Special Projects - Electro Power Steer

[frankenwabbit]

If you use the Subaru pump, you have to use the Subaru Cybrid power steering fluid. Kiwi... did/do you have any plans to incorporate the steering sensor from the mr2 power steering ecu to vary the steering assist, or are you running the pump always on? Just curious. Ian

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[firebert]

excellent write up. I'm thinking about foing this in the future as well.

However I find it odd that you said it was a bit loud since the pump is a OEM toyota part.

And is it nexcessary to have a machine shop fab the pump bracket? A home made bracket wouldn't be heavy-duty enough?

[Justin Jones]

Originally Posted by KIWI

Are you going to bid on it ? If not, I might just to check it out.

By all means, bid! I am not in any position right now to start more projects on my civic, I have enough stuff going on with that thing right now... like getting it running.

[rotten]

Originally Posted by KIWI

Now if the Subaru type works and I believe there is a Mazda electric power steer pump available as well, then it might be a worthwhile proposition.

PRetty sure it is the Mazdaspeed 3 that has the EPS pumps, but they are pretty pricey from Mazda.

[KIWI]

Originally Posted by firebert

excellent write up. I'm thinking about doing this in the future as well.
However I find it odd that you said it was a bit loud since the pump is a OEM toyota part.
And is it nexcessary to have a machine shop fab the pump bracket? A home made bracket wouldn't be heavy-duty enough?

It's probably very noisy because we did not rubber mount it. And it is a race car so I did'nt care.
You can easily cut out a bracket, or brackets to mount the pump. We just happen to have easy access to a water jet, so were kinda lucky.

Originally Posted by frankenwabbit

If you use the Subaru pump, you have to use the Subaru Cybrid power steering fluid.
Kiwi... did/do you have any plans to incorporate the steering sensor from the mr2 power steering ecu to vary the steering assist, or are you running the pump always on? Just curious.
Ian

Now there's a problem if you want to make it one....
Honda fluid for the Rack and Subaru Fluid for the Pump???? Decisions ...decisions... Hell it's a Honda race car, so Honda Fluid it is! If it Craps out I'll let you know.

I have no intention of incorporating the steering sensor from the MRII power steering ecu to vary the steering assist... Way beyond my electronics capabilities!
However, It is probably a fairly simple step further to do so... All the wiring comes with the pump, so with a little research at Toyota you could probably do it.
In our situation, were quite happy to switch it on and off when we need it. It's also very handy when you are pushing the race car around the shop without the Engine running!

Originally Posted by rotten

I've heard that the Subaru pump draws more current than the MR2 pump.

Possibly it does? But as long as it's less than the HP the stock engine driven unit uses... who cares?
And as far as Rallying is concerned, are you talking about parasetic loss because the alternator is drawing more power because of the Lights etc?
I'm using this in a Road Racing situation, so all the alternater has to do is keep the battery charged... oh yes and now power the Steering pump.
And frankly the saving in HP is less important to me than the comefort of the power steering.

Kiwi

[firebert]

Originally Posted by KIWI

I have no intention of incorporating the steering sensor from the MRII power steering ecu to vary the steering assist... Way beyond my electronics capabilities!
However, It is probably a fairly simple step further to do so... All the wiring comes with the pump, so with a little research at Toyota you could probably do it.

I did a bit more research after reading this thread. I'm not sure if my source are correct but it says these extra leads controls the drive speed of the pump in relations to either vehicle speed or steering angle (or both- different sites has different info) and is controlled by way of a PWM with signals coming in from the VSS and/or steering rack.

So in that case the pump is driving at a lower RPM while the vehicle is in motion which probably would extend the life of the motor and brushes. - Now my question is; With the leads disconnected, is the pump being driven at maxium RPM or minimum? And if it is being driven at maximum RPM would that mean the motor/pump wouldn't be very reliable in the long run.

I know this might not matter if it was ment for a full on track car but i'm thinking of incorperating it into a daily driver I'll do some more research - seems engineering students are incorperating these electro-hydralic pumps into their converted EVs.. argh I can't stand how boring engineering projects are getting.

[KIWI]

Originally Posted by firebert

I did a bit more research after reading this thread. I'm not sure if my source are correct but it says these extra leads controls the drive speed of the pump in relations to either vehicle speed or steering angle (or both- different sites has different info) and is controlled by way of a PWM with signals coming in from the VSS and/or steering rack.

So in that case the pump is driving at a lower RPM while the vehicle is in motion which probably would extend the life of the motor and brushes. - Now my question is; With the leads disconnected, is the pump being driven at maxium RPM or minimum? And if it is being driven at maximum RPM would that mean the motor/pump wouldn't be very reliable in the long run.

I know this might not matter if it was ment for a full on track car but i'm thinking of incorperating it into a daily driver I'll do some more research - seems engineering students are incorperating these electro-hydralic pumps into their converted EVs.. argh I can't stand how boring engineering projects are getting.

