I've been here for a month or so now and have had a few posts. I have seen people reference the dbw with regards to the transmission a number of times. I have tried to search it but I get a message saying query is too short and nothing comes up. Can someone explain to me what dbw is or point me to a website that does so. I'd appreciate it.

TIA,
Greg

 

You mean you know DBW stands for drive by wire, but don't know what that actually means?
Think of DBW as something akin to an encoder, where the position is fed back to the controller.
The position is looked up in a chart, which tells the EMCU how long to spray the fuel into the cylinders for.
In other words, there's no linkage (direct) to the engine fueling system only a computer which tells the system what to do at any given pedal position.
This is only a small part of what DBW does - see the links below for more and use the term in google for other hits.

http://en.wikipedia.org/wiki/Drive_by_wire
http://en.wikipedia.org/wiki/Electro...rottle_control

 

Not exactly....Fuel injector timing and duration has always been PCM controlled no matter whether the veh has DBW or not. Drive by wire simply controls throttle plate position (and therefore intake air volume) by using a sensor on the accel pedal, and an electric motor on the the throttle plate....replacing a cable or linkage.

 

a pain in my ass preventing a new ecu.

 

In simple english, "a computer that has replaced the traditional throttle cable. With DBW, a driver no longer has mechanical control over the throttle plate opening, instead, the driver controls the plate thanks to electronic sensors which translate the gas-peddal position to the equivelant throttle opening."


In much simpler words:

"Mostly useless and a pain in the ass"


In the TSX:

"A f***ing disaster"

 

The worst idea in the automotive industry since friction shock absorbers.

 

DBW isn't bad by definition... Honda definitely botched it on our car, but technically, it doesn't have to be that way.

Most of the problems we have with DBW are linked to procedures in the DBW control module that have been added deliberately to control emissions, etc. The bigest pain in our @sses is the revs hanging a bit longer than we would like, and the hesitation when we get back on the throttle. Those are linked to the emission control piece of the code, that were put in to meet the emissions requirements...

 

You know what's really crazy--the plan to move to steer-by-wire and brake-by-wire! Yes, this is actually happening, just look into the bus technology that's currently in the works (FlexRay, CAN, LIN, etc). Unbelievable.

 

I agree with you for sure. However I don't think we really know if it's emissions related or not--and emissions would most certainly not benefit from a throttle that hangs open when the accelerator is released... seems that going into decel mode as quickly as possible would be the best for emissions and economy. Therefore the lag in DBW operation is just as likely to be a slow servo motor or insufficient microprocessor speed.

Generally speaking, I really question the validity of the technology.
Is it popular now because it's high tech and therefore it must be a good thing?
Is it popular now because some nauseatingly non-witty auto journalist at Car and Driver complained that his sensitive little foot could feel vibration from the engine through a throttle cable?

There has to be more than enough processing speed and headroom today to handle whatever emissions difficulties exist with a cable actuated throttle. So what is the real advantage of a DBW throttle? The only one I can think of seamless integration with stability and traction control systems. Oh yeah, and a car with DBW throttle technically doesn't need an idle air control valve...

 

I agree, its integration with the VSA is probably why

 

Agreed that it may not be best for fuel economy, but I read somewhere on the Honda site that the fraction of a second of revs allows the fuel/air mixture to be adjusted to reduce emissions, prior to revs dropping... not sure how that works, but I'm sure someone on this site will know why...

In fact, there is a recall on current Civics for that same issue. I read in Road & Track that they went through the recall, but that it didn't really resolve the issue with the revs hanging on too long...

 

DBW is the worst invention ever!

gas fed to the engine is controlled by the eco(car computer) control by your foot. the response is not instant. non-dbw is throttle cable. the gas pedal is directly connected to the engine. instant response

 

Hmmm.. physics would dictate that DBW would have faster response, since a spring-loaded cable has to fight friction and inertia to actuate the throttle body.

The DBW in comparison should be faster since the communication between the sensor and ECU is calculated in milliseconds. THe issue is the software used, and not with the electronic control...

 

Not really. We still have a physical cable to Accelerator Position Sensor just like how it is on a non-DBW setup. The signal from this APS has to relate this pedal movement to a controller and in turn, translate this movement to a signal and transfer it to the DBW TB controller. The TB controller then moves the throttle plate via the drive motor. You can test the response of the throttle plate movement in relationship to the foot pedal by removing the intake tube and watch. I would prefer a non-DBW TB.

 

More than slightly overstated, but yes, often a large pain in the ass.

 

Thanks for the info... I would have expected that they would have put the APS near the pedal assembly, with a wire to the ECU... not the other way around. So, essentially, they just added a fuzzy layer between the mechanical setup and the throttle... I have to agree with you then that a non-DBW TB would be more responsive...

 

From Acura Style, issue Summer 2006:

"Putting the pedal to the metal in the latest Acura vehicles is not exactly what it used to be. The metal is history at least, metal in the form of the cable conventionally used as a mechanical linkage beetween the throttle pedal and engine.

In its place, an advanced Drive-By-Wire (DBW) Throttle System now sends the message electronically from your right foot to the engin compartment. Based on technology originally developed for the NSX, Acura's iconic supercar, the computerized system uses sensors to read pedal angle, throttle position, road speed, engin speed, and transmission gear position. It constantly monitors this information for optimum performance, drivability, and efficiency.

The system does more than act as an electronic "go" pedal. It coordinates engine management with the Sequential SportShift automatice transmission and Vehicle Stability Assist (VSA). Drive-By-Wire allows throttle response to be more precisely tailored to suit driving conditions. When you are crawling along in city traffic, for example, as you step on the gas pedal, the throttle is programmed to respond in a smooth and progressive manner, to minimize the bobble-head factor of stop-and-go driving. During high speed driving, the throttle opens with a much sharper response, as required for quick acceleration during passing situations. In snowy or icy conditions, when maintaining traction requires a lighter touch on the accelerator pedal, the Drive-By-Wire system assists the driver by modulating throttle response along with quicker and smoother activation of VSA. Drive-By-Wire also allows for smoother transmission shifting, especially when driving up or down hills.

With the advanced DBW system, Acura engineers have turned the phrase "putting the pedal to the metal" on its head. Instead, they put high-tech mettle into the gas pedal so when it's time to step on the throttle, Acura owners can boast that they've got it wired."

I think that acura spend a lot of time on it thou, even thou the DBW system is not as good as some other company (like BMW and etc.), we should be proud of it!!!

 

i totally disagree with this. dbw causes more bobbing, especially from a dig, unless you super baby it, which is what i do to make it smoother for passengers

 

It's funny how the article describes some of the very issues with the DBW throttle and touts them as advantages. The change in throttle response based on vehicle speed is something that catches savvy drivers off guard--makes the car feel unpredictable and thus difficult to get used to (how many times have we heard that here )

Note that this exact concept is applied to the Airbus A300 series passenger jets (which are all fly-by-wire)... For example, the rudder pedals respond differently based on the speed of the aircraft. Back in November 2001, a pilot was not aware of this "feature" and his actions (a result of his training and experience as a pilot) caused the vertical stabilizer on an A300 to sheer off due to insurmountable aerodynamic stress--resulting in a horrific crash in the middle of a neighborhood in NY.

By no means am I saying that Honda's DBW system is destined to cause terrible loss of life, but this is just an example of how added complexity and alleged "convenience" features often make life more difficult and aggravating. I'm sure these ideas looked absolutely splendid on paper, but so did New Coke. In practice, they all suck. Engineers should focus on more important things like, oh I don't know, getting rid of the abrupt step in power that VTEC produces... You know, practical stuff.