[nastynick83]

All,

I've recently bought a 420d Gran Coupe (F36) 2016 after a 3yr gap from BMW (went to a Tesla M3 P, which was awesome but wasn't doing the miles).

I've had several BMWs in the past; 330xd, 420d, 120d, 116ed but this one doesn't feel 'right' in the steering department...

The easiest way I can describe it is that the power steering is inconsistent and almost goes to sleep. When driving on a straight bit of road it's fine - but then as you start to apply steering input there's an initial resistance and then it's not smooth - think notchy. Then in contrast, when you are driving on a twisty road, the steering feels exceptionally light as though the power steering is working on overdrive.

Tyres are standard fit, Potenza's with >5mm tread and 31psi (tried different pressures too).

Anyone got any ideas? It's in BMW on Monday for EGR recall (software update).

Nick

[Markos ZimZimma]

Originally Posted by nastynick83

All,

I've recently bought a 420d Gran Coupe (F36) 2016 after a 3yr gap from BMW (went to a Tesla M3 P, which was awesome but wasn't doing the miles).

I've had several BMWs in the past; 330xd, 420d, 120d, 116ed but this one doesn't feel 'right' in the steering department...

The easiest way I can describe it is that the power steering is inconsistent and almost goes to sleep. When driving on a straight bit of road it's fine - but then as you start to apply steering input there's an initial resistance and then it's not smooth - think notchy. Then in contrast, when you are driving on a twisty road, the steering feels exceptionally light as though the power steering is working on overdrive.

Tyres are standard fit, Potenza's with >5mm tread and 31psi (tried different pressures too).

Anyone got any ideas? It's in BMW on Monday for EGR recall (software update).

Nick

Doesn't sound great, is it worth asking BMW about it on Monday? They might want +/- £200 for a diagnosis. Presume all BMWs of that age have electronic steering (bar M cars) so it could be software related perhaps.

[Abzynthe]

Maybe it has variable sport steering or servotronic steering?

[johnung]

Originally Posted by nastynick83

All,

I've recently bought a 420d Gran Coupe (F36) 2016 after a 3yr gap from BMW (went to a Tesla M3 P, which was awesome but wasn't doing the miles).

I've had several BMWs in the past; 330xd, 420d, 120d, 116ed but this one doesn't feel 'right' in the steering department...

The easiest way I can describe it is that the power steering is inconsistent and almost goes to sleep. When driving on a straight bit of road it's fine - but then as you start to apply steering input there's an initial resistance and then it's not smooth - think notchy. Then in contrast, when you are driving on a twisty road, the steering feels exceptionally light as though the power steering is working on overdrive.

Tyres are standard fit, Potenza's with >5mm tread and 31psi (tried different pressures too).

Anyone got any ideas? It's in BMW on Monday for EGR recall (software update).

Nick

With steering symptoms on the F3x always check the big cylindrical bushings on the front upper control arms. See photo. They're big oil filled rubber things. They leak if they are shot. Replace the pair of control arms with aftermarket like Lemforder.

People think the electric steering is to blame for the F3x vague steering but it's mostly these bushings.

[nastynick83]

Originally Posted by johnung

With steering symptoms on the F3x always check the big cylindrical bushings on the front upper control arms. See photo. They're big oil filled rubber things. They leak if they are shot. Replace the pair of control arms with aftermarket like Lemforder.

People think the electric steering is to blame for the F3x vague steering but it's mostly these bushings.

Brilliant - thank you! I will take a look (read: ask BMW to take a look on Monday)

Nick

[nastynick83]

Originally Posted by Markos ZimZimma

Doesn't sound great, is it worth asking BMW about it on Monday? They might want +/- £200 for a diagnosis. Presume all BMWs of that age have electronic steering (bar M cars) so it could be software related perhaps.

I'm a glass half-full, kinda guy and did think whether software may resolve, which is what I believe the EGR recall is going to do.

Agree with the plan on asking BMW to investigate by throwing money at the problem. Was keen to see if anyone else experienced something similar to help point BMW in the right direction

Nick

[HighlandPete]

Originally Posted by nastynick83

The easiest way I can describe it is that the power steering is inconsistent and almost goes to sleep. When driving on a straight bit of road it's fine - but then as you start to apply steering input there's an initial resistance and then it's not smooth - think notchy. Then in contrast, when you are driving on a twisty road, the steering feels exceptionally light as though the power steering is working on overdrive.

