Eps

[scottg]

I have a problem with my electric power steering as I have a very loud grinding sound coming from inside the rack.
Can anyone confirm if there is a problem putting an EPS rack in a 1991 car that has come from a 1999 or 2002 car?

[Kaz-kzukNA1]

You need to consider the combination of the EPS rack and the controller.

If we ignore the RHD/LHD differences, there are mainly two different EPS racks and three kind of EPS controllers available for the EPS system.

From 97 onwards, the rotational sensor was eliminated from the rack so there is only one connector at the rack.
You can’t use this on any controllers requiring the rotational sensor input.
It will trigger the EPS warning light and will disable the EPS.

I don’t like using the word ‘year model’ as the definition is different between the countries and rather use the VIN but for your reference, if you are going to keep the EPS controller from 91 – 96 models on your NSX, you must use the EPS rack with two connectors.
This means, you need the rack from the 91 – 96 models.

If you have the later spec EPS controller (97 onwards), you can use both type of racks. If your EPS rack is from the early two connector type, you just don't connect one of the connector (rotational sensor) to the controller.

From the test driving result, there is noticeable difference in EPS feedback and the power assist changes over the speed range depending on the rack/controller combination.

Obviously, the most tuned one is the latest rack with the latest controller.


So, if you have access to the 99 or 02 EPS rack, ideally, you should consider upgrading your EPS controller to 97 or later one though both the EPS rack and the controller are mega expensive.

If you are going to upgrade the EPS controller and if you have modifications inside your transmission, be careful as it may trigger EPS warning light at high speed.

Kaz

[scottg]

So if I buy the rack and controller from a 99 car then will the existing loom be ok Kaz a d will this be the solution?


You need to consider the combination of the EPS rack and the controller.

If we ignore the RHD/LHD differences, there are mainly two different EPS racks and three kind of EPS controllers available for the EPS system.

From 97 onwards, the rotational sensor was eliminated from the rack so there is only one connector at the rack.
You can’t use this on any controllers requiring the rotational sensor input.
It will trigger the EPS warning light and will disable the EPS.

I don’t like using the word ‘year model’ as the definition is different between the countries and rather use the VIN but for your reference, if you are going to keep the EPS controller from 91 – 96 models on your NSX, you must use the EPS rack with two connectors.
This means, you need the rack from the 91 – 96 models.

If you have the later spec EPS controller (97 onwards), you can use both type of racks. If your EPS rack is from the early two connector type, you just don't connect one of the connector (rotational sensor) to the controller.

From the test driving result, there is noticeable difference in EPS feedback and the power assist changes over the speed range depending on the rack/controller combination.

Obviously, the most tuned one is the latest rack with the latest controller.


So, if you have access to the 99 or 02 EPS rack, ideally, you should consider upgrading your EPS controller to 97 or later one though both the EPS rack and the controller are mega expensive.

If you are going to upgrade the EPS controller and if you have modifications inside your transmission, be careful as it may trigger EPS warning light at high speed.

Kaz

[Kaz-kzukNA1]

From your OP and also the signature section, you own either the 91 or 93 model.

This means that your EPS is the original version which has two separated boxes.
One box as the brain (controller) located behind the glove box and the other one as the power source (power box, lots of FET and relays) located at the passenger foot well.
From 95 model onwards, these two boxes were integrated into one box and located at the passenger foot well area only.

So, if you are sourcing the controller from the single box era, I’m afraid you must get the chassis loom as well.

And removing the loom related to EPS from existing car is not an easy task.

The loom is combined with rest of the chassis loom with protective tube and lots and lots of electrical tape so it’s possible but mega time consuming with lots of patience required.

In Japan, some of the breaker yards will simply cut the cable in half in order to save the time removing the EPS loom and let the buyer to deal with the rest.
It is almost impossible to just hop into the breaker yard and remove the loom by yourself.


If you have access to the donor car, just take your time.


As a side note, if the controller parts no is -023 as the last 3 digits, make sure to replace the internal relays with the higher current capacity one.
Otherwise, 100% guaranteed to trigger EPS warning light at some point in the future.
It could be next day or 12+ months later depending on how you use your EPS.
Ver.023 controller was fitted to NSX with EPS on around 95-96 models.


As in your other post in 'Wanted' forum, you can have your EPS rack overhauled in US and also in Japan as the last resort.
This is what is involved in EPS rack OH.

http://tyiz.jp/NSX/PowerSteering/GearboxOH.html

Thank you to Mr Toyoizumi at KSP Engineering, Japan for sharing this info.
It’s in Japanese but the photo will provide you with some idea.
KSP has been offering this OH service for many years with lots of know-how and because of this bench system that they created, lots of Honda garages are now sending the customer’s EPS rack to them for the OH due to strict MOT in Japan.


In the mean time, if you find used manual rack or even the new one (not that expensive in Japan, RHD still available but I heard LHD manual rack is no longer available???), you can run it in place of your EPS rack while waiting for the overhaul.

Needs to change the universal joint to manual one but that’s easy.
And no need to say the requirement for the alignment service.

Kaz