Increase efficiency by disabling electric assist in steering

20521 Views 82 Replies 31 Participants Last post by IamIan, Jun 21, 2010

Guillermo

Discussion Starter · Jul 13, 2004

This is for the traditionalists and the hard-core milleage freaks.
By removing the fuse of the electric assist power steering you will conserve battery power that would otherwise be used every time you turn the wheel. It also gives you better feel of what is going on between the road and the tires at higher speeds.

This is a very simple, quick and easy mod you can do in 20 seconds just before you drive to work tomorrow to feel it for yourself.

Open the hood.
Look for 40A power steering fuse as shown on fuse box decal.
Remove the 40A power steering fuse and store in your cup holder.
Drive the car and feel the real effort it takes to drive without power steering. :shock:

It's not that bad really, it feels firm during normal driving.
I first tried it an auto-x and it felt like I was wrestling a bear when turning fast at low speeds. But at higher speeds I had a better feel what the tires where doing. On the highway I drove home and it feel firm but nice.
I'll try it on and off a few times and decide what I prefer after a few days.

Tell me what you think after you try it.

61 - 80 of 83 Posts

ikhoudvanu199

· #61 · Mar 26, 2008

i had to make a quick stop today while I was about to shift, so only had one hand on the wheel...it got a little squirrelly to say the least...i honestly felt if i had to do any kind of steering i would not have been able to

im putting the fuse back in....the slight improvement in mpg is not worth an accident

joecvt

· #62 · Mar 26, 2008

Does the power steering unit really use that much power to actually see a difference in MPG?...I would assume when you are mostly going straight the motor would not be in use most of the time and it would be just the power to the controller....Also, this is speed sensitive steering so when you are going at highway speeds, I don't think there is much if any steering assist (according to the service manual, the controller is able to vary the voltage to the motor) so even if you are turning slightly at highway speeds, I don't think much power would be used. Wouldn't you get the nearly the same efficiency by turning the radio off or having the fans on low if possible?

Perhaps some people like the feel of the EPS being off but I tend to agree with ikhoudvanu199 about the concern of a quick evasive maneuver.

JoeCVT = Just your average CVT owner

dtlee

· #63 · Mar 27, 2008

I think the fact that there is information on this very website instructing us to pull the fuse for the EPS in order to do a manual calibration attests to the fact that the EPS draws a lot of charging current, at least enough to make a difference when doing an SOC recal, right?

I drive without EPS and although it is a bear at times, I like the feeling. I could see how women would have trouble with this modification if there is a lot of parallel parking to be done, but otherwise I feel like it increases road feel and car control. If you've never driven a car with no power steering, a huge hint is that moving the car helps A LOT with steering resistance. Even crawling the car will decrease steering resistance.

My first car didn't have power steering so I learned this the hard way. Oh, wait, no.. my dad actually smacked me on the back of the head for putting too much stress on the steering components by trying to turn while stopped. I love my dad. =)

IamIan

· #64 · Mar 27, 2008

I am not as old as many here ... but ... I started out driving on a 1977 Ford Van... no power steering at all... No fuel injection with a manual choke... Highbeams was a pedal on the floor... etc...

I have not yet put a meter on the motor to log how much it uses... but I will say this....

If you are used to and proficient driving without power steering any electricity it uses is just a waste of energy.

I have estimated between 0.04367449 and 0.016377934 gallons of gas will be offset for each 1 Ah from the 144V NiMH battery that did not come from gasoline use.

Every 1 Ah of energy conservation is the same as or better than 1 Ah of energy that did not have to come from Gasoline.

How much that reduction in gasoline effects your FE and MPG depends on the FE & MPG you get on average, and over what amount of time.

For instance at ~150 Hours per Year at an average of ~100mA of current for each hour driven would yield ~15Ah saved or about ~0.65511735 to ~0.24566901 Gallons of Gasoline not used per year... at an average of 60 miles per gallon that is up to about ~39.3 additional Miles per year on the same number of gallons.

