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Discussion Starter #1
Okay, I know what a drive-by-wire system is, but what actual benefit does the MDX's dire-by-wire throttle deliver?
 

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Don't know

My 02 Toyota Tundra has it and the only thing I have noticed is the gas petal doesn't go up and down while on cruise like the old days. I'm sure there are benefits but I would never have known the truck had it if I hadn't read about it. IMHO it’s just another item on the “might fail” list and a scary one at that. I would hope that logic is built into it to just shut off the gas flow if it senses something wrong.:D

Niles
 

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Another benefit for Auto makers is that it is very easy to make right and left hand drive vehicles (read CHEAP).


It is a kind of a scary thought that the brakes aren't directly linked by a cable/hydraulic line to the pedal and there is no steering column.. But air travel is still the safest form of travel and they have been drive by wire for years and years....
 

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We're talking about the throttle only...the brakes are NOT drive-by-wire.
 

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Discussion Starter #6
Isearched for wire andthrottle, and didn't find anything other than a bunch of postings that the feature is new for 03. Any idea what thread subject I should try to locate?
 

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From the driver's perspective, it makes little difference as you will notice little change. What it does do is make it easier for the manufacturer to interface such things as cruise control, traction control, VSA and the like that need to be able to interact with the throttle.

Tom

jeffster said:
Okay, I know what a drive-by-wire system is, but what actual benefit does the MDX's dire-by-wire throttle deliver?
 

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If we're talking throttle only, then we should still have a steering column, too. I think Mercedes has a car that's fully drive-by-wire, including steering. I'm a little leary of having software in sole control of how my steering inputs get to the wheels... But on the '03 MDX, software throttle doesn't really scare me.
 

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jeffster said:
Okay, I know what a drive-by-wire system is, but what actual benefit does the MDX's dire-by-wire throttle deliver?
Actual benefits:

#1 Makes throttle response feel snappier. The amount of pressure your foot/ accelerator linkage puts on a throttle cable is not linear. Further, the angle/percentage opened of the air-valve may not be linear. Drive-by-wire/electronic throttle fixes that. Every extra "push" results in more "go".

#2 Shifting. The throttle can be eased for a FRACTION of a second as the RPMs hit the tranny's shift point. This makes the wear& tear on the tranny significant;y reduced. It allows for a bit more MPG (as the shift completes quicker) and ensures that the shifting in general feels more solid.

#3 VSC. Without electronic throttle control the VSC would need a secondary means of controlling the throttle. By using a single control method the VSC can respond quicker and more smoothly.

#4 VTM. By coordinating info from the VTM into the electronic throttle control there is a smoother transfer of power. Should make the already very smooth VTM all but invisible

#5 Idle. By employing electronic throttle control there is a greater range of idle speeds. May help for faster warm-up, reduced emissions.

#6 Data. It is much easier to use the electronic throttle control as in input to the adaptive ECM's "block learn" mode. It can measure/compute "velocity delta" for the accelerator pedal and determine when the driver is "stomping on it" versus heading up a hill. The sensors that measure throttle input are pretty simple, but when combined with a high sampling rate/clock info such correlations are easy. Much more costly/complicated to do this with inertial sensors and such.

There may be others, this from info I have gleaned from a few google searches...
 

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Hi Renov8r:

___Thanks for the detailed information … It truly sounds like it is needed for all the new vehicle stability and control features but I just hope that it never fails because it sounds very expensive sans a simple throttle cable replacement.
It is a kind of a scary thought that the brakes aren't directly linked by a cable/hydraulic line to the pedal and there is no steering column. But air travel is still the safest form of travel and they have been drive by wire for years and years...
___Dakster, the only problem is that if the plane that you happen to be flying in - fly by wire system completely fails, you will probably not be long with this world … In the MDX, you may still stand half a chance :D

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email protected]
 

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jonnygoodboy said:
If we're talking throttle only, then we should still have a steering column, too. I think Mercedes has a car that's fully drive-by-wire, including steering. I'm a little leary of having software in sole control of how my steering inputs get to the wheels... But on the '03 MDX, software throttle doesn't really scare me.
Don't have to look too far. Remember the Acura DN-X concept? Now that car had some gadgetry.
 

