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05-29-2011, 10:30 PM | #37 |
Drives: Yaris HB Join Date: Sep 2010
Location: West Buttcrack, MN
Posts: 59
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Curiosity got the best of me today so I pried the 50 amp fuse out of the fuse panel and gave manual steering (aka: armstrong steering) a try. I have to admit that I was impressed with the improved handling on the highway. Keeping the Yaris going straight is full-time job with the EPS, it's much better without.
BUT...... Under 30mph it was just way too much work and in my opinion, somewhat unsafe. Manual steering in just about any other car needs less effort and yes the steering wheel is too small for manual steering. Still, it would take more than a big steering wheel to make it tolerable on a daily basis. Having a system to attenuate the EPS at higher speeds might be the answer. I really like the effect on the highway but that's where it ends.. |
05-30-2011, 09:42 AM | #38 |
toyota
Drives: 2007 Yaris RS Blazed Join Date: Oct 2006
Location: toronto, canada
Posts: 3,637
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zebra: now you know why im planning a switch option..but worried about turning this on and off while driving...
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If my calculations are correct, when this baby hits eighty-eight miles per hour... you're gonna see some serious shit!!!!!! "Horsepower is how fast you hit the object. Torque is how far you move that object.." |
05-30-2011, 10:03 AM | #39 | |
Drives: Yaris HB Join Date: Sep 2010
Location: West Buttcrack, MN
Posts: 59
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Quote:
I wouldn't worry about the power spike.... |
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05-30-2011, 11:24 AM | #40 | |
always toyin'
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Quote:
-toy
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- Procrastinators of the world unite! ...tomorrow. My Garage.. 'Mild' Drop & Misc..2-DIN GPS/Navi..DIY:Rear Wiper Delay..Ramps/Roll-Ups..Rain Sensing Wipers / Auto-Headlamps |
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08-07-2011, 04:24 PM | #41 |
Drives: Yaris Sedan 5MT Join Date: Oct 2008
Location: SoCal
Posts: 865
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I like this thread!
Marcus and CTScott. What is the unit that adjust to speed levels...ie more power when you're not moving vs less when you're at speed? Is there any way to just affect that unit? Like telling it to give no power at all after a certain speed? As for the switch, where in the line would you put it, between the unit and the fuse or do it in the fuse box? Lastly...CT...I know you have ideas! Where are you at on this subject?
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08-08-2011, 10:27 AM | #42 |
1NZ-6spd
Drives: '05 6-Spd Vitz RS Join Date: Oct 2008
Location: Oshawa, Ontario, Canada
Posts: 2,967
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There's a torque sensor built into the steering column that senses how much force is being applied to turn the wheels and adds more or less power to the motor to assist.
I dont know if CT has experimented with adding resistance to the output ifthe sensor to tell the system not to add as much power. |
08-08-2011, 12:17 PM | #43 |
ULTIMATE
Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008
Location: USA, CT
Posts: 13,460
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From what I have found in my experimentation, fooling the PS ECU in regards to vehicle speed is not enough. I actually have to also override the torque sensor data. The "highway wander" is a good example of why this is necessary. Even at high speeds, there is enough power assist that small changes in the torque sensor feedback result in steering adjustment.
One of the simplest implementations may be to add a DPDT relay in line with the power steering motor leads, and control the relay based on vehicle speed.
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08-08-2011, 12:29 PM | #44 |
2ZR swap. DO IT! Ask how!
Drives: 09 Meteoric Metallic HB Join Date: Feb 2011
Location: West Michigan
Posts: 2,333
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If you want to just add an on/off switch that won't mess with the existing wire harness you could get an external fuse holder, 50A relay and a toggle switch. The toggle switch would be connected to the battery or accessory line and the coil of the relay, and the switch of the relay would enable/disable the power steering fuse. I'm assuming that the power steering is still 12V, so pretty much any automotive relay with 50A contact rating would work. The toggle switch can be anything that can handle 12-14V and whatever the coil current of the relay is. You would have to pull a pair of wires through the firewall, but that shouldn't be too hard either.
