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Double Bimmers
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CD-55 said:
Yes I also like my Drive By Wire logic very much.

The one and ONLY odd thing is does it is when your foot is off the gas pedal then you stomp on it... there is a short (1/2 sec) delay before it really goes for full power. My guess is this is a stupidity check to keep people from ramming into their garage wall. It is like the computer says… full throttle…. Are you sure… well OK you got it.

EDIT: WHEN MY 330Ci...Compared to the E36 and E46 M3 the engine is just not able to rev as quickly. I do not think it's slower rev speed is the fault of drive by wire, I think it has to do with mechanical differences. Maybe it is nothing more than a heavier fly-wheel?

Once you are on the gas and driving like at an autox cross I find the E46 DBW system to be very precise and satisfactory to my needs. Honestly no complaints at all for competition use.
 

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Actually that short delay is due to the design of the feedback loop system. I am sure the BMW engineers are aware of that. There is always a way to diminish this delay but never totally eliminate. DBW is after all a mechantronic system.

There is a commonly known "waterbed effect" in the controls engineering world. Here's the situation, I want to decrease error (by attaining a desired goal) and suppress noise (here noise does not necessarily implies fuzzy audio quality, but includes all unwanted frequencies). Or in layman terms, when I stomp on the accelerator, I want an immediate response. However it turns out that the more you suppress noise the larger error you will encounter. This simply translates if you want an immediate response, expect a huge error. This is similar to sitting on one side the waterbed and observing a hump on the other side.

I have TA a couple of courses in feedback control systems and taught this waterbed effect a number of times. Strange but true phenomenon in controls engineering. It's happening in the DBW system too.

On the other hand, since mechanical throttle linkages are rigid bodies, there will be more of the so called "feel" and "responsiveness". But more mechanical parts means higher maintainance in the long run and more fatigue on the linkages. Delphi Automotive already have developed the DBW brake systems. Believe me, I love mechanism design. But wires are the way to the future.
 

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I like cookies.
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Discussion Starter · #24 ·
in_d_haus said:
I like the DBW overall and think it's the wave of the future. It is not perfect but I'm sure it will just get better.

I drove a friends '97 M3 and hated how heavy the throttle was.
I agree, it is not perfect. But, I think it is better. The lighter throttle makes driving, especially enthusiast driving and heel-toe downshifting easier. Also, it is good for DSC and SMG.

What did you have before the 325Ci?
 
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nate328Ci said:


I agree, it is not perfect. But, I think it is better. The lighter throttle makes driving, especially enthusiast driving and heel-toe downshifting easier. Also, it is good for DSC and SMG.
You boggle my mind. The damn thing won't blip, so how in the world can it make heel-toe EASIER? That defies reason. And it's quite the opposite of the truth.

But having the three of four DBW defenders as the only guys contributing to this thread keeps this from being in any way a balanced discussion.

So I'm out...
 

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Discussion Starter · #26 ·
TD said:


You boggle my mind. The damn thing won't blip, so how in the world can it make heel-toe EASIER? That defies reason. And it's quite the opposite of the truth.

But having the three of four DBW defenders as the only guys contributing to this thread keeps this from being in any way a balanced discussion.

So I'm out...
It does, and is very easy to blip :)

I think this particular 330 was an Oct. 00 build :D

We have several enthusasts here that agree and my observations back to back yesterday tell me that the DBW is much easier to rev-match :)
 

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Double Bimmers
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TD said:
You boggle my mind. The damn thing won't blip, so how in the world can it make heel-toe EASIER? That defies reason. And it's quite the opposite of the truth.
I will give ya that point... The M-cars rev faster which should make heal-toe eaiser, but I can still manage to heal-toe fine with my DBW car, but your M would be even eaiser.
 

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In addition to easier and better integration of functions like DSC, cruise contolr and ABS, lower maintenance, easier assembly (and makes left and right hand drive variants easier to implement) The new Valvetronic engines absolutely require DBW because there is not throttle body plate that can just be opened and closed-- the valve lift has to be adjusted mechanically and controlled via a computer. As another poster said, I'm sure BMW wants to reduce the number of component they use as much as possible-- and they've probably designed their DBW modules to "plug and play" with either the normal throttle bodies in the 6 cylinders or the valvetronic controller in the 4 cylinder models (maybe the same controller is even also used on the valvetronic 8).

I don't like the plasticky sticky feel of the BMW's current implementation of the "pedal simulator" module-- but don't forget-- the system used in the 99 and 00 was not reallly a pure mechanical system either. You were actuating a linkage, but the linkage was connected to an electronically controlled throttle body which controlled a motorized throttle butterfly. Basically you were pulling on a long wire that was connected to a spring loaded actuator. The feel "seemed" better you but you were no more "connected" to the throttle. Although I guess this older system probably transmitted vibrations from the engine compartment. THe e36 may have even used a similar system but i'm not sure (i bet it did). I bet if BMW put their minds to it they could make the new pedal simulator feel just as good as the old one. Unfortunately, they seemed to just totally cheap out and made a pedal that feels like it belongs to a cheap video game system. I'm hoping that the revised "non sticky" pedal that's available now will be a step in the right direction.
 

