Drive-By-Wire Solutions

[winders]

I upgraded the ITBs for my race car (AT Power) and needed a Drive-By-Wire (DBW) setup. AT Power have a DBW solution using a single servo but, for whatever reason, it would not work properly with the MoTec M150 ECU I am using.

So, I had to look for other solutions. My tuner recommend I try a Bosch-based solution from EFI Hardware in Australia. He also said that he preferred a servo for each bank instead of a single servo setup. I had to design and make the mounting system and modify the linkage arms so that each bank behaved the same.

Here is the result:



The aluminum plate the servos are mounted to is .250" thick. It is mounted to a JB Racing breather cover with a AN-16 fitting. I used two dowel pins to locate the mounting plate on the cover.

[Uwon]

Any pics of the accelerator pedal end?
Johan

[Nditiz1]

This looks pretty slick. What's the cost is associated with this setup?

[safe]

I like! I want it!

Do you have a TPS on each bank or is there a TPS in each servo so the ECU can keep them synchronized?

[winders]

Originally Posted by Uwon

Any pics of the accelerator pedal end?
Johan

[winders]

Originally Posted by Nditiz1

This looks pretty slick. What's the cost is associated with this setup?

Well, you need an ECU that supports dual DBW servos.

The EFI Hardware servos cost about $725 each:

https://www.efihardware.com/products/3196/drive-by-wire-actuator-dbw

The linkage rods cost something as does the wiring and then you have to set up a PID for them in the ECU configuration. That is best done by a pro.

[winders]

Originally Posted by safe

I like! I want it!

Do you have a TPS on each bank or is there a TPS in each servo so the ECU can keep them synchronized?

Each EFI Hardware servo has two TPS. One for "main" and another for "tracking". So there are 4 total in the setup. Then you have "main" and "tracking" position sensors for the throttle pedal.

It seems that the consensus these days is that it is better to have the position sensors on the servo(s) than on the ITBs. This is assuming the ITBs have strong enough return spring to close the ITBs if there is a sensor issue. This eliminates any free play issues you might have with the ITB linkage.

[PeteKz]

Nice work. Please let us know how well it works on the track.

[blue911rsr]

So where is your pedal sensor looks like you still have the cable ?

[winders]

Originally Posted by blue911rsr

So where is your pedal sensor looks like you still have the cable ?

That was a photo from last year. Here is a newer photo:



You can see the green Variohm TPS.

[Tom '74 911]

Scott,

That's super cool and interesting, what you're doing. I'm interested to hear how it feels on the track, especially how it compares to your previous setup. Kind of apples to oranges, but my daily driver VW Golf R is drive-by-wire and there are some funny things about it... how the throttle pedal feels sometimes, how responsive it is etc... It probably has a lot to do with the ECU and how it's programed - one funny thing is that you can't be on the throttle and brake at the same time. If you brush the brakes and don't lift off the throttle, the ECU automatically cuts the throttle, and there's a lag before it picks up again when you get off the brakes. Anyway, lots of tuning options likely available... I'm interested to hear about how it feels and how much fiddling it takes to work it out.

Tom

[winders]

Tom,

The MoTec M150 handles drive by wire far differently than a street car ECU would. From what I understand, the DBW setup is as fast responding to throttle input as a cable setup is. I can left foot brake and be on the gas and the brake at the same time. I can change the progressiveness of the throttle in software.

Cold start issues are a thing of the past. You just start the car and walk away. Rev limiting is much smoother.

[Tom '74 911]

I figured your system would likely be worked out to 10/10! Sounds like it should be awesome.

[LukasM]

That's a very trick setup with dual DBW ITBs Scott, and clean install! Does your Motec M150 handle dual DBW stock, or did you have have to upgrade the software?

(Homebuilt by) Jeff also converted his ITBs to DBW, although he used a BMW (S54?) servo to do it.

I've been thinking about doing the same on a 3.6 build, to get rid of the Motronic with the messy idle speed valve setup etc.. With a single throttle body the conversion should be rather easy, you can get a Bosch E-TB for $200 that will bolt right on, and then you can use a 997 gas pedal with the brackets from Adapt Motorsport that also bolts right in.

[winders]

Lukas,

Yes, all firmware versions support two DBW servos. The M130 does too but using two uses a lot of the power available. I am using the MoTec USA Sportscar package.

Yes, a single TB setup is much easier to deal with. These Bosch units are great:



In fact, the EFI Hardware servos I am using are based off that Bosch motor. They just make a custom housing with a different shaft setup.

Scott

[David Inc.]

Originally Posted by Tom '74 911

Scott,

That's super cool and interesting, what you're doing. I'm interested to hear how it feels on the track, especially how it compares to your previous setup. Kind of apples to oranges, but my daily driver VW Golf R is drive-by-wire and there are some funny things about it... how the throttle pedal feels sometimes, how responsive it is etc... It probably has a lot to do with the ECU and how it's programed - one funny thing is that you can't be on the throttle and brake at the same time. If you brush the brakes and don't lift off the throttle, the ECU automatically cuts the throttle, and there's a lag before it picks up again when you get off the brakes. Anyway, lots of tuning options likely available... I'm interested to hear about how it feels and how much fiddling it takes to work it out.

Tom

Yep that brake override is a safety thing so that the car will stop when someone panics and hits both pedals at once. A lot of manufacturers added that during the whole Toyota unintended acceleration scare, when they found out that it was just old people hitting the wrong pedal.

The rest of it, though, the lack of instantaneous response, is for emissions. Rapid throttle changes are bad for controlling fuel mix so they get smoothed out. If you have a manual they'll also mute the throttle during shifts so you don't destroy the clutch.

I hate those things. A lot. If they're mapped for linear response, though, they can be absolutely fantastic, so very cool to see this work!

[dannobee]

I finally finished my pedal box and dual master cylinder setup, with hydraulic clutch and drive-by-wire throttle. I used the factory pedal box and welded a few pieces of sheet metal to it to adapt a nissan 350z accelerator pedal position sensor. It all fits under the factory floor board and carpet. I wanted "stock appearing" and that's exactly what I got.

https://forums.pelicanparts.com/porsche-911-technical-forum/1160332-early-911-930-pedal-box-scrs-style-dbw-g50-clutch.html