Miata electronic power steering


#1

My 2013 MX-5 Miata came with “electronic power steering” according to the Monroney sticker. I thought it meant electric power steering since there is surely some electronic circuitry involved in electric power steering. What I got certainly is not electric power steering because there is an engine-powered hydraulic pump and a reservoir labeled “power steering fluid”. What did I buy? How does this system work?


#2

You may have something called electro-hydraulic power steering. It uses an electric motor to turn the power steering pump and provides hydraulic pressure to a conventional power steering system. Hydraulic power doesn’t have the artificial feel of electric motor assist and the pump doesn’t draw power from the engine when you go straight.


#3

No, it has an engine-powered hydraulic pump. Engine, as in internal combustion engine. The engine spins the pump via a belt. In that respect, it appears similar to the system on the '58 Chevy I used to have.


#4

As far as I know, the Miata has a traditional hydraulic steering system. The only “electonics” in it is a pressure sensor switch in the power steering pump that tells the ECU to raise the idle when the steering wheel is turned at idle.


#5

Post a picture of the sticker. Either it’s a mis-print or you read it wrong.


#6

I did a little research and it turns out that Mazda does advertise an “electronic hydraulic power steering system”. I was unable to find out how it works. It may be part of their stability control system.


#7

Here’s a good look at the electric power steering on the new Mazda 3. But it’s totally different from what the OP describes on his Miata, which sounds like conventional hydraulic. I haven’t found anything to suggest that a 2013 Miata has electric power steering.


#8

It’s different. And from what I was able to find out, what the OP wrote is true and accurate. I just can’t find any technical information about it to find out how it works.


#9

This might solve the mystery:

“There are two kinds of “electric over hydraulic.” On type uses a constant-flow belt-driven pump. Full flow is used in parking situations, and at higher speeds a bypass valve siphons off a portion of the flow so less assist is generated (and more feel) at higher speeds. This would more accurately be described as electronically controlled power steering, or ECPS. Because it has a belt-driven pump, many don’t consider it true electric. But Hyundai and Kia did promote it as such about 10 years ago.”

So the Miata probably has the traditional belt-driven hydraulic system with an electronically controlled bypass valve that controls the amount of assist.


#10

Jesmed1’s theory is probably very close, but I would like to hear from someone who is familiar with the system. The GM cars I have had in the last 40 years have had a feature like that described by jesmed1. A simple pressure switch on the high pressure hose raised the idle speed. On carberated cars, it was just a solenoid that bumped up the idle stop on the throttle. On fuel injected cars, it triggers the idle control valve to open (probably through the E.C.M). I don’t see how anybody could consider power steering that gets it’s power from an engine-driven pump as electric. It even seems disingenuous for Mazda to label such a system “electronic”. Since the Mazda2 had had true electric power steering http://ir.trw.com/releasedetail.cfm?ReleaseID=285979, for several years before this car was made, I figured this one did too, when I saw the Monroney sticker. I would like to post a picture of it for shadowfax if someone can show me how. I tried to post a picture in another forum a few years ago. I spent hours researching methods and following instructions. All it did was post a link to my Flickr page so everybody on the forum could see all of the pictures there. Not what I wanted. I just want to post a picture here in this forum. But, the Monroney sticker that was on my car says exactly, under “Standard Equipment”, “electronic power assisted rack and pinion steering”.
On a related topic, the steering does not lock on Miatas after the 2009 year model. This was another unpleasant surprise after I bought the car. Apparently, many new cars don’t have a steering wheel lock and not many buyers know about this. My salesperson didn’t tell me. I have asked the NHTSA for a list about a month ago,but they have not responded.


#11

Get your photo into your computer as a .jpg file of ~500k and then click on “Attach a file” and choose your picture.


#12

I guess I read ‘electronic’ as ‘controlled by electric circuitry’, and ‘electric’ as ‘powered by electricity’, so I don’t have a real problem with Mazda’s wording, assuming there’s some electronic control involved.


#13

Insightful, how do I control the file size? In the camera, or in the computer?


#14

If it were me, I’d be happy with your Miata’s (basically) hydraulic power steering. Straight electric power steering is still glitchy and can have a strange feel.

Electric power steering is gaining popularity with automakers because it’s slightly more fuel efficient, not because it gives better road feel, which it doesn’t.

The article below is from 2010 but much of it is still true today:


#15

I do it in my PC using a program called “Paint.” I open the picture in “Paint” then use “Image” and “Stretch/Skew” to shrink it from 100% to whatever I want. Some have attached up to 2Meg pictures here and it works OK.


#16

On Linux, I use a command at the command prompt to change photo size. Very fast.


#17

Insightful, is that 500k bytes or pixels. When I resize it in Paint, it tells me the horizontal and vertical pixel count and I can multiply those together and get the total pixel count, but I don’t see a way to get the file size in bytes. It does tell me the original file size at the bottom, but that doesn’t change when I shrink the picture.


#18

Steering wheel locks are a thing of the past. There is no reason for them now. They were originally designed to lock the steering wheel (and gear shift on column shifted cars) so a thief couldn’t drive your car after “hot wiring” the ignition to start it. With all the anti-theft and security measures on cars nowadays there is no need for a locking wheel.


#19

Right, there’s a bit of trial and error to get the hang of it. Shrink the pic, then “File”, “Save As…” with a new File name, then check the new file for size. Really anything from 100k to 2M (bytes) is fine.


#20

Ok, here is the picture of the Monroney sticker. That was almost easy (thanks, insightful). I am fairly satisfied with the steering. It has some friction in the center and the car tends to wander a little because minor corrections are not as easy as they could be. I hope it is just because it is nearly new and the piston is still a tight fit in the barrel (not sure of the exact part names). If the car had been available with manual steering, I would have gotten that. I have had 3 cars with manual rack and pinion steering and I prefer it in a light car: 1973 Porsche 914 (excellent, as expected), 1986 RX7 Sport (almost too heavy for it, but great feel and good upper body toner), 1994 Civic CX (surprisingly excellent). Electric steering has the potential for assisting steering effort without affecting feel. I knew Mazda made cars with electric steering. I knew Miatas had a reputation for excellent steering. I saw the Monroney sticker and jumped to the conclusion (more of a hop, I think) that Mazda had done the work, solved the problems, honed and perfected electric steering and I was glad to reward their efforts with my hard-earned money. I am not so glad now.