Drive-by-wire Throttles

Setec Astronomy · 02-17-05, 08:30

I understand the 2005 GM 3800 Series III engines (or at least certain applications) utilize a drive-by-wire throttle. I know that Accumulator has had at least one bad Audi d-b-w experience; anybody have any experience with GM's implementation? Supposedly they reduce the gain at low speeds to "aid in parking", and increase it at high speed.

Shiny Lil Detlr · 02-17-05, 08:34

The 4200 I6 in my Envoy is drive-by-wire, I've had no problems at all with it, response is just as good if not better than a cable system like I had on the 4.3L V6 in my old Blazer

TW85 HHI · 02-17-05, 09:00

http://www.post-gazette.com/pg/05036/453222.stm

I know the article focuses on Toyota and Lexus but further into the article it mentions other vehicles having the same issue. My car has throttle and/or transmission hesitation at times.

Quote:

The hesitation problems have been reported by owners of Lexus ES330 models made between 2002 and 2004 the Toyota Camry and Highlander and other Toyota and upscale Lexus brand models equipped with the same five-speed automatics.

A search of NHTSA records and interviews with Consumer Reports magazine also show owners of other car makes are suffering from the same hesitation problem, including BMW's 3 Series, Ford Explorers and Escapes, and Dodge Durango 4x4.

David Champion, senior director of Consumer Reports' Auto Test Center in Connecticut, said the magazine's testers have encountered the same problems in the Audi A6 2.7T, the Audi Allroad, the Mazda6 equipped with the V-6 engine, and the Volkswagen Jetta 1.8T.

Spokespersons for those companies could not be reached for comment.

What makes the issue perplexing is that no two models of a given car brand may have the same problem. Some owners of the makes involved say they've noticed nothing, while others will say the problem is chronic.

One Lexus dealer, for instance, has said he was able to duplicate the problem only on a few of the cars on his lot, while many others didn't have the problem at all.

The problem involves the transmission gearbox electronic control unit and the engine management control unit, Champion said.

"It's the way in which the transmission gearbox electronic control unit talks to the engine management control unit. The integration of the two systems will allow the transmission to function in the right gear and the engine to provide the power instantaneously in a smooth fashion," he said.

"When you accelerate, the gearbox may change down a gear or find the right gear, and to make the transmission takeoff a smooth one, it retards the ignition to reduce engine power. Unfortunately, while the control unit works out what it's supposed to be doing, you're putting your foot on the accelerator. It can lose its way and doesn't energize the engine and transmission quickly enough," he said.

Setec Astronomy · 02-17-05, 09:06

TW85, that doesn't really say anything about the drive-by-wire throttles. Which means that the gas pedal isn't connected to the throttle butterfly, it's connected to a potentiometer, which tells the computer how far your into the gas, then the computer decides what you mean by that, and if it's the right thing, and how much you really *meant* to push it, and rotates the butterfly by itself. Better not make any jokes it doesn't like.

TW85 HHI · 02-17-05, 09:13

I know what drive-by-wire is and it is mentioned in the article. One problem is it is meant to be more efficient and to do so, it doesn't instantly respond to every depress of the gas pedal (though theoretically it should be at least as responsive). Real world experience is usually different.

Read closer.

Setec Astronomy · 02-17-05, 09:26

Quote:

Originally posted by TW85 HHI
I know what drive-by-wire is and it is mentioned in the article. One problem is it is meant to be more efficient and to do so, it doesn't instantly respond to every depress of the gas pedal (though theoretically it should be at least as responsive). Real world experience is usually different.

Read closer.

I only read your quote, which doesn't mention that (I don't think). I am looking specifically for feedback on the GM implementation.

GoodnClean · 02-17-05, 10:42

These DBW throttles are a PIMA, all I get done is listen to people whine about them on the LOC board...

Guess My Name · 02-18-05, 08:14

GM has been using them for quite a while as well as other manufacturers.....my 2002 avy has it....

Purpose is for more fuel efficient engines and better performance...

the pedal sends a signal to the computer and this signal is different depending on engine manufacturer engine computer....

most rely on a 0-5 VDC signal from pedal and the usuable range is from .5 volt to 4.8 volts...anything outside this triggers the check engine light....

some other manufactiuurers utulize:
PWM signal
Double PWM signal
double voltage signal
Idle speed switches
WOT switches
etc etc etc

I am pretty sure you would be hard pressed to find a new car manufactured today that does not have an electronic throttle

From my understanding of discussions with GM engineers is it allows them to do more things and also control the tranmissions a bit better.....ease of assembly....etc etc...

PS....I sell the pedals to the industrial market for use on forktrucks and other mobile equipment....

I bet in a few years you have brake by wire.....

blkZ28Conv · 02-18-05, 08:27

I believe all C5 and C6 are DBW. I have driven several C5's and really never notice any difference to the point where I thought about this system after driving vehicles. In other words I always kicked myself for not closely analysizing the DBW when driving these vehicle to see if this old guy could detect any difference.

Axe · 02-18-05, 08:32

There is a definate lag in my cars implementation of DBW, and it takes some getting used to. I much preferred the older method, with the cable pulling the throttle butterfly it felt more responsive, more immediate.

I know its not directly related to the GM, but I reckon it is something you have to live with in today's modern cars?

Macgirl · 02-18-05, 08:52

Quote:

Originally posted by Axe
There is a definate lag in my cars implementation of DBW, and it takes some getting used to. I much preferred the older method, with the cable pulling the throttle butterfly it felt more responsive, more immediate.

I know its not directly related to the GM, but I reckon it is something you have to live with in today's modern cars?

These are my exact thoughts also. My Passat has DBW and it is different. Sometimes it really drives me crazy, like if you go to pass a car and gun it to pull into the lane and then by the time the gas catches up to your foot you are back to easing off the gas but the torque jerks you forward like a slingshot. Sorry this isn't GM related.

DavidB · 02-18-05, 08:53

I have zero complaints on the responsiveness of my Porsche Cayenne S. The response on the transmission and throttle are very smooth and "connected". I could not imagine going back at this point. Even the ignition, which is an electronic system, works better and is very smooth. The days of grinding the starter and starting accidents are over.

I took the Cayenne out in the mud the other day (at a high rate of speed!) and when I got back on the road the machine was smart enough to unlock the axels.

I have switched PSM (stability management) off on wet roads and the vehicle is all over the road. Switch it on and you'd never know the road was wet. This would not be possible if not for the DBW systems.

I'm sold and love DBW.