[SpencerC_6MT]

TL;DR: our EPS's downfall isn't steering weight, or road feel, but wheel weight progression as tire load increases, which I learned by completely disabling power steering

Background:
Last night, I decided to do a little experimenting with my EPS coding, and I discovered why F22 (and likely all F-chassis) steering feels unnatural to seasoned drivers. Although I don't have too many years under my belt, my short experiences with other cars, and understanding of my own, gives my $0.02 a little value.

Max Current:
In ProTool, there's a treasure trove of values at hand to fiddle with, and I stuck to the beaten path at first. Specifically in the EPS section, there are two major settings one can change: max current, and vehicle variant. Max current is pretty straightforward, it's the maximum current allotted to the steering rack. This effectively determines how light the steering can go, and has 4 pre-optioned values: 85A, 85A with tolerances, 105A [default for our cars], and 120A. My first change was to try out 85A, and it added a nice bit of weight to each drive mode. I couldn't easily tell the difference between the "with tolerances" version, but it felt to me like a combination of stock 105A at low speed and heavier 85A at high speed. I stuck with 85A, as the extra weight feels nice, though does nothing for feel.

Vehicle Variant
This next setting is the game-changer though: vehicle variant. Since our cars share a steering rack with a vast major of RWD F-chassis BMWs, the code for all those cars isn't removed from the computers, meaning our cars can use the coding from any of those cars and their subvariants. F30, F33, F25, the sky is the limit. Seeing as our cars are the sportiest on the list though, I stuck to the variants of our default steering default setting "F020_Sport_M135i_Nobuildlevel_Sdrive_Vdc". This also implies the programming is identical to early F20's, a little disappointing as I heard rumors of changes being made for B58 cars. Regardless, the setting I tried out was "F020_Sport_M135i_Sdrive_Vdc", the only difference being that "nobuildlevel" chunk. I figure the xdrive settings would be unlikely to improve anything, and "novdc" settings are likely a marginal change meant for cars without adaptive dampers. Initially, I couldn't feel much a difference (more on that later), but the disappointment of this discovery led me to a strange idea: disabling EPS altogether. Although there's no pre-set option for this, setting a custom value of "FF" seemed to do the trick, as FF is the value for every disabled option I could find in ProTool.

EPS Disabled
Although I've never driven a manual steering car, I can tell you that this is heavier than it should be. Much heavier, dangerously heavy, even at speed. I attribute this to a few factors: first, my 245-section tires on fairly aggressive -2.3 camber. But more importantly, the weight of turning not only the quick-ratio steering rack, but all the associated EPS hardware that usually carries its own weight. For some reference, try turning your steering wheel with the ignition off. This is roughly how hard it was to steering under 10mph, and it only slightly improved as speed increased. I figure the weight would've bled off around 50mph if it weren't for the EPS hardware, which I could still feel the weight of at highway speeds. However, a (difficult) run to my trusty backroad revealed what BMW hides from us. Though initial turn-in takes a manageable force at speed, the wheel gets drastically harder to turn as steering angle increases, and continues to get heavier as force on the tire increased. Although the weight of the steering was unpleasant to say the least, I got very accustomed to using weight through the wheel as a measure of how much the front tires were loaded up, and I experienced a level of confidence through some turns which I had never managed before. This whole process was subconscious though, and my initial relief at the return of power-assist (non-nobuildlevel this time) became a crushing disappointment on the first corner. The tires load up, and nothing. Steering weight is identical past a certain steering angle regardless of lateral-g's. I began pushing harder and harder just to get some feedback, until I realized I was on the brink of understeer with no results. I pulled over to revert to "nobuildlevel" default coding, and despite a slight sensation of tire load returning, you really had to look for it.

Conclusion:
This experiment taught me why, in my opinion, BMW EPS sucks. The feeling of tire load increasing force through the steering wheel is critical to understanding what the car wants to do and how much grip is available, and trying to make this car's front end communicate is like waterboarding a CIA agent; it won't talk to save its life. My hypothesis is that the car is measuring torque at the wheel directly instead of torque at the EPS motor, and attempts to keep torque acting on the steering wheel almost identical across the range of speeds and lateral-g's the car may be acted upon. I believe it would be in the interest of enthusiasts to find a way that we can keep the amount of assist more consistent across the board, rather than allowing the car to compensate for lateral g's with more assist. I still think 85A is a little too light for my preference, though it's certainly an improvement over default.

How-to:
For anyone else looking to play scientist with their cars: be careful. This steering is dangerously heavy unassisted, and your ability to make sharp maneuvers will be severely hampered. Even with some momentum behind you, turning the wheel past 90 degrees is a workout. Don't drive this way on crowded roads, and preferably take a backroad that's less notorious for wildlife mishaps. Now for the settings: in ProTool, select "EPS Coding" in the menu, and set the vehicle variant through "VehicleVariantsTF1Value", "VehicleVariantsTF2Value", and "VehicleVariantsTF3Value". If you want to try "manual" steering as well, use custom value "FF" for these, though you can give any of the 100+ options a shot if you'd like, making sure that the value is the same for all three settings. Read closely, as there are many settings that read similarly but vary by only a few characters. Messing with max current is much easier, simply select that option and choose between the 4 settings. I'd also suggest you try this before anything else, as a frame of reference. When I disabled EPS as a whole, I also set this to custom value FF, though I'm unsure of the effects when you mix and match FF Max Current with regular steering and vice versa. And, as always with coding, be sure your battery has a solid charge and you disable as much accessories as possible to limit drain. People who say you need a trickle charger for this are going over the top, but tread lightly.

