Toyota Prius EPS Swap
Toyota Prius EPS swap
This is a write up for people who have swapped, or want to swap, their EPS(Electronic Power Steering motor) for a TSS-P(Toyota Safety Sense) Prius. This will include a link to Erich's video, some advice, and my recommended settings for people who do this.
A Reason
The reason behind this EPS swap is to give the car a more stable lateral experience and a higher torque for better turns. This is the new method recommended over ZSS(Zoro Steering Sensor). After the EPS swap you'll experience less/no more ping ponging, and it should take more turns than before, speed pending.
Parts
- 2021/2022 Toyota Prius EPS (Part Number 89650-47600 or 89650-47800)
- A socket set, a 10mm, 12mm, and 14mm
- A 3D printed 100% in-fill PETG Cogwheel - Download from the official discord
- A bungee cord
Erich's Video
Things to keep in mind by Discord contributors
- Make sure you discharge your airbags before you start by disconnecting your 12v battery and waiting approximately 5 minutes before continuing.
- Your air ducts are fragile, during my install, we broke mine and used tape to 'fix' it.
- Breaking loose the bolts that secure the steering to the frame. You will need a breaker bar if you aren't strong enough or try a similar sized standard socket (9/16?).
- Getting the solid cogwheel to fit on the EPS. I ended up placing the cogwheel halfway in the EPS and the other part of the steering until they barely fit in one another. Then I wrenched it down with the two bolts that secure the EPS to the steering.
- Before closing it all back up, double check that the EPS wasn't installed backwards.
idnot's recommended settings
I recommend disabling lateral settings in FrogPilot. You can do this by going to Settings -> Controls -> Lateral and just toggle lateral off. The reason for this is, currently, we don't have an NNFF(Neural Network Feedforward) profile, and if you do have NNFF enabled, it'll load the default 2017 Prius NNFF profile, which is wrong, as we now have to use the 2021 Prius NNFF profile. I have put a PR in for us to get an NNFF profile, and it's waiting for approval.
I'd recommend using the WD-40 driving model as it has decent lateral and longitudinal control. Keep in mind, this mod will give you more torque yes, but it won't:
- Override the software limits that Comma sets
- Make steering super smooth
- Provide a perfect lateral experience
I've noticed that for me, I get more torque, but limits set by Comma and Toyota will still affect you. There is, in the lateral settings, steering ratio setting, which will allow you to modify how twitchy your steering is. I don't touch it, but if you do, please do it in small amounts and make sure you have a set route to test.
This modification isn't the perfect solution, but it's quite good and recommended if you have the money, skills, and time to do it. The biggest things to look out for were outlined in the sections above. If you have any questions I'd recommend you talk to Erich in the official Comma discord, myself(@idnot) or @mruno in the FrogPilot discord.