Anyone got any ideas?

That's a strange set of symptoms.

In a straight line, there is no power to the rack. Only when the torque sensor is 'loaded' does power get applied. Notchy, could indicate erratic assistance. Then the light feeling through the 'twisties'... appears over assisted.

I wonder if the torque sensor is playing up.

Couple of thoughts which may give more clues... does it behave same/different in Comfort vs. Sport mode? (Ensure chassis/steering is checked).

Does it respond differently, if the steering input is gentle, compared to quick more aggressive inputs?

[johnung]

Originally Posted by nastynick83

Brilliant - thank you! I will take a look (read: ask BMW to take a look on Monday)

Nick

Just to give you an idea of cost, see photo. The name brand aftermarket companies like Lemforder, TRW, Mehle, make them for BMW and are less than half the price of Genuine BMW. An independent BMW shop shouldn't charge more than 2 hours labor to install a pair.

[nastynick83]

Originally Posted by HighlandPete

That's a strange set of symptoms.

In a straight line, there is no power to the rack. Only when the torque sensor is 'loaded' does power get applied. Notchy, could indicate erratic assistance. Then the light feeling through the 'twisties'... appears over assisted.

I wonder if the torque sensor is playing up.

Couple of thoughts which may give more clues... does it behave same/different in Comfort vs. Sport mode? (Ensure chassis/steering is checked).

Does it respond differently, if the steering input is gentle, compared to quick more aggressive inputs?

I'm finding it hard to describe the symptoms other than 'it doesn't feel right'...

It behaves the same when in comfort or sport - the latter just being slightly heavier steering (but still gets un-naturally light when used).

When steering gently - example, making small corrections to steering while on a motorway - you go to make a slight steering adjustment and there's the initial resistance. So it feels like you can never make a small adjustment smoothly without having to apply more force than expected.

When steering more aggressively - this is when the steering starts to get exceptionally light and just feels completely disconnected from the road. Example a drive on a B-road with lots of bends.

So it feels like when doing small movements less frequently that it's gone to sleep but when steering actively that it's on overdrive.

I'd point the finger at the power steering - not giving consistent power assistance?

Nick

[Wibbles]

It's likely to be the SZL that is at afault - I had the same symptoms on an M135i with variable sport steering - basicaly the steering angle sensor is at fault, so the car's ecu's cannot detirmine how much assistance to give.

Swap out the stalks, which contains the SZL and see if it makes a difference.

[MY340i]

Hi Nick,

Let me know how you get on with this as have it on my car and its driving me mad. I've done the following so far

1) changed tyres and tyre pressures

2) Hunter alignment and tracking done

3) EPS software update as there were some technical bulletins saying this could solve it

4) had suspension visually checked, no obvious issues

5) diagnostics ran on car, no obvious issues.


looking to be either one of three things:
1) new SZL
2) Steering rack is on its way out, in which case it will need to be replaced.
3) full suspension refresh, ARB etc.

[MY340i]

Originally Posted by Wibbles

It's likely to be the SZL that is at afault - I had the same symptoms on an M135i with variable sport steering - basicaly the steering angle sensor is at fault, so the car's ecu's cannot detirmine how much assistance to give.

Swap out the stalks, which contains the SZL and see if it makes a difference.

Hi wibbles - this could very much be the case with mine, as my steering is much like that is described above.

But nothing showing on diagnostics atm.

I had intermittent cruise control failure, and the local indi changed the wiring harness and that seems to have resolved it.

They said if error comes again then the SZL will need to be changed which is coming to £450 + Vat + fitting + coding. does this sound about right?

[Wibbles]

Originally Posted by MY340i

Hi wibbles - this could very much be the case with mine, as my steering is much like that is described above.

But nothing showing on diagnostics atm.

I had intermittent cruise control failure, and the local indi changed the wiring harness and that seems to have resolved it.

They said if error comes again then the SZL will need to be changed which is coming to £450 + Vat + fitting + coding. does this sound about right?

CC failure is another symptom because the CC uses the steering angle sensor.

Mine did not show up on any diagnostics either, I only found out that was the issue when I retrofitted a heated steering wheel and needed to swap out the stalks and SZL for a different part to suit the new wheel.