P.S: eLSD Disabling
As a little sidenote for people who may want to kill the eLSD: the setting you're looking for is under the DSC menu, in one of the expert-mode submenus (I believe the one at the top of the list). The setting you're looking for is "C_Funktion_Differenzialsperre_aktiv_l" and simply toggle from enabled to disabled. My 6-speed has a Diffsonline Wavetrac unit with 3.46 gears, so it may drive differently from the clutch-type M Performance many of yall likely have (and obviously different from the stock open diff), but in my experience the eLSD disabling is a worthwhile. I'm running the stock tune with a Dinan boost controller on 340tw Continentals, so solid power but nothing wild, and I feel the back is a little more willing to step out now. Where before you really needed to use some weight transfer to kick the back out, it's now more willing to get angle off of torque alone. A little power oversteer takes more work to correct, though it's faster thanks to the computers not dragging on that inside wheel, and sharper angles are able to be controlled by throttle modulation rather than keeping it pinned to the firewall and throwing the wheel around. There's some other DSC functions you may want to investigate in the quest to make your 2-series drive more "naturally", such as Cornering Brake Control, but I've taken up enough of your day already, and I don't have the roads or talent to give you an idea of how these will alter performance in a 10/10th's scenario.

I hope this contributes something to the community knowledge on F22 steering - thanks for reading! Also let me know if a video on the topic would be of interest, I've been thinking about dipping a toe in the video-making sphere.

[Kernel Kurtz]

Excellent post, thanks for that. I've come to the conclusion that it is probably not possible to get the feedback of hydraulic steering with the EPS simply through coding. The physical differences between the systems are probably the limiting factor.

That said, I do prefer 85A to 105A as far as weight goes. In sport mode it is pretty good, but in comfort it is still too light. I'd like to go further and drop it to say 60A, but there is no preset for that. There is of course that custom value field, but I'm pretty sure just putting "60" there will not do what I want. I'm thinking of trying "3C", which would be the hexadecimal equivalent of 60. I'll be sure to update here if I actually get around to trying this.

[cooolone2]

Niceeeeeee

[dradernh]

Originally Posted by SpencerC_6MT

P.S: eLSD Disabling
As a little sidenote for people who may want to kill the eLSD: the setting you're looking for is under the DSC menu, in one of the expert-mode submenus (I believe the one at the top of the list). The setting you're looking for is "C_Funktion_Differenzialsperre_aktiv_l" and simply toggle from enabled to disabled.

Terrific post – thanks!

I think it's worth noting that eLSD is only active in DSC OFF mode. I had it coded-out for track driving in DSC OFF when I had a Wavetrac LSD installed. Later, the dealer updated the car's software, and that coding was lost. I'm no longer going to the track and don't drive in DSC OFF on the street, so I've left eLSD enabled.

[SpencerC_6MT]

Originally Posted by Kernel Kurtz

There is of course that custom value field, but I'm pretty sure just putting "60" there will not do what I want. I'm thinking of trying "3C", which would be the hexadecimal equivalent of 60. I'll be sure to update here if I actually get around to trying this.

I'd love an update if you figure it out, but unfortunately I think it'll be more involved than that. Working off memory, I believe the values were:

50| 85A_with_tolerances
55| 85A
78| 105A
89| 120A

Those may not be exact, but you get the idea. The hex numbers aren't their corresponding current, so specific hex values may be required to use any desired current. I'm thinking our best chance would be to find out if any other model uses a max current lower than 85A, then plug in the corresponding hex value in case it's an option stored in the system but not shown by default.

[Dom147]

is there a m235iR steering code? or does anyone know what the m235iR uses?

[SpencerC_6MT]

Originally Posted by Dom147

is there a m235iR steering code? or does anyone know what the m235iR uses?

I don't have a option for it in my car, build date 2/2017. From my surface-level research, it seems the M235iR programming is custom for the car and wouldn't come with any production models, but I'd love if there were a way to change that.

[SpencerC_6MT]

Well, it looks like my car's EPS is the thing I'm going to obsess over for the next few days. Think it's about time to toggle some of these settings and see what I can make happen. If anyone has experience getting in the weeds with EPS coding, please let me know what you could find.

[Kernel Kurtz]

It definitely sucks that there is absolutely no documentation available for the vast majority of variables in eSys/Protool.

[Rotorav8r]

Can we get the Supra's power steering programming? That is based off the Z4 but the steering feel is way better.

[Kernel Kurtz]

Would be interesting to see the Supra's settings. I don't have one, and have no idea if it even uses the same modules or software as BMW.

[SpencerC_6MT]

Originally Posted by Rotorav8r

Can we get the Supra's power steering programming? That is based off the Z4 but the steering feel is way better.

Originally Posted by Kernel Kurtz

Would be interesting to see the Supra's settings. I don't have one, and have no idea if it even uses the same modules or software as BMW.

I'm 99% sure the F-chassis uses a different steering rack than the G-chassis, and even if it doesn't, it would take some jerry-rigging to download the new software on the old cars. Might be possible on a G42

I found the Alpina F30 settings to be pretty nice at 85A. Lighter than stock at low speed but heavier above ~15mph

[cooolone2]

So maybe the question is whether or not the Physical G Chassis Rack would "Fit" in place of the F series rack... A question I've brought up when those compared the M2 rack feel also. To no avail

Ultimately, if it bothered me that much, I might search a pick-n-pull for a rack and attempt a swap out. But it doesn't.

Good Luck