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throttle by wire


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danielhitch 
Member - Posts: 5
Member spacespace
Joined: October 01, 2006
Location: United Kingdom
Posted: April 30, 2007 at 1:44 PM / IP Logged  
Hi.
I am currently converting my car to run on bike throttle bodies... The bodies are throttle by wire but my car just has a normal throttle cable... I am going to be getting an aftermarket ecu (emerald)... I was just wondering if any of you know if it is possible to convert the car to a throttle by wire system instead of a cable driven system??
bellsracer 
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Posted: May 01, 2007 at 10:51 PM / IP Logged  

It is possible to do so. In fact, there are some production cars (luxury cars of course) that already have them equipped (07 Mazarhati [sp?], 07 Bentlys, etc) And if I am not mistaken, the Cooper SS is also TBW.

Never send your ducks to eagle school.
The difference between ordinary and extraordinary is that little extra.
The 3Ls of life: Learn from the Past, Live for the Present, Look to the Future.
KPierson 
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Posted: May 02, 2007 at 10:24 AM / IP Logged  

Typically, performance oriented people go the other way - convert dbw systems back to throttle cable systems, as the dbw system offers you no real advantage, and adds a layer of complexity (and possibly unreliability).

In order to run a drive by wire system you will need:

Accelerator pedal with as least two different output signals (outputs can be offset, inversed, or a ratio, but shouldn't be exactly the same)

A throttle body that has an electronic motor on it (which you have) and has a built in TPS (throttle position sensor).

You will then need a computer that will read in your accelerator pedal and control the throttle position while monitoring the throttle position in real time.  Each throttle body will need its own input and output to the computer.

Kevin Pierson
bellsracer 
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Posted: May 02, 2007 at 5:37 PM / IP Logged  

I would disagree with you on that. TBW systems are not that complex. They are essentially servos and potentiometers. Depending on the vehicle and how the engine is setup, TBW would actually be safer and easier to work with. I find this particularly true with mid and rear engined vehicles. Wtih minimal parts moving aginst each other there is less wear and -more often than not- less chance for stuck throttles. I know that some monster truscks for example use TBW systems so it becomes much easier to maintain and work with (albeit a bit more exspensive, but that is why they have sponsors) I don't know which ones exactly have it, but I think itmight become the next standard in automotive design. a TBW/DBW system would allow for near infinite possibilities in design and ergonomics. Complexity and reliability will all depend on the installation just like everything else.

As for the TPS, there are some systems that do not need them, again getting their control and response from the potentiometer(s) in the pedal (stick) sensors.

The best way to look at this is to think of a RC gas car. At its heart, it is essentially the same thing. A signal comes in and says "the throttle should be here" and the servos/motors get to the proper position. Depending on the system, a TPS isn't even needed for potentiometer based servos. It just becomes a matter of reproducing a control normally operated by a cable/wire.

I say, if you want to do it, then just try and go for it... Do your homework, plan each step before you begin, and of course, have fun. The only reason we have light bulbs today is because Edison didn't let the "there is too much to it" thinking even begin to come into his mind.

Ganbatte ne!

Never send your ducks to eagle school.
The difference between ordinary and extraordinary is that little extra.
The 3Ls of life: Learn from the Past, Live for the Present, Look to the Future.
KPierson 
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Posted: May 02, 2007 at 6:06 PM / IP Logged  

How can you disagree about the comlexity of a simple cable vs. a completely computerized system?

A thottle cable is the most basic you can get.  I'm not saying that DBW systems are rocket science, but side by side there is much more to them. 

I highly doubt you will ever see a production vehicle without a TPS sensor on a DBW car.  DBW systems are built to be redundent and failsafe.  If any part of the system were to fail the ECU should be able to detect the failure immediately and prevent engine damage (through fuel/spark cut).  Without a throttle position sensor if the throttle motor were to break or stick the ECU would have no way of monitoring it.  at least on a throttled car you KNOW when the throttle is stuck based on pedal position - it gives the operating feedback and the ability to shut the motor off in order to protect the motor.

I've never seen an aftermarket DBW controller.  They may exist, but if they don't that will add one more layer of complexity as you will have to build one!

Kevin Pierson
bellsracer 
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Posted: May 03, 2007 at 6:52 AM / IP Logged  

A throttle cable may be as basic as it gets, but the TBW systems "complexity" is no more than an ECU reflash in upgrades.

After doing some some extra footwork I also found that this technology is a LOT more common than I previously stated. Just about all luxury cars now have the system standard and it is now even found in the economy cars. The redesigned 07 Chevy Aveo now features it as a standard option.

Advantages to these systems include (but not limited to) faster throttle responses, increased fuel mileage, lower maintanence costs, and increased reliability from lack of mechanical wear.