At ~1Amp of average current use per hour you have ~150Ah or between ~6.5511735 to ~2.4566901 Gallons not used per year.... at an average of 60 MPG that is up to about ~393 additional miles per year on the same number of gallons.

If you don't like it don't do it.... if you are comfortable driving without power steering than maybe look into it....

I would think an alternative to pulling the fuse would be to put a switch on the 12V power leads going to the electric power steering motor.... although that might cause a code.

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joecvt

· #65 · Mar 27, 2008

dtlee said:
I think the fact that there is information on this very website instructing us to pull the fuse for the EPS in order to do a manual calibration attests to the fact that the EPS draws a lot of charging current, at least enough to make a difference when doing an SOC recal, right?

I don't think that you can conclude that the motor must draw so much power that it would affect a recal accuracy. If you follow that thought further, That is supposed to be the correct procedure when performing a manual calibration. But with that procedure, you are not driving the car....You are not even touching the steering wheel so the motor for the power steering would not use any power at all even if you didn't pull the fuse (only the controller would be).

If you look at the service manual on page 17-16 under the section of "EPS indicator" it states: "Even though the system is operating normally, the EPS indicator will come on under the following conditions:

When the vehicle is barely moving, 0.62MPH or stopped, and the engine speed is 2000 RPM or higher for approximately 6 minutes."

That is why the fuse is pulled....

JoeCVT = Just your average CVT owner

dtlee

· #66 · Mar 27, 2008

JoeCVT, damn I hate being wrong. I shouldn't have assume what I did. I wonder what's the story behind throwing the EPS code in those conditions. Like, what's the point.

b1shmu63

· #67 · Mar 27, 2008

If you put an ammeter on the electric assist steering you will find it draws little power even with the car stationary and the steering vigorously thrown around, but don't take my word, try it yourself as I'd like confirmation. Hats off to Honda for a very efficient design.

Dgate

· #68 · Mar 27, 2008

Here is a good link on the history of EPS,the different systems and how to measure the energy used.
It is three years old but still relevant.

http://www.automotivedesignline.com/howto/165600237

DGate

weslich

· #69 · Mar 28, 2008

Don't know exactly how much energy is saved by pulling the EPS fuse, but I just finished my first full tank without EPS: 94.9 MPG and 1273.2 total miles. I ran the tank dry just to see how far the car would go knowing it would be pretty good since the MPG I was getting was so high. Never thought it would travel so far. Previous mileage has recently been high 80's to low 90's so the gain has been around 5 MPG or a little over 5%. To me it's worth pulling the fuse. I've gotten used the hard steering and actually prefer it on the highway anyway.

atlaw4u

· #70 · Mar 28, 2008

Did you keep track of how many miles you were able to drive after the last fuel bar disappeared?

weslich

· #71 · Mar 28, 2008

It disappeared once at about 1200, came back on for a while and disappeared for good at about 1215.

Dgate

· #72 · Mar 28, 2008

Your 5 mpg advantage over that distance is impossible to contribute to the EPS being disabled..There are too many other contributing factors.
Not a conclusive test.

DGate

gpsman1

· #73 · Mar 28, 2008

weslich said:
Don't know exactly how much energy is saved by pulling the EPS fuse, but I just finished my first full tank without EPS: 94.9 MPG and 1273.2 total miles. I ran the tank dry just to see how far the car would go knowing it would be pretty good since the MPG I was getting was so high. Never thought it would travel so far.

Wait.... are you saying this car has a 13.5 gallon tank?
I thought the tank was 10.6 gallons?

