Drive-by-wire throttles

[ekpolk]

Originally Posted By: BearZDefect
. . . When they make CVT transmissions without a hydraulic torque converter I'll be excited.


The Prius (and its HSD siblngs, the Camry, Highlander, RX, GS, and LS) is here, and has no hydraulic torque converter, so get excited!

Actually, there is some debate about whether the PGS used in the HSD cars is really a CVT. It is certainly not physically like the the typical belt-chain and cone CVT. All academic debates about nomenclature aside, the HSD cars' trans acts exactly like a CVT, so I'm perfectly comfortable calling it one.

Yes, they do take a bit of getting used to, just because they are something different (not bad in any sense). I find the overall engine-trans response to be very turbine like, except unlike large turbines, there isn't any discernable lag in throttle response. The rpms just smoothly slide up or down seeking the optimum for what you're calling for -- via the accursed DBW throttle.

 

[edhackett]

Ya, but with a cable operated throttle you can tie your shoe laces together, run them under the hood, in the window and get home.

Yes it was an Alfa Romeo.

Ed

 

[XS650]

Originally Posted By: edhackett
Ya, but with a cable operated throttle you can tie your shoe laces together, run them under the hood, in the window and get home.

Yes it was an Alfa Romeo.

Ed


How do you drive with your feet tied together and under the hood?

 

[BearZDefect]

Originally Posted By: ekpolk
Originally Posted By: BearZDefect
. . . When they make CVT transmissions without a hydraulic torque converter I'll be excited.


The Prius (and its HSD siblngs, the Camry, Highlander, RX, GS, and LS) is here, and has no hydraulic torque converter, so get excited!
...

The Prius is definitely interesting. I love the idea of recovering energy during braking. I like a car that is carefully designed for its purpose. (Unlike the siblings you mentioned.)

On the downside I am a bit concerned about the battery, though I'm sure there will be (if not already) good recycling for them soon. I have read the battery discussions. I hope the industry comes up with better batteries soon.

But the final blow to my excitement is I don't have the money to buy one.

 

[Diesel_Clatter]

My ION has DBW and manual transmission. It took much longer to get used to than any other manual transmission car I have ever driven. I don't really notice it any more but for a while I just flat out hated driving the ION. There is just something a little unusual or wierd about how the throttle and clutch work together.

 

[Doug Hillary]

Hi,
"E" throttles have been in use in heavy trucks for over 20years as mentioned earlier by Chris142. Chris is correct in ensuring the moving components of the potentiometer are free in their movement and lubricated as required

By and large they have been incredibly reliable considering the environment they are used in. Many are troublefree for millions of kms (miles too)

In my own experience I know of very few having been replaced amongst the thousand of trucks used by my Clients
I only had one (potentiometer) replaced in one of my trucks - it was a 50/50 Warranty issue as it was faulty (at 700kkms), was out of Warranty and was done "ex gratia".

Porsche moved to an "E" throttle around 1999 and this transformed the drivability of both their rear engined and mid engined cars

Regards
Doug

 

[rationull]

I actually had no idea electronic throttles had been used for so long in trucks. I didn't even know they'd been used before the last few years in cars. I'm pretty much in the same boat as Diesel_Clatter in that it was a little jarring getting used to driving the civic (manual trans). The automatic revving when you hit the clutch (for emissions), and the slight hesitation when you floor it is kind of weird, but not bad once you get used to it. But, I don't really mind it anymore. At some point I want to drive a higher performance car with DBW and see how differently they feel from my civic.

What worries my most is the fact that you can't hack it together to get home if it breaks, like BuickGN and edhackett provided examples of. But it's good to hear that the reliability has been good so far.

Are the throttles used in newer cars engineered to the same level as the ones used in heavy trucks? The biggest problem with the "fighter jets and tanks use DBW" argument is that they cost millions of dollars while cars cost a lot less. Can the same argument apply to the truck comparison?

 

[Kestas]

On average, trucks are built more robustly than cars. I believe this is true for components other than frame and suspension.

 

[ekpolk]

It seems that a certain British Airways crew recently had a very bad experience with the "big brother" version of the DBW that we "enjoy" in our cars. Cables and levers can bind up, for sure, but I'd bet that crew would have liked to have a hard linkage when they realized they had a problem and jammed the throttles trying to fly out of it. Thankfully, after the dust settled, everyone walked away from the incident in one piece. Unfortunately for BA and Lloyds, it looks like that triple-7 may be totaled.

DBW has its advantages, but it's far from a perfect panacea.

 

[mpvue]

Originally Posted By: Diesel_Clatter
My ION has DBW and manual transmission. It took much longer to get used to than any other manual transmission car I have ever driven. I don't really notice it any more but for a while I just flat out hated driving the ION. There is just something a little unusual or wierd about how the throttle and clutch work together.

there is a recent thread on saturnfans about this. the computer 'floats' the throttle between shifts, so the tach stays for a second where it was, instead of dropping immediatly when you take your foor off the gas. the point is to make shifting a manual smoother and easier. in 4 years of driving my 5 speed VUE, I kind of like it, or at least don't think of it. the saturn DBW is very smooth, almost fluid, not at all clunky. power is very linear. the old 3.0 in the saturn L300 was also tuned very well, the throttle felt great. good thing too: the 3.0 was rated at only 181hp, but reports showed it was a good bit higher than that. w/ TC off, an L300 would smoke the wheels all through 1st gear into 2nd.
IMO, electronics have come a long way from chrysler's '70s era lean burn systems. everything in a modern car is controlled by electronics, may as well live with it instead of resisting.
OTOH, I also appreciate well designed elegant mechanicals. on my old '70 nova I used to have, I adapted a mechanical linkage from a chevelle to work; no cable, which I never liked the feel of. connected to my massaged holley carb, anyone that drove that car was amazed at the 'connection' you felt to the throttle. response was immediate, no slop at all. had a manual choke, too

 

[JTK]

Originally Posted By: Kestas
On average, trucks are built more robustly than cars. I believe this is true for components other than frame and suspension.


