that the resistances alter according to position?
Rob Bell

My 2005 MY TF is going back to B&G on Friday for them to sort this very issue which they assure me is sensor based - Not sure exactly what they are going to do, but certainly involves removing the column!
M19 CPB - Chris Brown

Hi Rob,

Yes, The sensor is effectively a dual potentiometer wired up like so.

ground------XXXXXXXXXXX------+5V
^
+5V---------XXXXXXXXXXX------0V
^
At rest the wiper of each of the potentiometers (indicated by ^ in my diagram) sit at 2.5 volts (half of the supply).

As you pull on the steering wheel and twist the torque shaft the wipers of the potentiometers both move to either the left or right (of the diagram), so one wiper increases in voltage and the other decreases). This is what is fed to the ECU to tell it to drive the motor to assist you in whatever direction you are pulling on the steering wheel.

So that there is no play in the sensor it is spring assisted, and runs on one side of the slot in the torque shaft. Any wear on the torque shaft, potentiometer arm, or movement of the sensor adjustment causes the sensor to go slightly out of position at rest.

Ideally the 2 wipers should each sit at 2.5V when the steering is at rest. So the difference between the voltage at the 2 wipers should be zero and the ECU doesn't fire up the motor. This is what you need to get back to.

To reset mine I unplugged the sensor (connector on the steering column) and connected 5 volts (well 6V, 4x A battteries in series) to the 2 terminals of the connector to the sensor (from memory I think they are black and red wires) and a meter accross the other 2 (going to the wipers).

On mine I found that there was a reading of about 300 millivolts when the steering was at rest (front wheels off ground and pointing straight ahead, no force on the steering wheel).

I adjusted the sensor until the reading on the meter is as close to zero as possible (ideally less than 10 millivolts). I wiggled the steering wheel and repeated the setting procedure a few times until I found the best position for the sensor.

The reason I did it this way was because your working around the fuse panel so best to have the car battery disconnected. By supplying a seperate supply I could set it up without any risk of shorting anything out on the car.

Tips:-

Don't remove the sensor bolts completely just loosen them very slightly, as the spring assistance of the arm of the pot can cause it ping out of the slot in the torque shaft. If you want to replace the bolts make sure you only remove and replace one at a time. If by some chance the sensor arm does pop out, its easy to get back in, just turn the sensor until it pops back into the slot and refit the bolts. When the arm is back in the slot you'll feel the spring assistance as you turn the sensor to align the slots on the sensor with the bolt holes on the mounting plate. If you can't turn it to align the slots your 180 degrees out (trying to turn the arm in the wrong direction) DON'T FORCE IT. Refit the sensor.

There is hot melt glue in the adjustment slots. You have to pick some of it out to be able to adjust the sensor. It's probalby best to replace the glue after youe work is completed.

Paint a mark on the sensor and mounting plate because as soon as you loosen the bolts slightly, the spring assistance will twist the sensor to one end of the mounting slots. The final position will only be slightly away from this mark.

Replace the security torq bolts with ordinary bolts, just in case you ever need to repeat the excercise.

Sorry I couldn't draw anything better.

I hope this is of some use. Its been 2 years since I reset mine and I've had no further problems.




Keith

Sorry, In my last the reply I tried to draw the wipers in the centre of the potentiometers but the posting removed the blank spaces preceeding them. Also for some reason I called labeled the 0V side as ground on one half of the pot and 0V on the other.

Here is another try.

AT REST (both wipers sit at 2.5V)

ground 0V ---------XXXXXXX^XXXXXXX--------+5V
+5V ---------XXXXXXX^XXXXXXX---- ground 0V

TURNING STEERING WHEEL LEFT
ground 0V ---------XXX^XXXXXXXXXXX--------+5V
+5V ---------XXX^XXXXXXXXXXX---- ground 0V

TURNING STEERING WHEEL RIGHT
ground 0V ---------XXXXXXXXXXX^XXX--------+5V
+5V ---------XXXXXXXXXXX^XXX---- ground 0V

Keith
Keith

Excellent post Keith...

