Drive by wire, technology driving us backward

[01rangerxl]

I am sure this technology has its place, but I think manufacturers are doing a very poor job as far as tuning.

I have heard numerous complaints of hesitation, poor acceleration, and other drivability issues with these systems. One guy on another forum I visit has a 2007 GMC Sierra with the high HP Vortec Max, and while he loves the truck overall, his big complaint is the drive by wire. He says the truck hesitates when he needs to pass.

Sorry, but for the time being, I would prefer to have a cable that responds to me directly. I don't need a computer saying "nope, can't do that" or "give me a sec." Just give me a cable until all the bugs and drivability issues that people seem to have with DBW are resolved.

 

[firemachine69]

For the Sierra dude, it's an internal design made so if you accidentally mash the gas for a split second, you don't light up the tires and lose control on a slippery surface.

There are plenty of plug-and-play solutions for your friend. Plenty.


I agree however, I much prefer the throttle cable. However manufacturers love that they can program a non-linear power curve to aid in emissions reduction and fuel consumption.

 

[astraelraen]

There is some complaint of the newer Mazda's, especially the MZR turbo model and DBW hestitation. That or the computer closing the throttle at upper RPMS.

I think the problem comes when the manufacturer programs the vehicle to not give you what you are asking for. That seems like a dangerous proposition. If I press the pedal down 100%, I expect 100% throttle. To give me less seems like a lawsuit waiting to happen.

There are positives that have been mentioned though, better emissions performance. Also DBW throttle lends to EASY traction control. Simply close the throttle plate, viola, cheap to produce.

 

[Papa Bear]

TBW makes it easy to add cruise control if you don't have it from the factory ...

Also makes it easier for On-Star to cut my throttle back on request by the cops.

 

[Max_Wander]

Originally Posted By: astraelraen
There is some complaint of the newer Mazda's, especially the MZR turbo model and DBW hestitation. That or the computer closing the throttle at upper RPMS.


That's been a major problem IMO with the DISI Turbos, I've seen logs where by 6000rpm, the ECU pulls the throttle back to only 30%!! This is why most dynos always show the full 280ft/lbs of torque but the max HP varies wildly depending on the test conditions (heat soak, IC outlet temp etc). When I have the pedal to the floor, I expect 100% throttle! My friend has complained about 1 full second intervals of total hesitation in his Saturn Vue with DBW, noisy potentiometers I estimate. I cleaned his potentiometers and that solved the problem.....for about 5 months now the problem is back. Pops had a 91 BMW 750iL that had the right bank DBW servo completely fried. Back in the 90s replacements were not cheap. If I were to buy a DBW car, I'd probably convert to cable actuation or gut the radio controlled, nanny-control ECU's out for a programmable stand alone.

 

[Junior]

I think it all comes down to the money. 100 million dollar fighter jets are all fly by wire. 20,000 dollar car probably not the same caliber but I still like it.

 

[JTK]

Originally Posted By: Papa Bear

Also makes it easier for On-Star to cut my throttle back on request by the cops.

Yessir and it does reduce *some* chance of any funny business. My 2005 Trailblazer had the most software driven TBW I've ever owned or driven. The engine would not rev passed 2K in park or between gear selections. If you fluttered the go-pedal, it would filter it out. My Cobalt isn't quite so buffered, nor is my new Odyssey. That thing will go where ever you put it, in any state.

Joel

 

[rationull]

Originally Posted By: JTK
The engine would not rev passed 2K in park or between gear selections.



Just to be pedantic, you don't need DBW to do that. All you need is fuel injection with an ECU that knows what gear you're in.

 

[ekpolk]

FWIW, I hated the DBW in my 2003.5 V-6 Camry. Clearly, the programmers had injected too much concern for maximizing fuel economy, and failed to program in enough respect for what the driver actually wanted at the moment. By contrast, my Prius also has DBW, but the way it's programmed does not make it obtrusive like the system from the Camry. Personally, I've concluded that DBW has great potential, but if programmed poorly, it can really spoil the overall driving experience.

When I step on the gas, I expect to start going NOW. I don't want a computer delaying execution of my inputs to see if I really mean it or not...

 

[BuickGN]

After listening to a few people on here, I guess I got lucky. I didn't realize manufacturers were programming delays and such.

As for it revving in neutral, it's pretty common for revlimiters to be set lower when the car is out of gear. Now it's done with the DBW which is a little gentler on the motor than the revlimiter.

 

[eljefino]

How about this, at the bottom 20% of the pedal travel, have it mechanically open the throttle, say, 20%. (You can go 65 at 20% throttle). Nice failsafe. Like the WOT choke force-off we had back in the carby days.

My cutlass ciera wagon has a traction control "mystery box" that my throttle and acellerator pedals disappear into. The pedal feel is okay but "raspy" like a bike with a rusty brake cable...

