This topic has been discussed already on this forum, so if anyone has detailed questions on installing an ISF Steering ECU on your 2nd Gen IS, there are many great threads on this. This post is basically my impressions after installation. Last year I started reading about members improving their steering response by swapping out their stock steering ECU with an ISF steering ecu. After searching for a used one, I found a guy selling one that came from a 2010 ISF with a little over 100K on it. One of the reasons I bought it was because I was having an issue with steering when going on long trips where the electric assist would seem to go dead for a second when making corrections. It wasn't anything dangerous, just very annoying. The dealer couldn't reproduce it or find anything wrong with the steering or the steering ecu, so I just chalked it up to an overzealous VSC. One of my hopes was the ISF steering ecu would not only make steering better, but eliminate that dead spot when going on long trips.

After receiving the ISF steering ecu, I became reluctant to install it. But after upgrading my Sway bars (F-Sport) and my stock LCA bushing to RR Racing Polyurethane bushings, a few members convinced me to do it, so this Tuesday I pulled out the tool box and did the install. It's not a difficult installation, the hardest part is getting the connectors off. After installing the ISF steering ecu, you can feel immediately that the steering response is much stiffer. I've thrown it into a few corners and it feels great, although in aggressive right turns the nannies seem to come on much sooner!

So far I really love the new steering feel, although I have not had a chance to do any freeway driving yet. I'm hoping that the dead steering when correcting at high speeds is gone. If that is the case, than it was definitely worth swapping it for the stock steering ecu

 

If the steering is more stiff, is it harder to turn? I think my car also have the odd steering feeling when going on the freeway in some curved parts.

 

No, it's actually not harder to turn. It feels more precise now. I've driven it on some curves and it's fine. I haven't had a chance yet to take it on the freeway, but in my experience slightly stiffer steering at high speeds gives you much better control. Previous to my IS I had a 2018 Civic Si which had much stiffer steering and it actually gives you better control. I'm hoping that this steering ecu fixes that odd steering you are describing. This weekend I will be taking it on the freeway to find out

 

how much did you buy it for?

 

$300 on eBay. I made an offer and it was accepted

 

Which nannies were kicking you around and have you tried ECT mode yet? That sounds suspiciously familiar to the 2013 F-Sport EPS ECU. It is all to happy to steer the car for you and/or apply diagonal braking to straighten the car out.

That said, and someone else will have to confirm this, but I'm pretty sure the EPS ECU swap has no impact on wheel spin when the lesser loaded wheel loses traction. Is that the nanny complaint?

By next week I should be able to chime in with 2013 F-Sport to 2011 IS-F EPS ECU swap and let you know my thoughts.

Edit: EPS ECU definitely impacts the wheel spin. The ISF ECU allows more wheel slip whatever the reason.

 

I was in normal mode (I haven't tried ECT mode yet) and I hit about quarter or more throttle hitting a right turn and the VSC light started to flash, power was pulled a bit and there was a little bit of strategic braking, I have the E-LSD so it was probably trying to emulate locking diff as well

 

Switch to ECT Power and you'll have access to VDIM Sport Mode (it will also firm up the steering even further).

 

Is this automatic when you go to ECT power or do you have to access this setting to turn it on?

 

It's automatic.

 

Finally got to drive it on the freeway, and steering is night and day from the stock steering ECU. Holds a straight line better, and the firmer steering gives a feeling of more control. When I had a 2018 Civic Si, a lot of people from the Honda community would buy a device called a Ktuner and load a tune from a company called Two Step performance (TSP stage 1) which would increase the throttle response and WHP by 55 horses. Everyone would say "this is how Honda should have tuned it from the factory". Well, this is how Lexus should have tuned the Steering ECU'S on IS250/350's from the factory!

 

Oh wow that is great to hear. I have the same issue with a dead spot from time to time and the wheel fighting to correct.
This has been on the radar for a while now to upgrade but I wasn't sure it would fix the other problem.
Thanks!

 

It's definitely one of the better mods. To know 100 percent if it eliminates the "dead spot" in the steering I would need to find out on my next trip to Socal. That's usually when it starts happening more consistently, I'm doing about 80 mph for long stretches on different road conditions. Yesterday I tried my best to see if I could make it happen, steering stayed perfectly smooth.

You should do it. There are some on sale right now under $500 new, but you will need to get them calibrated from a Toyota or Lexus dealership



I also saw a used on for sale on Ebay for $350, it looks really clean. It's from a pre-2011 ISF (2008 ISF)
https://www.ebay.com/itm/LEXUS-IS-F-...EAAOSwJHhen1jI

You won't have to get this calibrated, it would be straight plug and play

 

I tossed in the IS-F EPS ECU. Took about 20 min. The connector is charmer, pop the black lock up, squeeze the connector from the backside pulling it it up to release what seems like a secondary catch and walla, the connector de-latches pushing it self away. All you need is a large pick tool. Do the one on the right first (power cable). Then the simple squeeze one, then the forward most connector on the side with two.

The hardest part was getting those stupid battery cable tie downs free on the outside of the battery, But after being mean to them, they got TF over it! lol And still latch!

I only did a short drive and can say that low speeds require more input at the wheel (higher resistance), but otherwise feels the same through the corners and straights. It will after 45,000 miles take some getting used to as it is not the way it was whereby muscle memory drives the vehicle effortlessly.
'll get it on the freeway tomorrow and maybe this weekend the canyons where VDIM can show its true colors. One observation is this EPS unit does allow more wheel slip than the F-Sport unit should it be pushed through the corners and body lean lifts a tire. The same can be said for the launch.

Out 89650-53082 F-Sport EPS ECU 2013
In 89650-53041 IS-F EPS ECU 2011

 

A quick pic of the moisture proof locking connectors.
That little black tab pops up to about 4mm. Do not rip it out completely. To open and release, lift up in the center from the wire side. Doing this will activate a cam the pushes two of the connectors about 45% free of completely decoupled.


That's about it. Seat it, push it down to secure it push the little black tab back in.