Just installed a 89650-53042 Steering ECU on my 2014 350C, which came with 89650-53100 (which I believe was the same part for all 5 years of C production, or close to it, not including the F-sport/sport packaged ones).

The change is absolutely amazing and very real. It did take about 4 drives (so far) to really feel the change. After installing it, I ran the EPS calibration, that went pretty much by the book.

The first drive, pulling out of my driveway and making a right, it felt a little be heavier, but not really that much of a change and the rest of the drive wasn't very noticeably different. I then took it on a 20 mile drive and it felt somewhat different, heavier. And also I noticed that I didn't have to "Correct" my steering so much. Before I found myself having to do minute left/right adjustments (probably due to tram lining) but now noticed that the steering was pretty much dead centered the whole drive and wasn't as "twitchy" but don't get me wrong, if you turned it, it still pointed in that direction very precisely.

Finally, drove it home another 20 miles and that's when the change was very obvious. There is so much more resistance to the steering wheel in general, but esp. when taking corners/curves. Before it felt like an on/off switch (the steering wheel), but now it feels heavier with graduated resistance, like I can actually feel the tire scrubbing off speed on turns as the weight builds up. Driving around an indoor parking lot, the wheel was heavier also, again feeling like it wasn't so detached from the front wheels.

I then put the car in sport mode and noticed 2 things 1) in the rain, I was able to floor it up an on-ramp w/o VSC kicking in, allowing just a little bit more wheel spin so I wouldn't lose my forward momentum. VERY NICE. I understand it affects the VDIM integration. Before, it would cut all power at the slightest slippage. 2) the steering weight was heavier overall, greater resistance and better feedback.

It doesn't make the steering any more precise (or less precise), but it does give you more communication as to which the direction the wheels are pointed in. Also, because of that weight building up.. if you took rapid left/right movements (like a slalom), the car felt more planted since the wheel was telling you what the car was doing. with the old ECU, doing that same movement was so overboosted, so you don't really know what the car is doing until it's PAST the point of doing it. With the new ECU, you can feel your way UP TO the change in direction, if that makes any sense.

Hopefully that helps someone. I have to say, it's probably my top 2 mod (the suspension being my most important one). Also, the car not only feels more planted and communicative, but it feels "heavier" and in turn, gives it a more solid/german/teutonic feeling to it. If you've ever driven a german car, you know why they call them "tanks" while even the best built Japanese cars (say the LS) could only really be called a "vault." This really helps give that impression that the car is more solid, now it's got more of a "tank" feeling to it, like it's carved from one solid block of steel!

 

Awesome write up. I have the 89650-53040, and I felt the same way coming from the stock AWD ecu. I think it was the softest steering wheel feel ever. With the ISF it does feel more planted. I would say even with the RR USRS bushings. The car felt about 15% more planted than before.

So if your looking for a better steering wheel feel. You can't go wrong with either ISF ecu's 89650-53041, or 89650-53042.

 

Very nice review of the beneficial subtleties that the later year IS-F steering ECUs provide (-41 and -42). This too is one of my favorite and most recommended mods to do on the ISX50 as it really adds a new layer of feedback, sensitivity, and confidence to the driver when driving on the street and especially on the track.

 

Great review. I love the steering ECU as well. Just being able to slide the car more without turning off traction control is a great benefit in the winter

 

Is this different from the one that comes on the X Package? I haven't felt a significant difference driving my friend's ISF compared to my 2008 IS350 X Package, although I didn't really compared the two specifically focusing on steering feel. I may have to change ECU if it is different. Great review.

 

Yes, the F's ECUs are a huge improvement over the x50's regardless of trim.

I've had the 41 unit for a while now, love it. Just a note for those that don't already know, turning on the Pwr button stiffens up the steering wheel a bit more with the F ECU.

 

 

Eddy, as I understand it, that is correct, you will not get the "even firmer" feel that the Sport button provides since you don't have that button. HOWEVER, you will get the "firmer" feel of the IS-F ecu, which I understand is even "firmer" and more calibrated over the Sport Steering ECU available on the F-Sport and Sport Packaged vehicles.

 

Yes, I really think this is the reason why the IS just never seemed to be able to compete with the 3 Series or even A4. Toyota did a major disservice in initially calibrating the steering feel and the suspension. When they finally released the F-Sport package, it was pretty much too late as BMW was already releasing their new 3 series and the IS was just too old to compete anymore. They should have had a sport package from the beginning. It would have also been great if they tweaked it over the years so by the time 11-13 rolled around, it was "perfect." I guess that's why the F-Sport package was available pretty early on the 3IS.