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Double Bimmers
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nate328Ci said:


It does, and is very easy to blip :)

I think this particular 330 was an Oct. 00 build :D

We have several enthusasts here that agree and my observations back to back yesterday tell me that the DBW is much easier to rev-match :)
Mine is also an 00 Oct build... It is very good, but I think the M3 (E46 and E36) are even better because the rev faster and without the slightest delay.
 

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I like cookies.
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Discussion Starter · #30 ·
CD-55 said:


Mine is also an 00 Oct build... It is very good, but I think the M3 (E46 and E36) are even better because the rev faster and without the slightest delay.
I really can't understand why people hate DBW. The only thing that it lacks over earlier models is a heavy, mechanical feel. That's it really, from my experience. It responds more quickly, is lighter, and easier to drive and rev-match.

The M cars are mechanically more responsive than non-Ms, the E46 M3 has 6 different throttles :bigpimp:
 
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nate328Ci said:


I really can't understand why people hate DBW. The only thing that it lacks over earlier models is a heavy, mechanical feel. That's it really, from my experience. It responds more quickly, is lighter, and easier to drive and rev-match.

The M cars are mechanically more responsive than non-Ms, the E46 M3 has 6 different throttles :bigpimp:
Driving them back-to-back, my wife's E36 323iC had significantly better (faster) throttle response than my 330i. Period. And it just (unquantifiably) FELT BETTER.

Period.

I'm out again...
 

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TD said:


Driving them back-to-back, my wife's E36 323iC had significantly better (faster) throttle response than my 330i. Period. And it just (unquantifiably) FELT BETTER.

Period.

I'm out again...
It's what you are used to TD. I'm guessing you are so used to the mechanical throttles that you didn't give the DBW and credit. OR maybe your car had a defect?
 

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superwagon pilot
'17 991.2C, '19 e450 wagon, 11 135iC, 09 x3
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TD said:


Although I suspect he may need treatment soon as he's obviously hitting the LSD pretty hard.
I think it is the lack of an LSD that is Nate's real problem. :D

As for the DBW throttle, I think it's low on the list of things that make the E46 less fun than an E36. The clutch feel on the otherhand :banghead: I still f up a shift or two everytime I drive the damn car. It's so frustrating since I've driven manual tranny cars since my Drivers Ed days and I've never before had any problems with smoothness and crisp shifting in manuals :dunno:

I noticed the E46's extra weight the other day when I was driving spiritedly on some very hilly roads as well. I very much noticed the extra inertia being carried by the car as I crested the hill, and the car lifted off the pavement unsettlingly compared to the old E36...

ACK said:

Can the DBW cause a mild "rocking" feeling when accelerating in first gear? I notice this happens sometimes with my car. I shift, step on the gas and the car feels like it rocking or jerky up until I take my foot off the gas and re-apply it.
I do this too on ocassion. Not sure what causes it, but I think it occurs because you launch at too low an RPM and when you floor it the engine doesn't have the torque to rev up as quickly as the inputted fuel flow (toally pulled that out of my ass...)
 

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Rest in peace, Coach
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I'd have to say, eventhough I don't HATE the drive by wire on the 330/325s I like my semi-mechanical throttle so much better. It's something I think I can learn to live with, but the drive by wire throttle has too much free play in it, too light, and feels "digital"...there are definate "steps" in the throttle that makes it harder to modulate.

That was the first thing I noticed when I drove my friend's E46 M3. No lag, but there are these subtle little steps that the throttle wants to settle into. Very annoying at first. Same thing on the track when I was driving Raffi's 330Ci, there's that initial lightness and then all of a sudden it's got more resistence. My instructor had to CONSTANTLY remind me not to mash the pedals and be smooth.

It all comes down to how well and how quickly you get adjusted to it. It took me a few hours to adjust to my friend's E46 M3's pedal but I think I can live with it.

Again, I would still prefer the semi-mechanical design of the older E46es. And if we're not given a choice (all new BMWs will be on DBW, mark my words) I think I won't have a problem with it like TD.

But that lag is definatly programmable. There is no such lag in the M3.
 

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wont the shark injector solve some of this as it (in addition to all the other things it does) helps throttle response? i'm not positive as i refuse to do research on the shark injector until i know when it will be released for the 325/330 cars, but from what i've read in the past the SI increases throttle response, which i'd assume reduces or eliminates the delay?
 
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