Hm-mm, You raise an interesting point, I hadn't really thought about it. I imagine without the speed control wires being hooked up, the pump will be running at Maximum speed all the time... it sure sounds like it!
For my purposes it doesn't really matter, if the pump burns its self out after a couple of seasons, it's cheap to replace. However I would be interested in finding out a little more about the speed control as long as it didn't mean carrying a whole heap more wiring and widgets!

Kiwi


Modified by KIWI at 8:07 AM 2/19/2008

[frankenwabbit]

Originally Posted by KIWI

Hm-mm, You raise an interesting point, I hadn't really thought about it. I imagine without the speed control wires being hooked up, the pump will be running at Maximum speed all the time... it sure sounds like it!
For my purposes it doesn't really matter, if the pump burns its self out after a couple of seasons, it's cheap to replace. However I would be interested in finding out a little more about the speed control as long as it didn't mean carrying a whole heap more wiring and widgets!

Kiwi


Modified by KIWI at 8:07 AM 2/19/2008

well...you'd have the the power steering ecu boxes, and the wires that run up the steering column that reaches up to the steering sensor.

Since I'm still green when it comes to electronics, I'm trying to figure out how to graft the speed sensor stuff.

http://www.evalbum.com/tech/mr2_powersteering.html

I've looked at that link for help/clues.


Ian

[KIWI]

Originally Posted by frankenwabbit

http://www.evalbum.com/tech/mr2_powersteering.html

I've looked at that link for help/clues.
Ian

Wow! It's all there huh.... Can you follow it???

Kiwi

[rotten]

Originally Posted by KIWI

Possibly it does? But as long as it's less than the HP the stock engine driven unit uses... who cares?
And as far as Rallying is concerned, are you talking about parasetic loss because the alternator is drawing more power because of the Lights etc?
I'm using this in a Road Racing situation, so all the alternater has to do is keep the battery charged... oh yes and now power the Steering pump.
And frankly the saving in HP is less important to me than the comefort of the power steering.

That's the thing, is the guys that tested it found that the electric pump took more parasitic loss than a oem belt-driven hydraulic pump. I'll try to find the specifics of the test.

I seem to recall that both the Subaru and the Toyota pumps draw something crazy like 50A at peak, which on our cars means ALL THE POWER THE ALTERNATOR MAKES. So if you have other stuff like lights, heater, you're going to be pushing it.


Yeah there is no doubt that the power steering is more effective for two reasons
1) Its just faster--back in like the 1970's, the WRC teams did testing and discovered that PS is something like 1.5 second per mile quicker than manual (in a rally situation, which is quite a bit more 'busy' on the steering than RR, but still).

2) Fatigue-- Even if you're in great shape, fatigue can be a big factor, and it will make you make more mistakes and be slower.

[firebert]

Originally Posted by frankenwabbit

well...you'd have the the power steering ecu boxes, and the wires that run up the steering column that reaches up to the steering sensor.

Since I'm still green when it comes to electronics, I'm trying to figure out how to graft the speed sensor stuff.

http://www.evalbum.com/tech/mr2_powersteering.html

I've looked at that link for help/clues.


Ian

good stuff. i'll see if i can work it out when I have some extra time. I had some circuit analysis courses under my belt but electronics seriously 0wns me sometimes. Hopefully it's simple enough.

[frankenwabbit]

Originally Posted by KIWI

Wow! It's all there huh.... Can you follow it???

Kiwi

I've tried.


...traced the wiring from the PS ecu but that's about it. Still scratching my head on the grafting of the VSS sensor and the steering sensor.




Took me a while to pull out the PS particulars from a mr2. Anywho, I'll try to take some closer pics of the labeled wires and post them up.

btw...thanks KIWI for posting up the stuff for the fittings to the pump...one less thing to figure out!

[98SpecR]

Originally Posted by rotten

I seem to recall that both the Subaru and the Toyota pumps draw something crazy like 50A at peak, which on our cars means ALL THE POWER THE ALTERNATOR MAKES. So if you have other stuff like lights, heater, you're going to be pushing it.

I'm not sure what the output is for B-series alternators. However, K-series alternators' outputs are as follows:

Mitsubishi = 90A
Denso = 95A

Both alternators operate on 13.5v at normal engine temperature.

[rotten]

Oooh... THat is pretty good! I wonder if the K-series ones could be retro fitted to the B-Series unit. 90-95A is a fairly high output unit.

When I was working on the lights for the Integra rally car, I recall the amp being able to put out 60A.

HO alternators are out there, can get 130 amp units for a couple hundred bucks. I decided to go with HID aux lamps instead, which drastically cut the draw--and so never had to go that route. But with an electric power steering pump, it becomes an issue again.

I think though that even at 50A, with a good battery, you'd be more than fine in an road race situation.

[Andrew Marquis]

Great information Kiwi!

Best of luck on future RR races for you!