 

[brianl703]

Originally Posted By: ekpolk
FWIW, I hated the DBW in my 2003.5 V-6 Camry. Clearly, the programmers had injected too much concern for maximizing fuel economy, and failed to program in enough respect for what the driver actually wanted at the moment.


I wonder how much of that is due to the vacuum actuator used for DBW on that car.

I think a vacuum actuator would respond more slowly and less consistently than an electromechanical actuator.

 

[BuickGN]

Originally Posted By: eljefino
How about this, at the bottom 20% of the pedal travel, have it mechanically open the throttle, say, 20%. (You can go 65 at 20% throttle). Nice failsafe. Like the WOT choke force-off we had back in the carby days.

My cutlass ciera wagon has a traction control "mystery box" that my throttle and acellerator pedals disappear into. The pedal feel is okay but "raspy" like a bike with a rusty brake cable...


I think someone mentioned in the old thread that toyota does that. The throttle cable goes into a box on the firewall where the sensor is. At WOT, the cable will mechanically open the TB a little.

 

[PandaBear]

TBW make sure the butterfly and the fuel injection is matched at all time, instead of relying the O2 sensor to tell the ECU about over lean condition. This lets engineer design compression as high as 12:1 on 91 gas without worrying about knocking. Taking the safety margin away due to TBW gives you better fuel economy and power, at the expense of complexity and/or throttle response.

 

[rjundi]

Audi has the system right at least in the Audi S4 model. They have a redundant drive by wire sensor and if ones goes out the other takes over and triggers a check engine light. No break downs.

For those cable lovers I did break down on the side of the road in my 88 VW Jetta GLI 16v and my parents 1986 AMC Eagle due to a snapped throttle cable. Maybe terrible bad luck but cables are not infallible like we think.

 

[brianl703]

Originally Posted By: PandaBear
TBW make sure the butterfly and the fuel injection is matched at all time, instead of relying the O2 sensor to tell the ECU about over lean condition.


The O2 sensor is always the final determinant of the air/fuel ratio. TBW has nothing to do with plugged fuel injectors, low fuel pressure, or vacuum leaks, which are the main causes of a lean condition.

TBW vehicles still have MAF or MAP sensors (in fact my Saab 93 has both), because the they are not able to compute the air/fuel ratio (accurately enough) based just on throttle position. (Although some of them will certainly try if the MAF or MAP sensor has failed, but the results are not very good).

 

[swalve]

One thing about all this "newfangled gadetry" is that it makes a vehicle easier to repair and maintain at a like-new state.

Yeah, they are apt to strand you if they go bad. But so will a broken or stuck throttle cable. If you do the math, I'm SURE it's more likely for a throttle cable to fail catastrophically than it is for a throttle by wire system to do so. Even if you do get stranded, the amount of maintenance that these electronic sensors eliminate still makes it a net good. I know I don't enjoy adjusting carb mixture, points and chokes every season change...

And it's a simpler system. With the old way, you have a pedal, a linkage, a cruise linkage, a trans kickdown linkage and a throttle position sensor.

The new way you have a pedal, a wire and a motor. The rest is handled by the computer, and more effectively.

If the engineers do their job, it should perform better too. THe driver uses the pedal to tell the car how fast to go, and the computer decides how best to do that. With the throttle cable, the computer is hamstrung by having the throttle position out of is control.

And finally, it's easier to diagnose and repair. If a sensor goes bad, the computer tells you what the exact problem is. As engineers get better at designing these systems, they can build in better error checking and diagnosis. A good example is the throttle position sensor in non-TBW cars- they set it up so that it ranges from zero to 5 volts. But it's mounted on the throttle such that it only varies from .5 to 4.5 volts. If the computer sees zero or 5 volts, it knows the sensor is shot and tells you so.

 

[DmanWho]

Judging from the "talk" on the SX4 forum, there's a learning curve involved, for those with DBW + the manual tranny.

It seems that there's a RPM hang when the clutch is depressed. Takes some getting used to...

 

[Matt_S]

My '05 Buick minivan has TBW and I have no complaints at all. You really wouldn't know unless you looked under the hood. Responsiveness and power output are fine. The cruise control works fine although I think it's a little too aggressive when accelerating. Stability and traction control work very well, too. The traction control is much more effective than with similarly-equipped cable-throttled vehicles I've driven.

 

[Colt45ws]

With the old way, you have a pedal, a linkage, a cruise linkage, a trans kickdown linkage and a throttle position sensor.
My Vic does not have that. My Cavalier does, but it has a 3T40 which is almost all mechanical controlled, except for the torque converter lockup. You oversimplified the DBW, there is a sensor on the pedal, a computer, and a sensor and a motor on the TB.
Yeah, cables are not infallible, nothing is, but how much did it cost to replace those cables?