Suspension, Brakes, Drivetrain discuss the wondrous effects of boost and your miata...
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EPS conversion

 
Old 02-09-2019, 10:34 AM
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Default EPS conversion

Sammy Valafar and his crew appear to have an EPS conversion for the NA/NB now. I don't know anything about it and we're not selling them. Just an FYI.

Facebook link https://m.facebook.com/story.php?sto...00000482697325
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Old 02-09-2019, 11:08 AM
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I think that setup could be the ticket for people with swapped engines (like an ls). A notched-depowered rack will fit an OTS dry sump pan as far as I know. And as shown by many, a track driven LS is usually just a time bomb without a dry sump. I'll personally be picking one up in the next year or so.
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Old 02-10-2019, 12:37 PM
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We have one on order to evaluate. It will go into my race car. Will report findings in a few months.
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Old 02-11-2019, 04:50 AM
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It would be cool if it could output the steering angle and the load for idle correction through CAN. I would do it in a heartbeat if it did.
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The “into to megasquirt thread” mentions that the MS3 basic has 5 inputs with built in pull up resistors - and I was just wondering why it would have so many, while the MS3Pro PnP has just 2 (with no pull ups?)
MS Labs: Plug and Play Megasquirt ECUs for ANY 90-05 Miata (NA, NB1, NB2 w/VVT, MSM), including basemaps to get you started ASAP. PM me or email or details.
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Old 02-11-2019, 11:29 AM
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Originally Posted by Reverant View Post
It would be cool if it could output the steering angle and the load for idle correction through CAN. I would do it in a heartbeat if it did.
That's what I am hoping for. If the system turns out to only function in dumb mode it'll still be nice. But if we can actually build some 2D maps, use VSS and steering angle, that would be sweet. Hello 5.5° caster on 245's.
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Old 02-11-2019, 07:38 PM
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Looks similar to what I built for the exocet last year. They just cut the column and use the front firewall mount floating and have that bearing support the shaft/assy. Mine for reference. It's about $150 in parts. For his crazy price I should start making them to sell. Replaced lower end and used the actual EPS shaft as the new lower, remove stock lower column bearing and add a 3/4x1 3/8 bearing, which is the EPS shaft dia. Saves a heap of money. PS is "dumb" because it runs in fail-safe mode but has good feedback. I have a prius module in mine. YRMV.

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Old 02-13-2019, 10:16 PM
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Worth noting they use Equinox/Vue EPS units which are overboosted compared to the toyota/kia units, however they do have a potentiometer built in (looks like they use an extension lead and **** - they're built on the board at the factory) so you can adjust the assist to what works for you. All of the sensors/motors are typically made by denso. The overall package is really nice - a lot nicer looking then mine is.
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Old 02-14-2019, 03:34 PM
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dbl post

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Old 02-14-2019, 03:35 PM
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Shot of the 3/4" ID * 1 3/8 OD bearing in the miata shaft front housing (Ebay, $8). It bolts to the firewall just like the stock column and acts as a floating front support. Pictured on the 3/4" EPS shaft.





Like I said, about 150 in parts. I don't want to take away from the kit being offered because the fit and finish of theirs is very nice and admittedly much nicer then mine - but the price range will put it out of reach of some. You CAN do this yourself if you have access to a welder (person) or welder (device).

Edit: Here's the original article I used last year to dial in my gain. It talks about the potentiometers, the controllers, the signals, and how they interact. It may help some of you wanting to use megasquirts.

http://www.autospeed.com/cms/article...ering&A=111532
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Old 02-18-2019, 10:28 AM
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Old 02-18-2019, 09:02 PM
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Had a long chat with Ken, the guy that builds these EPS units here in California.
epowersteering.com

My basic question was if there was a CAN input available to control boost. Sadly, there isn't. But the units are force sensitive. He doesn't have the force I/O range mapped but is going to do that for us. The Automatic version of the kit is basically full boost all the time. Not good for a track car.
The version we are all interested in has a manual adjuster **** a potentiometer. The **** has no detents but the EPS control unit recognizes 10 steps of resistance and translates those to 10 distinct level of boost. The pot basically mimics what the stock cars PCM did from VSS and rpm.

So I asked if he could build an arduino to convert a 0-5v analog input into specific ohm resistance. He said, no problem. So we can then use a VSS input (ABS tone rings or NB trans output shaft speed) & rpm into a 2d table to generate our "speed sensitive" steering.

Looking forward to getting ours in a car and playing with it.
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Old 02-19-2019, 01:40 AM
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Originally Posted by emilio700 View Post
Had a long chat with Ken, the guy that builds these EPS units here in California.
epowersteering.com

My basic question was if there was a CAN input available to control boost. Sadly, there isn't. But the units are force sensitive. He doesn't have the force I/O range mapped but is going to do that for us. The Automatic version of the kit is basically full boost all the time. Not good for a track car.
The version we are all interested in has a manual adjuster **** a potentiometer. The **** has no detents but the EPS control unit recognizes 10 steps of resistance and translates those to 10 distinct level of boost. The pot basically mimics what the stock cars PCM did from VSS and rpm.

So I asked if he could build an arduino to convert a 0-5v analog input into specific ohm resistance. He said, no problem. So we can then use a VSS input (ABS tone rings or NB trans output shaft speed) & rpm into a 2d table to generate our "speed sensitive" steering.

Looking forward to getting ours in a car and playing with it.
Generally the vss is input as a sine wave. The controller recognizes the pulses from vss on the neutral ignition connector. ABS rings would work, as would shaft speed.

Emilio you might find this page interesting, specifically the power steering manual referenced in it. Both the prius/yaris and gm/saturn EPS units use denso controllers. They all work in the same manner when it comes to vss inputs.

https://mgaguru.com/mgtech/steering/sr302.htm
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Old 02-19-2019, 11:36 AM
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The Prius unit, to the best of my knowledge, operates in failsafe mode when disconnected from its native CANbus. Meaning it is maximum boost with little force sensitivity. The GM unit retains force sensitivity. The test that Ken is doing for me is to determine how the pot is decreasing output torque.
Does it just cap peak torque delivering a slope with a flat top or does it change the entire slope? Like the difference between an inline proportioning valve or bias bar on the pedals.
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Old 02-19-2019, 01:21 PM
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Update: Ken checked the I/O signals for the current Arduino board and it turns out, the pot outputs a 0-5v analog signal that the board converts into resistance values. This means one can configure a programmable ECU to output a signal for tuning the speed sensitivity and overall boost. Just need
to figure out how to get a VSS signal, via either the NB2 speedo sensor, ABS tone rings or DIY hall sensor on the driveshaft. It occurs to me that one could not only build a 3d map for steering boost but also set up a two position switch on the dash for wet/dry settings. Neat.
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