As Rob says for some reason this "pulling to the left" problem is being reported more and more on this/other boards lately...

As I understand it MGR allways said the EPAS column was a non-sevicable item and would need replacing if this fault occured!...(but then they would say that!;O) )
IIRC columns would cost around 500 new + fitting so could work out a VERY expensive repair!....

Perhaps you should offer this service to fellow F/TF owners.........could be a nice little earner!! :o))
Mark.L

Rob..

Could you put Keiths solutions on your site??....

Would be most helpfull to post a link to similar threads! :o)
Mark.L

excellent thread there keith. just looking you are not a member??? with that advice i would be matey. rob bell dieter will and keith excellent info all round guys ...

once again great advice going to have a crack at my sensor . i have the right tools now thanks guys on the matter.

darren milton keynes
darren jeffery

Keith, you're a star! :o)

As Mark suggests, I'd love to be able to reproduce this on my site, if that's okay with you?

At some point, I shall check my EPAS out and take suitable pictures :o)

Good luck with your efforts Darren, and let us know how you get on.
Rob Bell

Darren - how's your torque sensor adjustment going? If you're able to, can you take pictures to illustrate Keith's excellent instructions?

Looking at the pictures on Dieter's site, getting to the sensor will be a nightmare - it must be burried inside the fuse box near the transmission tunnel trim... ugh! :o(

Keith, on the torque sensor connector block, how did you connect up your battery and multimeter?

Rob Bell

hi rob not done it as yet been away in london. i will try and get some photos off the torque sensor if i can ... if u email keith put a message to him he might send you some pics and workings....

all the best darren. yep its a struggle have to take out the fuse panel with an 8mm spanner. and work from the side to get to the torques might have a go tomorrow if the weather holds out..
darren jeffery

Sadly, I don't have Keith's email. Keith, if you're reading this, my address is robert dot bell at kcl dot ac dot uk :o)

Fingers crossed for you Darren - the weather in London today is a bit damp, hopefully a bit dryer where you are.
Rob Bell

hi rob send me an email to my private account i will pass it on to keith as he lives in mk as well

anyway done the the sensor today

what a job

disconnected the battery

undone the fuse cowl
to the fuse panel out with a 8 mm spanner and mould grips.

got to the torques damm they where hard to get out.
bought a security torque set,
used attchement t25 and and a screw driver..
got thoses bolts out marked the centre point off the sensor as what keith explained got the melt glue out with a needle screwdriver...
his the fun bit did not jack her up trial and error method which works.
undone the bolts. turned the sensor down a smidge bingo it works put the battery on the steering wheel stays put does not go to the left anymore 500 pounds saving . its a fiddle but it works thanks to keith in mk he popped over explained one cold wed night. and wow shes done ready for the mot in may


thanks to all the guys who gave me help in the matter rob dieter will and keith see you at silverstone event it took a year to do it goes to show put your mind to it and you can save yourself a small fortune

darren
darren jeffery

Hi Darren,

Glad you have got it sorted. "Down a smidge" worked then? I wasnn't 100% sure that it was "Down a bit" but you have now confirmed it.

Keith
Keith

Darren, YHM :o)
Rob Bell

hi rob does that mean yhm you have mail???? if so checked my email nothing at present.
keith is on here so you could speak to him now .

all the best

darren
darren jeffery

Sent yesterday Darren - but will resend again today!

Keith, if you're reading this, drop me an email on the address above :o)
Rob Bell

Hi Robert,

I'm not able to email to you, fails to deliver. Can you confirm your email address please, or email me
keith.starbuck@vodafone.com

Keith
keith

Just sent a mail Keith - hopefully you'll get it shortly :o)
Rob Bell

This thread was discussed between 18/04/2006 and 24/04/2006

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