Price wise, you could fit and code that yourself for £100 - depending on part cost for a used SZL.

[MY340i]

Originally Posted by Wibbles

CC failure is another symptom because the CC uses the steering angle sensor.

Mine did not show up on any diagnostics either, I only found out that was the issue when I retrofitted a heated steering wheel and needed to swap out the stalks and SZL for a different part to suit the new wheel.

Price wise, you could fit and code that yourself for £100 - depending on part cost for a used SZL.

nice one thanks. Good to know a used SZL can be used.

Infact I've just taken the 340i for an extended test drive, first time since getting it back from the steering wheel loom being replaced.

Seems to be behaving properly now. Not sure if its resolved, or maybe just a placebo effect in my head, but steering now feeling good again.

[Wibbles]

The SZL is not VIN locked and does not need coding as such - the steering angle sensor can be reset with diagnostics but if you purchase a used part with the same part number as the one on your car, will be plug and play

[HighlandPete]

Originally Posted by Wibbles

Mine did not show up on any diagnostics either, I only found out that was the issue when I retrofitted a heated steering wheel and needed to swap out the stalks and SZL for a different part to suit the new wheel.

Price wise, you could fit and code that yourself for £100 - depending on part cost for a used SZL.

Not following how the SZL is linked to the steering issues posted above, as the F3x models with their EPS, don't have a conventional steering angle sensor.

The steering angle sensing is performed from within the rack, using motor position.

The information on the steering angle in the F30 is not recorded by the Electronic Power Steering EPS via a separate sensor on the steering wheel and instead is computed based on the angle of the EPS motor position in relation to the steering wheel.

New: The rotor position sensor is at the same time the steering angle sensor.

The EPS does not determine the steering angle using a separate sensor on the steering wheel. Instead, the EPS unit determines the steering angle from the motor position angle of EPS unit motor on the steering wheel. The EPS sends the rack position to the ICM control unit via FlexRay. To do this, the EPS calculates the absolute position of the rack from the current rotor position of the servomotor and from the number of complete rotor revolutions from the neutral position (i.e. straight-ahead driving position).

[Wibbles]

The SZL also feeds it's info into the ICM and is used in conjunction with the rack.

Where have you taken that information from ISTA/NewTIS?

[HighlandPete]

Originally Posted by Wibbles

The SZL also feeds it's info into the ICM and is used in conjunction with the rack.

Where have you taken that information from ISTA/NewTIS?

BMW training and NewTIS. Same for other models like the F10 5-series.

I agree there may be a data transfer from the SZL, but it is not a SAS as the older HPAS systems.

[nastynick83]

Originally Posted by MY340i

Hi wibbles - this could very much be the case with mine, as my steering is much like that is described above.

But nothing showing on diagnostics atm.

I had intermittent cruise control failure, and the local indi changed the wiring harness and that seems to have resolved it.

They said if error comes again then the SZL will need to be changed which is coming to £450 + Vat + fitting + coding. does this sound about right?

What is an SZL?

Nick

[MY340i]

Originally Posted by nastynick83

What is an SZL?

Nick

BMW Steering Switch Unit (also referred to as SZL, center steering column switch, and switch unit in the steering column) is mounted on the BMW steering column where various switches, including a wiper, turn signal, and cruise control, are mounted.

[nastynick83]

Originally Posted by HighlandPete

Not following how the SZL is linked to the steering issues posted above, as the F3x models with their EPS, don't have a conventional steering angle sensor.

The steering angle sensing is performed from within the rack, using motor position.

So if I read that correctly; symptoms could point to needing a new steering rack?

[nastynick83]

Originally Posted by MY340i

Hi Nick,

Let me know how you get on with this as have it on my car and its driving me mad. I've done the following so far

1) changed tyres and tyre pressures

2) Hunter alignment and tracking done

3) EPS software update as there were some technical bulletins saying this could solve it

4) had suspension visually checked, no obvious issues

5) diagnostics ran on car, no obvious issues.


looking to be either one of three things:
1) new SZL
2) Steering rack is on its way out, in which case it will need to be replaced.
3) full suspension refresh, ARB etc.

Glad that I'm not going crazy and others have had similar issues. I'm also impressed you understood my symptoms from my description.

I'll keep you posted.

Nick