But they configured the IS to basically drive like an ES or GS, maybe they thought they couldn't beat BMWs so why even bother? But wow, with the F-Sport Suspension, Sway Bars and the ISF steering ECU, it's like the best of both worlds (Toyota reliability and close to BMW driving characteristics).

Another change to note was that before, in a parking lot, I could turn the wheel with just a pinky (that's how light the steering was) and now I definitely need to use at least a hand, LOL.

 

OPs write up is pretty much how the F-Sport computer feels. It is a Good feeling from 0 to 130 mph or just carving through the canyons at a good clip.
My only complaint is how quickly the VDIM kicks in and the nannies come into to play when pushing the car.

If you can find the 89650-53082 or 53081 F-Sport steering ECU you won't be disappointed.
There is no inch by inch input needed while cruising at any speed. It is firm, predictable, comfortable and if TRAC is off it's is firm enough to keep you out of trouble unless you completely cross it up.

I've driven a 250 and 350 non F-Sport and didn't care for them. I am very happy with this though. Well until you get serious about playing.

So if you track the car, get the IS-F ECU. For DD, the F-Sport will be a very nice upgrade and keep most everyone out of trouble should they cross it up.

 

I tried both the F-Sport and the ISF, I found the ISF ECU much better for these reasons:

1) Price-wise, it's not a huge difference in ECU cost (and the resale value of it is better anyway down the road).
2) Having heavier assistance under SPORT mode is a VERY nice change. So it's like getting 2 ECUs in one, vs. the F-Sport which only has one setting. Also, it did feel like the ISF ECU was a "sportier" calibration (heavier across the board, better weight build up and feel).
3) The better VDIM integration allowing for more "slipping" (Note, it will still NOT allow you to do something stupid, it's just not as initially intrusive) is surprisingly beneficial:

For instance, there's this one on ramp on a highway near me that has a little bump on it. When you're flooring it up the ramp to merge, every car I've owned with some kind of VSC will kill the power for 2 seconds when it hits that bump. That has always scared me and is dangerous, tbh. With this ISF ECU, it just lets the tires chirp a little, but doesn't cut power, so you don't lose forward momentum. In my other cars (and in the IS before I did the upgrade) I always had to plan when approaching that part of the onramp and so tended to lose acceleration time, otherwise, it cut power and feels like you stalled (this isn't a Lexus only problem, my BMWs, and other cars do it). The ISF ECU allows for this, while the F-Sport ECU still is intrusive.

4) If you're going from the standard ECU to ANY upgrade, I felt like going ISF had the most difference and best bang for the buck, the F-SPORT ECU might not be that much a of a difference to justify the trouble of doing this.
5) The '13-'14 ISF ECU is the last and most recent of the ECUs and probably had the best and final calibrations on it. Also, the -42 seems to have taken care of any notchy feeling or unusual vibrations that the -41 might have under certain circumstances.

I'd have to agree with Jeff Lange that the difference between the non-sport and F-Sport ECU is smaller, compared to the Sport and ISF ECU (which then means that if you're going from non-sport to ISF, the change is that much more noticeable): https://www.clublexus.com/forums/is-...l#post10143252

YMMV

 

Just want to chime in on my experience quickly. I have the first gen isf steering ecu in my is250. I felt the difference right away. Mine came out a ISF so i didnt even do the reprogramming and its been working flawlessly. Steering is way more accurate, stiffer and less boat like.

 

For the record, the steering ECU, each time it's calibrated, will feel "light" on the first drive and it seems pretty much the same on the second drive. By the 3rd and 4th drives (say after 10 miles or more) it firms up nicely. Just in case anyone installs a new one, but doesn't notice a change. You should also recalibrate any steering ECU when first installed.

I decided to recalibrate it last night to test it out and noticed it was very light during the first drive. Got heavier again after subsequent ones. Just like the first time around.

 

i have an 09 and can't turn the steering wheel with my pinky. stock ECU. running GSF lower control arm bushings, 3IS front shock assemblies, and have recently replaced my front sway bar bushings with OEM which noticeably stiffened up the steering. GSF LCAB alone help a lot with keeping the wheel on center.

 

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we're comparing apples to apples, so are on the same page. I happened to pick up my car used and did a complete suspension refresh by upgrading everything to f-sport components. Pretty much everything you described you did.

But the steering ECU is a completely different animal, I think you just had worn components which helped to tighten things up.

My 2014 didn't have much of a steering feel difference from those changes (but it did handle better), but the ECU change made everything significantly better.

If you can test drive one with an isf ECU, you'll see the difference.