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08-08-2011, 12:31 PM | #45 |
2ZR swap. DO IT! Ask how!
Drives: 09 Meteoric Metallic HB Join Date: Feb 2011
Location: West Michigan
Posts: 2,333
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Is this something that could be based on the "vehicle speed" wire on the radio harness? I've only got a basic electronics knowledge at the moment, but I'm sure there's an IC that can read the pulses from this line.
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08-08-2011, 12:37 PM | #46 |
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Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008
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If you wanted to do it without a microcontroller, you could use a frequency to voltage converter IC and then feed that through a comparator.
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08-09-2011, 03:51 PM | #47 | |
2ZR swap. DO IT! Ask how!
Drives: 09 Meteoric Metallic HB Join Date: Feb 2011
Location: West Michigan
Posts: 2,333
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Quote:
I'm also guessing that the signal is 12V, so you'd have to use a regulator or voltage divider to get down to the 5V input that the F/V chip is expecting. I'm still looking through the datasheet to see exactly how the F/V converter works. Any suggestions on what kind of comparator would be the right type to use? |
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08-09-2011, 04:19 PM | #48 | |
ULTIMATE
Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008
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Quote:
For the comparator, a general purpose one, like the LT1011 would be fine. It is amazing how much more complicated this gets trying to do it with analog, rather than digital. I should just build you up one to experiment with using a microcontroller. I could make a simple little black box that connects to ignition switched power and then has an output to drive the relay coil. I could have a pot on the box to adjust the switch over speed.
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08-09-2011, 04:37 PM | #49 | ||
2ZR swap. DO IT! Ask how!
Drives: 09 Meteoric Metallic HB Join Date: Feb 2011
Location: West Michigan
Posts: 2,333
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Quote:
I looked at the EWD and the power steering is already throttled by the ECU based on speed and the torque sensor. According to p 176 of the EWD: Quote:
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08-09-2011, 04:55 PM | #50 |
Drives: 2015 H Production Yaris Join Date: Oct 2009
Location: Debary, FL
Posts: 1,953
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I like elec power steering. It rocked in my RX-8, made it one of the most pleasurable cars to autox - past cars I raced with traditional systems always struggled to keep up, our Corvette use to puke power steering parts regularly.
I think the system in the Yaris works great. In the GT/B-Spec cars it works seamlessly, I had no problem on the track with it. I hated the H Prod car when we first started racing it... Due to some hacked wiring the system never worked, and with a 10" wide slick the car was a beast, always fighting you in the turns. However, with time we were able to work out some of the steering bind, making it easier to drive. Ditching the elec motor and the stock column made it much easier to turn (still not as good as the EPS system), and it actually dropped a good bit of weight. No brainier for me, in a street car I would keep it.
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2005-2008 SCCA Solo BS National Champion 2017-2018 SCCA H Prod National Champion |
08-09-2011, 08:26 PM | #51 | |
ULTIMATE
Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008
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Posts: 13,460
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Quote:
It actually sounds like it is better for track than street. The primary complaint about the EPS is how it induces wander at highway speed.
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08-09-2011, 08:31 PM | #52 | |
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Quote:
I just mean based on the overall number of components and the little bit of math required for configuring the comparator, etc. The P/S light id turned on by the combination meter when the EPS reports an issue. If the EPS isn't alive it can't complain.
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08-10-2011, 08:43 AM | #53 |
2ZR swap. DO IT! Ask how!
Drives: 09 Meteoric Metallic HB Join Date: Feb 2011
Location: West Michigan
Posts: 2,333
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Understood. For an entry level EE student like me, the more cost effective solution would be using components and a breadboard instead of a PLD. Most of us DIY-ers don't have access to a programmer. The only microcontroller I've been exposed to so far comes on a $150 dev board, and that's a bit too expensive to cloister in a box under the dash. =)
Last edited by CrankyOldMan; 08-10-2011 at 11:40 AM. |
08-10-2011, 10:18 AM | #54 |
Drives: Yaris Sedan 5MT Join Date: Oct 2008
Location: SoCal
Posts: 865
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...it's like watching soft core.
Keep going!
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