Your math does not add up.
I just filled up for the first time.
I shoved in 10.4 gallons with 1 bar showing, but that was really, really going slowly, to top off that last gallon.
I had first click at about 9.6 gallons with 1 bar showing. First tank tho, so I don't have much experience.
Thanks.
-John

IamIan

· #74 · Mar 28, 2008

gpsman1 said:
weslich said:

Don't know exactly how much energy is saved by pulling the EPS fuse, but I just finished my first full tank without EPS: 94.9 MPG and 1273.2 total miles. I ran the tank dry just to see how far the car would go knowing it would be pretty good since the MPG I was getting was so high. Never thought it would travel so far.

Click to expand...

Wait.... are you saying this car has a 13.5 gallon tank?
I thought the tank was 10.6 gallons?

Your math does not add up.
I just filled up for the first time.
I shoved in 10.4 gallons with 1 bar showing, but that was really, really going slowly, to top off that last gallon.
I had first click at about 9.6 gallons with 1 bar showing. First tank tho, so I don't have much experience.
Thanks.
-John

It is a 10.6 Gallon Tank... he over filled it... the theory is that extra gas when filling at the right angle can fill into the Vapor Recovery .... about 14 gallons is the upper limit... others have done this too:

Sorry , tried to post some links... the forum is editing them and preventing them from working...

The record for a single tank of gas in an Insight is 14.0 Gallons and traveled 2,254.4 miles on that one tank... it was a contest , not a daily commute.

weslich

· #75 · Mar 29, 2008

Yes, I overfilled the tank. My best guess is about 13.4 gallons. That's 13.1 gallons at the pump plus about 1/3 gallon I splashed in just to get me to the gas station. Don't know how anyone could squeeze in 14 gallons, unless they stood the car on end. That's an idea!

You're right, Dgate, the test is not scientifically conclusive. There are too many variables that cannot be controlled. You wouldn't think that the power saved from a disabled EPS would equal a 5 MPG difference. But the best I had ever done up to that point was 90.4 MPG on a single tank under similar conditions. One thing I noticed during the run was that the SOC remained near 100% and during those times that the car got it's best mileage, exceeding the readout limits many times. Is there some relationship between the SOC and lean burn efficiency or less drag or just my imagination?

ikhoudvanu199

· #76 · Mar 29, 2008

my conclusions from pulling the fuse for a few days and putting it back in:

there is not conclusion that can be made at this time

no matter where you live(as long as its in the northern hemisphere), its getting warmer out...warmer temperatures will always equate to better gas mileage...even so much as 5-10F can make a huge difference. I have been realizing this as I am watching my trips go from their winter low of about 55mpg, up to 60mpg, now I am getting 65+mpg, etc, and soon I will be back to my summer high of 80+mpg

so I think we need to wait till the weather evens out a bit for us to make any kind of true conclusions

TRI

· #77 · Jun 19, 2010

I did a test today and didn't see any benefit from pulling the fuse. mpg on my 13 miles trip was the same in both scenarios. I did NOT see 5 mpg. Without EPS it even consumed a little bit more because I had to brake for another car one time from 30 to 0 mgh more than on my drive with EPS. So I would call it about the same and not really measureable.
Just because the fuse is 40A doesn't mean that this amount of current is being constantly drawn.

I've pulled the rear fogger fuse because this is being switched ON automatically and the current is high and for prolonged periods.

RobertSmalls

· #78 · Jun 19, 2010

On a related note, does anyone have an amp-hour meter they can install on the EPS circuit and run during real-world driving? Anybody know how to build a cheap Ah-meter?

Mike Dabrowski 2000

· #79 · Jun 19, 2010

The EV guys use a device called link 10 E-meter
Gages
When your done with it, save it for your first EV.

IamIan

· #80 · Jun 20, 2010

Mike Dabrowski 2000 said:
The EV guys use a device called link 10 E-meter
Gages
When your done with it, save it for your first EV.

I think the large LCD EV version of the Cycle Analyst gives more meter for your money.

The Cycle Analyst Homepage - Ebike Amp-Hour and Watt Meter

61 - 80 of 83 Posts

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