[ATS*EG2]

[Super79Dave]

So after reading this thread i got to looking under the dash of an 07/08 toyota yaris which uses electro p/s and it is al mounter in the column.
The column itself is approx 750 to 800 from the dealer.
You'd have to fab a custom steering column intermediate shaft mounting brackets etc... however i'm not sure you'd be able to run the stock dash.
The micro switches and everything are all housed in the column, and just attaches to a normal manual rack.
Someday i'll take a picture of the assembly.
Anyway just a another theory

[rotten]

Do you know if it is made by Nippon Denso or Delphi? Or is it a Toyota setup?

I know that the GM EPS units (not hydraulic) like the one I have at the shop from a new Chevy Malibu use the CAN bus to talk to the ECU in order to get things like vehicle speed sensor, and I'm pretty sure any new car would have a similar setup.

I would love to have an EPS unit, but I haven't been able to reverse engineer either a converter for the speed sensor or a emulator setup with a potentiometer to adjust the amount of 'assistance' the motor gives.

There is a EPS unit from a car in Europe (have to dig up the details) that some folks have reverse engineered the signal and have built a controller box, but it ends up taking like 60A+ anyway and is a fairly early EPS unit.

It would be sweet if a Yaris setup could be used standalone.

[spooledhonda]

i'd like to say good work and i'm going to make somthign like this soon. awesome work

[ED9man]

I know that some Hondas have the power steering tied into the VSS. How does this affect the amount of assist at different speeds? I'm just wondering if having the pump running full speed all the time would have to steering feeling overboosted at higher speeds where less assist is needed?

[ED9man]

70A for a B16a

When is the pump actually going to be drawing maximum amperage? Only when you are sawing the wheel really hard? I'm worried about the reserve capacity of a small battery like the Odyssey I have but I'm hesitant to drop a lot of money on a high amperage unit. I'm assuming that kiwi hasn't had any battery issues?

[Karcepts]

Originally Posted by ED9man

I know that some Hondas have the power steering tied into the VSS. How does this affect the amount of assist at different speeds? I'm just wondering if having the pump running full speed all the time would have to steering feeling overboosted at higher speeds where less assist is needed?

It does seem beneficial to have the pump operate dependent on vehicle speed; at the same time, look at what our factory belt driven pump goes through. The pump may be at high rpm at high vehicle speed or may be at low rpm at that same high vehicle speed (depending on what gear you are in). Has anyone ever really complained or felt a difference under these different circumstances on a factory belt driven pump? Just throwing this out there… Actually, when power steering is needed the most (at really low speeds), most of the time, the standard belt driven P/S pump is running at a relatively low rpm compared to the other situations. At the same time, I haven’t done the research to look into the mechanics involved with a factory Honda pump compared to the pump found on this MR2 unit. Maybe the Honda pump operates differently such that you don’t notice any over-assist? You really wouldn’t expect them to be much different though…

I just wanted to say that this is a great write-up Kiwi! I plan on performing this switch shortly to try out!

If anyone is interested, I am having a few brackets made up for mounting the MR2 pump with EGK1 or EKK2 mounts (only known fitment at this time). I will have 10 in less than 2 weeks. 5 are already spoken for, but the rest are up for grabs if anyone wants them. PM me if interested.












Modified by Karcepts at 9:53 AM 3/6/2008

[ED9man]

The Helms for the Integra had a good explanation of how the system works. The pump is designed to push fluid at a constant pressure and the mechanism that regulates the boost is built into the rack and it uses the speed sensor on the transmission to regulate the amount of assist. So even with the Toyota pump, which does operate at a similar pressure, the amount of steering assist should feel like a factory car where most of the assist is at low speed and less at high speeds when using the stock rack.
The other thing I am curious about is how much power the alternator can pull running at max amperage to see how much more efficient running an electric pump really is. There is of course still the advantage, as far as I have read, of the inability to "beat" the pump like you find with a stock belt driven pump, which is what I want to avoid with the set up I am planning to use, where I am going to use a quickener which will make this pump beating condition more likely to happen. As well as the fact that it's one less thing running off the crank and can be mounted wherever.

[kommon_sense]

Originally Posted by ED9man

The Helms for the Integra had a good explanation of how the system works. The pump is designed to push fluid at a constant pressure and the mechanism that regulates the boost is built into the rack and it uses the speed sensor on the transmission to regulate the amount of assist.

I think you may be mistaken there. I imagine the rack does have some mechanism for bleeding off excess pressure. However it is not tied to the speed sensor at all. There are no electrical connections to either the pump or the rack. They are 100% mechanical/hydraulic.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote"> So even with the Toyota pump, which does operate at a similar pressure, the amount of steering assist should feel like a factory car where most of the assist is at low speed and less at high speeds when using the stock rack.
The other thing I am curious about is how much power the alternator can pull running at max amperage to see how much more efficient running an electric pump really is.</TD></TR></TABLE>

I think that it may really depend on the alternator. K-series alternators are 90-95A, while b/d-series are much lower and may create more load for them.

[ED9man]

There are hydraulic lines running into the speed sensor that sits on the diff from the rack that control the pressure based on speed.