Electric Power Steering
#21
05-25-2009, 03:53 PM
Re: Electric Power Steering
Gary- The pull-drift compensator has a torque sensor on the steering wheel to measure how much torque the driver is inputing. I have the Helms workshop manuals for my 2005. I can't find the page number for the steering wheel torque sensor. Can you direct me to it? Maybe a small mod would give me more "compensation".
I really put it to the test Monday driving though Nebraska.
Had 45-63 ( as per radio station ) MPH cross winds for like 8 hours.
I was putting in a couple ft./lbs of torque to the side for hours.
I had to trade arms every few minutes.
It was very fatiguing.
The steering wheel torque sensor measures driver input torque. If the torque is in the same direction ( not a curvy road ) for 20-30 seconds, the EPS is supposed to input additional torque in that direction, so the driver doesn't have to, or has to input less. This is the definition of "pull-drift compensation".
I can't speak to later models, but I'm 99% sure this compensating software is not in the 2005's. I've emailed one of the Ford representaives in the article about the "new" pull-drift compensting EPS. We'll see if he replies.
Why do you think the Ford engineers are calling it "new" if it came out 4 years ago?
I really put it to the test Monday driving though Nebraska.
Had 45-63 ( as per radio station ) MPH cross winds for like 8 hours.
I was putting in a couple ft./lbs of torque to the side for hours.
I had to trade arms every few minutes.
It was very fatiguing.
The steering wheel torque sensor measures driver input torque. If the torque is in the same direction ( not a curvy road ) for 20-30 seconds, the EPS is supposed to input additional torque in that direction, so the driver doesn't have to, or has to input less. This is the definition of "pull-drift compensation".
I can't speak to later models, but I'm 99% sure this compensating software is not in the 2005's. I've emailed one of the Ford representaives in the article about the "new" pull-drift compensting EPS. We'll see if he replies.
Why do you think the Ford engineers are calling it "new" if it came out 4 years ago?
Steering System - Escape Hybrid
The electrical power assist steering system consists of:
• power steering control module
• electric motor
• torque sensor
• rack and pinion steering gear
Additionally, on page 211-00-15 in the Priciples of Operation the torque sensor is described as being between the steering colum shaft and the steering gear. DTC B2278 is torque sensor malfunction.
If drift/pull compensation is not already there, one would think it could be incorporated with a software change to the power steering control module.
EDIT: Actually, if there is a torque sensor and variable power assist that depends on it, then you definitely have some degree of pull/drift compensation by definition. But you also have vehicle speed as an input, and the assist decreases with speed.
Last edited by DesertDog; 05-26-2009 at 10:43 AM. Reason: clean up
#22
05-25-2009, 06:46 PM
Ridiculously Active Enthusiast
Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: Electric Power Steering
Don't know, can't say for certain about the FEH, but Toyota EPS uses a torque tube as a mechanical connection with a position sensor at each end of the torque tube. If the two position sensors signal differs then the torque tube is twisted in an effort to turn the front wheels. The phase and magnitude of the differential signal is used to drive the electrics.
Last edited by wwest; 05-25-2009 at 06:48 PM.
#23
05-25-2009, 07:37 PM
Re: Electric Power Steering
Sounds like this mysterious torque sensor is in the EPS module along with the motor. Since Helm, Inc. now has the '09 shop manual in stock(so much for their email notification system!), I'll find out what it says about the EPS.
#24
05-26-2009, 12:16 PM
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Join Date: Mar 2005
Location: All over the Central U.S.
Posts: 3,616
Re: Electric Power Steering
Here is a BIG difference between my 2005 FEH and my 2000 Honda Insight.
On an Interstate with a gentle, constant radius curve ( like making a 90 degree turn in half a mile or longer ):
In the Honda Insight, I can turn the wheel to initiate the curve, then I can remove my hands from the wheel, and the Insight will continue to turn on the exact same radius.
In the 2005 Ford Escape Hybrid, if I turn the wheel to initiate the curve, and take my hands off the wheel, the steering returns to center, and the car travels straight ( and off the road if me, the driver does not input torque to turn the wheel to match the road radius).
I have tried to experiment, and indirectly detect "drift-pull" compensation in the 2005 FEH and to date, have not found any data to support its implementation.
On the other hand, it appears Honda was using this "feature" back in 2000 and perhaps prior. The Honda Insight detects my constant input torque over a few seconds on my long radius curve, then, applies some like torque in the same direction so I no longer have to. This is not found in my FEH.
HTH,
-John
To clarify, both cars have what is called "EPS" or electric power steering.
My email to the Ford engineer in the article on this was never answered.
On an Interstate with a gentle, constant radius curve ( like making a 90 degree turn in half a mile or longer ):
In the Honda Insight, I can turn the wheel to initiate the curve, then I can remove my hands from the wheel, and the Insight will continue to turn on the exact same radius.
In the 2005 Ford Escape Hybrid, if I turn the wheel to initiate the curve, and take my hands off the wheel, the steering returns to center, and the car travels straight ( and off the road if me, the driver does not input torque to turn the wheel to match the road radius).
I have tried to experiment, and indirectly detect "drift-pull" compensation in the 2005 FEH and to date, have not found any data to support its implementation.
On the other hand, it appears Honda was using this "feature" back in 2000 and perhaps prior. The Honda Insight detects my constant input torque over a few seconds on my long radius curve, then, applies some like torque in the same direction so I no longer have to. This is not found in my FEH.
HTH,
-John
To clarify, both cars have what is called "EPS" or electric power steering.
My email to the Ford engineer in the article on this was never answered.
Last edited by gpsman1; 05-26-2009 at 12:29 PM. Reason: clarification
#26
05-26-2009, 07:56 PM
Re: Electric Power Steering
Returning to center, whatever sort of mechanism moves the tie rod ends is principly a function of caster. My TR-3 had so little caster, that it didn't return to center on it's own.
#28
05-27-2009, 09:56 AM
Ridiculously Active Enthusiast
Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: Electric Power Steering
Yes, sports cars are often set up that why. My '78 911 was as tiring to drive any distance as was my C210 to fly until I had the alignment changed for cross country cruising.
#29
05-27-2009, 04:59 PM
Re: Electric Power Steering
I found my FEH tracks a little better on the highways with narrower tires (225/75-16) than the stock 235/70s. Interestingly, its handling/turn in is also better with this size, but I think that is due to a different tread compound. I'd imagine 215/75-16 tires would also track well, but there are only a few that are made in that size.
#30
05-27-2009, 06:42 PM
Re: Electric Power Steering
Good discussion guys,
I have a parts page from Ford (7/26/04...5/01/06) that has the Steering rack listed as part 3504.. I'm wondering if the 08 and 09's use the same steering rack, anybody have a parts identifier book?
Do we have confirmation on pull/drift as it applies to the the first 3 years of FEH's?
Thanks
Mike
I have a parts page from Ford (7/26/04...5/01/06) that has the Steering rack listed as part 3504.. I'm wondering if the 08 and 09's use the same steering rack, anybody have a parts identifier book?
Do we have confirmation on pull/drift as it applies to the the first 3 years of FEH's?
Thanks
Mike