Exactly, like stated a few times in this thread, it's an apples/oranges comparison between automotive gasoline engine, electronic throttle actuation and what is used for diesel engine injector pump actuation.

Joel

 

[Max_Wander]

My very first experience with DBW was in a BMW 750iL. At 70K one of the two servos failed. If there were only one bank of cylinders, there would be one servo, which would have meant complete failure!

 

[Doug Hillary]

Hi,
Joel - You said:
"Exactly, like stated a few times in this thread, it's an apples/oranges comparison between automotive gasoline engine, electronic throttle actuation and what is used for diesel engine injector pump actuation."

This is not so. The principal similarities are almost absolute. The harsh operating environment (heat,vibration,jarring,dust etc) of the ECM and other components in heavy trucks is in many ways why those units in cars are now so reliable
The first heavy high speed ECM and DBW units were in operation in the very early 1980s on 2 cycle unit injector Detroit Diesel engines

I worked with Bosch, VW and MB on the development of the first (reliable) EFI systems systems in the mid 1960s. I was involved in the prototype cold weather testing in Scandinavia

Regards
Doug

 

[JTK]

Originally Posted By: Doug Hillary

This is not so. The principal similarities are almost absolute. The harsh operating environment (heat,vibration,jarring,dust etc) of the ECM and other components in heavy trucks is in many ways why those units in cars are now so reliable


Doug, I'm with you 100% that the principles are exact. I find it hard to believe component quality is the same though between a $14K Chevy Cobalt and a $200K OTR Tractor.

Joel

 

[Doug Hillary]

Hi,
Joel - Much of what was learned from the early days with ECMs actually mounted on the engine of Heavy Diesel engines has been applied across the board. One thing in particular was waterproofing and the type of elctrical contacts used

Don't always believe that quality is relevant to the purchase price or Brand name - Porsche is but one.................!!

The ACTROS range of Mercedes trucks have had many totally integrated systems (engine-driveline servicing etc) now for many years. My youngest son who is a Tech with MAN (also using highly computerised systems management)confirms that many of the supposed "problems" with these systems are human generated (loose contacts etc) or simply a fundamental lack of practical diagnostic skills!

Regards
Doug

 

[brianl703]

Originally Posted By: mpvue

there is a recent thread on saturnfans about this. the computer 'floats' the throttle between shifts, so the tach stays for a second where it was, instead of dropping immediatly when you take your foor off the gas. the point is to make shifting a manual smoother and easier.


Fuel injected Ford vehicles (probably other makes too) have been doing this for years without using drive-by-wire. They do it by holding the idle air control valve open.

 

[brianl703]

Originally Posted By: Doug Hillary

Joel - Much of what was learned from the early days with ECMs actually mounted on the engine of Heavy Diesel engines has been applied across the board. One thing in particular was waterproofing and the type of elctrical contacts used


ECM that came out of my 1988 Ford Mustang has a silicone comformal coating over the entire board. That ECM didn't fail, by the way, it was replaced for a mass-air ECM as used in newer Mustangs.

 

[brianl703]

Originally Posted By: JTK

Doug, I'm with you 100% that the principles are exact. I find it hard to believe component quality is the same though between a $14K Chevy Cobalt and a $200K OTR Tractor.


The ECM is a tiny cost of either vehicle. It really doesn't cost all that much more to build a better unit.

ECM failures are pretty rare, although in the early days it was common to blame the ECM for problems caused by other components.

 

[Patman]

Originally Posted By: brianl703


The ECM is a tiny cost of either vehicle. It really doesn't cost all that much more to build a better unit.

ECM failures are pretty rare, although in the early days it was common to blame the ECM for problems caused by other components.



The ECM failed on my Corvette a few years ago but it was due to corrosion. The ECM is under the battery, and the OEM batteries have a history of leaking out acid. Plus I think the area that the ECM sits in was not sealed properly from the elements, so road salt got in there. So that failure was not the ECM's fault.

However, 12 hours after getting a new ECM, it died! The tech's said they have never seen that happen ever. This was two years ago and the car hasn't had any problems since.

 

[JTK]

Originally Posted By: brianl703
The ECM is a tiny cost of either vehicle. It really doesn't cost all that much more to build a better unit.

ECM failures are pretty rare, although in the early days it was common to blame the ECM for problems caused by other components.


I don't know if I've ever seen an ECM/PCM be the cause of electronic throttle control issues in a passenger vehicle. ALL the ones I've seen stemmed from the APPS, TPS (which there can be 2 TPSs on the TB) or just plain wiring or connectivity problems. APPSs can take a beating or hold moisture because of where they are mounted and I have seen where the dielectric grease gets funky w/in the potentiometers in the TPSs mounted it the throttle body. Sometimes you can get lucky with a disassembly, cleaning and re-grease if the unit will allow, or just re-seating a connector may be the cure.

Joel