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Discussion Starter #12
Thanx

Thanks, renov8r -- those are some good tangible benefits.

Now if only I can find a MDX before my lease is up, in the color and trim I want! :rolleyes:
 

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Re: Re: Drive-by-Wire Throttle -- What's The Big Deal

renov8r said:


Actual benefits:


#2 Shifting. The throttle can be eased for a FRACTION of a second as the RPMs hit the tranny's shift point. This makes the wear& tear on the tranny significant;y reduced. It allows for a bit more MPG (as the shift completes quicker) and ensures that the shifting in general feels more solid.

Actually, this is rarely done using the throttle vavle since the response time is too slow. It is normally done by momentarily retarding the ignition timing.

#5 Idle. By employing electronic throttle control there is a greater range of idle speeds. May help for faster warm-up, reduced emissions.

A throttle is too coarse for accurate idle speed control and this is usually done with a separate IAC vavle.


#6 Data. It is much easier to use the electronic throttle control as in input to the adaptive ECM's "block learn" mode. It can measure/compute "velocity delta" for the accelerator pedal and determine when the driver is "stomping on it" versus heading up a hill. The sensors that measure throttle input are pretty simple, but when combined with a high sampling rate/clock info such correlations are easy. Much more costly/complicated to do this with inertial sensors and such.

Mechanical throttles use a thottle position indicator potentiometer to supply this information. The data produced is very much the same, just the method differs.

Cruise control and VSC interface is the primary reason for DBW.




 

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Our local paper yesterday had an article on the latest automotive technology, including drive by wire. Apparently electronic throttle control/drive by wire(DBW) can increase gas mileage by up to 5% due to the more efficient power/shifting control possible using this technology.
 

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I bet that is how they were able to keep the gas mileage the same while increasing the horsepower by 20.
 

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Actually......

paul123 said:
I bet that is how they were able to keep the gas mileage the same while increasing the horsepower by 20.
.......that's not necessarily true! When Acura introduced the Type-S version of the TL they increased Horsepower by 35, from 225bhp on the regular TL to 260bhp on the Type-S without any loss of fuel economy (both are rated 19city/29hwy) and FYI BOTH the TL and Type-S DO NOT
HAVE drive-by-wire throttle.
 

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Re: Actually......

vicpai said:


.......that's not necessarily true! When Acura introduced the Type-S version of the TL they increased Horsepower by 35, from 225bhp on the regular TL to 260bhp on the Type-S without any loss of fuel economy (both are rated 19city/29hwy) and FYI BOTH the TL and Type-S DO NOT
HAVE drive-by-wire throttle.
It was just a guess????
 

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If Acura is willing to put drive by wire in the MDX in Lawsuit Happy USA.

I would figure that it is pretty safe...

Does anyone remembers the Audi sudden acceleration in 80's...???

I would figure that the Acura Legal folks question the engineers a few times... :)
 

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Re: Re: Drive-by-Wire Throttle -- What's The Big Deal

renov8r said:


Actual benefits:

#1 Makes throttle response feel snappier. The amount of pressure your foot/ accelerator linkage puts on a throttle cable is not linear. Further, the angle/percentage opened of the air-valve may not be linear. Drive-by-wire/electronic throttle fixes that. Every extra "push" results in more "go".

Ok I've noticed in a couple cars including my mother's BMW that has the drive-by-wire is that throttle response it not snappier. I notice they have an extended delay from when you push the gas pedal and when you go. I find myself pushing harder thinking that it needs more gas, and then when it finally kicks in, I almost screach off the line. I don't think it is snappier at all.
 

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Mechanical connection required for steering

Mercedes has built a concept car that has steer by wire, but it will never be built for public consumption until Federal laws change. Currently Federal law says that the steering wheel must have a mechanical connection to the wheels.

Mercedes car is cool though...it is steered by a joystick. No steeringwheel at all. Would be like flying a fighter.
 
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