To be honest I was surprised how the system works. Similar to Fly-by-wire systems used in aircraft, there is no direct control of the acceleration of the vehicle. Rather it takes in what the driver/pilot wants and then calculates what would be the best way to achieve the result. With just about every 1990+ vehicle on the market now there is some sort of computer controlled system in place on the vehicle. (information courtesy of the shop owner)

Lastly, what is wrong with people wanting to try and build upgrades and modifications to their vehicles? Quite frequently, I see people downing an idea or discouraging an idea by stating that something is too much or not worth it. It is evident in several parts of 12volt.com. It's rather annoying. I this forum was for the exchange of ideas and help each other gain the knowledge and ability to make what is in our hearts.

Yes there are two sides to every coin, and I understand the fact that they must be acknowledged. So acknowledge them, but don't present them in a way that makes the idea seem like it is a bad idea.

I feel sad for the several threads that have this problem in it.

Never send your ducks to eagle school.
The difference between ordinary and extraordinary is that little extra.
The 3Ls of life: Learn from the Past, Live for the Present, Look to the Future.
danielhitch 
Member - Posts: 5
Member spacespace
Joined: October 01, 2006
Location: United Kingdom
Posted: May 03, 2007 at 7:19 AM / IP Logged  

Thanks for the responses guys. The Emerald system isnt just a flash reprog.. its a 3d mappable management system designed to give various outputs in relation to various inputs. I am going to try and make up a pedal pot for my car using the parts from an Audi A3 which uses a tbw system (the parts are reasonably cheap too). It shouldnt be too difficult. The reason why I am thinking about using tbw as opposed to just a cable driven system is that the bike bodies that I am using have a steeper sweep than a standard car body. This will lead to quite a jerky acceleration if I would convert the system to cable driven. With tbw, this problem should be solved to  a great extent. I shall keep you guys posted with what happens.

Thanks.

KPierson 
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Posted: May 03, 2007 at 7:32 AM / IP Logged  

DBW is everywhere, I learned that when it was in my '06 base model F150.  My '04 G35 has it, also.

I wasn't discouraging the idea, I told him what was needed and made a simple observation that most people go the other way when performance is the issue.  This obeservation is based off of my own car and performance upgrades (built bottom end twin turbo G35).  The DBW system in my G35 has kept large, repuable companies like AEM from building stand alones for the 350Z/G35 community because of the liability involved.  Because of the DBW system we have been forced to use piggy back style controllers.

I never tried to talk him out of it, I never said it was a bad idea, I never said anything negative against it.  I think you read my post wrong.

I did some research in the Emerald unit and it does not have the ability to do DBW.  So, you will need something like the Audi.  You'll of course need the pedal and the actual controller, unless you are going to build your own controller.  A quick Google search turned up no aftermarket DBW controllers.

I did find this, though, which was fairly informative: http://www.picotech.com/auto/applications/electronic_throttle_control.html

They go on to say that some of the benefits are fuel economy and emissions.  You'll need to set the unit up to disregard these  two 'benefits' for a performance application.  We all know that 'fuel economy' and 'emissons' don't go well with 'performance'.

One thing I would look in to before settling on the Audi system is if the Audi controller is programmable (if that is what you are going to use).  You'll need to reprogram the controller output to drive your throttle bodies it sounds like.  I know the DBW maps on the 350Z/G35 are reflashable.

I would like to see a study comparing breakdowns from throttle bodies vs. DBW systems.  Sure, you eliminate a mechanical cable but you're adding enough electronics/servos to introduce a whole seperate point of failure.  I would guess in a car <10 years old the failures between the two would be very close. (pure speculation on my part)

Keep up updated and good luck, it sounds like you've got quite a bit of work ahead of you!

Kevin Pierson
rudy1980 
Member - Posts: 3
Member spacespace
Joined: March 23, 2007
Location: United States
Posted: May 08, 2007 at 1:03 AM / IP Logged  

DBW is very common nowadays my mom's '04 Tundra has it and I believe all RSX's have it.  It works the same as the TPS (by measuring voltage) the further you press the accelerater the more voltage is output (on a Honda it .5V-5V).  So essentially you should be able to connect your exsisting throttle cable to a TPS (or pot.) to drive the motors in the throttle bodies.

Good Luck

P.S What kind of car are you modifying and where did the throttle bodies come from?

KPierson 
Platinum - Posts: 3,527
Platinum spaceThis member consistently provides reliable informationspace
Joined: April 14, 2005
Location: Ohio, United States
Posted: May 08, 2007 at 3:56 PM / IP Logged  

As stated above, there are ALWAYS two signals that are somehow related, but not exact in the pedal.  Some of them are inversed, some are offset, etc, but there are always two.

Second, you wouldn't want to connect the pedal (pot) directly to the motor.  It wouldn't work.  You would not be able to reliably put enough current through the pot to move the motor fast enough.  This type of circuit should only be used as an input in to a computer system (very low load). 

Kevin Pierson

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