The Forte had a horrific throttle reponse. After getting it tuned it was soooooo good.
The Forte had a horrific throttle reponse. After getting it tuned it was soooooo good.
Come. Drink the kool aid.
Maybe they've gotten better in the last 10 years, but every mid 2000s car with a manual and dbw was pretty bad for shifting. Probably the worst was an 07 Aston Martin v8 vantage! That was pretty tricky to get a nice shift.
Throttle by wire has come a LONG way in a short period of time, and some manufacturers do it better than others. For example: My 2009 WRX was stupid and laggy with pedal inputs. It would also rev-hang as part of its programming, which was beyond annoying. My 2012 Mazda 3, on the other hand, is an absolute pleasure to modulate throttle with. It feels responsive and has zero rev-hang.
My '07 Scion tC often treats my throttle inputs like suggestions. It's laggy and I've adjusted somewhat but heel-and-toe is still elusive. I've changed the timing of regular double-clutch downshifts which helps but I haven't got the hang of heel-and-toeing this car yet.
In an automatic transmission car, I suspect it would be pretty hard to tell if it's DBW. I haven't driven a great spectrum of first generation DBW cars, but I've never noticed an issue. I can report the RX-8's throttle responses nicely.
My 2000 S70 with the Magneti Marelli throttle isn't so bad. My father's 2010 Sentra is almost impossible to shift properly, there is almost a second of delay between your foot and the throttle.
In reply to Run_Away :
fully aware, but it was an auto appliance, that actually worked pretty well.
Keith Tanner said:...Instead of measuring the air going into the engine and adjusting the fuel/timing parameters to suit with a little bit of lag, the ECU knows how much air is coming the instant the accelerator pedal is depressed so that the engine can be ready when it arrives.
Would you elaborate more on this? I don't have the level of familiarity with modern cars to quite grasp the difference between the two scenarios.
It's advance knowledge for the ECU.
Drive by cable: You press on the throttle pedal. The butterfly opens. The engine gulps more air. The ECU measures that air and provides the appropriate fuel and spark, or maybe does something with a turbo. But it can't do anything until the extra air is measured, which means there's a slight lag. You can work around this to some extent by monitoring the throttle pedal and extrapolating what's going to happen, but it's reactive by nature. The ECU has no control over how much air is going into the engine.
Drive by wire: You press on the accelerator. The ECU immediately knows that you are requesting more torque and then proceeds to make it for you. It could be with timing, it could be with more air. Regardless, the ECU knows what you're asking for and has full control over how to make it happen. It can even open the butterfly wide then back it off again. The point is that it's actively responding to your request and has full control over what happens when.
In reply to Keith Tanner :
Actually, the fuel and spark reactions to electronic throttle and cable throttle are exactly the same. There's compensation for transients in both fuel and spark that are estimated, and the strategy hasn't changed since electronic throttle. The air measurement "quickness" is very dependent on how it's measured- MAF or MAP. And both of those also have transient compensation that hasn't really changed due to ETC.
The only thing ETC does is tweak the opening and closing rates to make it feel like *something*. You can over drive it, or you can under drive it- depending on what you want to achieve. Some will underdrive it to intentionally make the driver less aggressive. Some will overdrive it so that it feels more "sporty".
Thanks for the insight, that's how it had been explained to me. I do know that the throttle butterfly and the pedal are uncoupled in the ND Miata, it plays all sorts of fun games that you can see on a vacuum gauge.
A coworker installed the stock GM throttle map on my Miata as part of a tune update. It's very slow on initial tip in, then more aggressive as you get closer to 100%. Probably to make it easier to modulate the power for a clunky driver. I didn't even make it out of the parking lot before telling him "something's wrong, I've lost all my throttle response". Reloaded the completely linear map, the engine felt SO much better.
I don't notice/feel any difference from the cable on my ZX2SR to the dbw on my Fiesta.
I don't even know which the KJ had. Never saw a reason to check.
Keith Tanner said:Thanks for the insight, that's how it had been explained to me. I do know that the throttle butterfly and the pedal are uncoupled in the ND Miata, it plays all sorts of fun games that you can see on a vacuum gauge.
A coworker installed the stock GM throttle map on my Miata as part of a tune update. It's very slow on initial tip in, then more aggressive as you get closer to 100%. Probably to make it easier to modulate the power for a clunky driver. I didn't even make it out of the parking lot before telling him "something's wrong, I've lost all my throttle response". Reloaded the completely linear map, the engine felt SO much better.
This is part of what drives me nuts about DBW; the cable-actuated throttle body is deemed obsolete and inefficient and is replaced by one that is actuated by a servo. Then, if the DBW system doesn't respond properly to throttle inputs, people can shell out some extra cash for a tune to make the servo-driven throttle body behave more like the component it replaced.
The DBW throttle body is obviously more easily integrated into the other electronic engine controls and due to that fact, it has the potential to return better efficiency since it can be programmed to seemingly ignore input from the driver and do what is deemed to return the best efficiency. It can be very well done in some high-end vehicles (E39 M5), but at my price point, it's more likely to be done poorly so I was hoping to avoid it while still buying new.
Cable driven throttles aren't necessarily linear either. Put a cam on the throttle shaft and voila, you have a non-linear throttle plate response. GM was notorious about doing this, making the initial tip-in very aggressive to make the car feel more powerful. If you didn't like it, you could buy a different wheel for the shaft. Exactly the same thing you don't like about DBW.
Stop getting wound up about it. Drive the car and make your choice on how the car works. Doesn't matter how it gets there, what matters is the end result.
The RX8 I had used DBW. The only complaint I had about it was one time when the battery was dying, still had enough juice to start the engine just not enough to operate ancillaries. Like throttle. It would just sit there and idle, pressing the go-pedal did nothing. Like it wasn't hooked up. Replaced battery and everything worked again. Thinking about it, it was probably a good thing it did that. Wouldn't let you go anyplace with the dying battery that could leave you stranded someplace.
Keith Tanner said:Cable driven throttles aren't necessarily linear either. Put a cam on the throttle shaft and voila, you have a non-linear throttle plate response. GM was notorious about doing this, making the initial tip-in very aggressive to make the car feel more powerful. If you didn't like it, you could buy a different wheel for the shaft. Exactly the same thing you don't like about DBW.
Stop getting wound up about it. Drive the car and make your choice on how the car works. Doesn't matter how it gets there, what matters is the end result.
I was going to point this up as well. Throttle body and carb throttle pedal cams used to be a thing.. no body is perfect.
I guess they still are.. https://www.only944.com/partscatalog/only/throttleresponsecam/
In reply to Keith Tanner :
I would postulate the drive-by-cable ECU knows something's coming as soon as the TPC measures the throttle opening voltage. It already knows the engine rpm and the temperature.
jj said:I can only speak from my own experience, but every single DBW car I have driven, even sporty manual ones, have had a slight delay between foot and action. To me this is not acceptable. When it comes to throttle response, I'll take my 90's cable cars.
How recent were they and are you sure you weren't experiencing engine shutoff aka fuel save mode?
Jerry From LA said:In reply to Keith Tanner :
I would postulate the drive-by-cable ECU knows something's coming as soon as the TPC measures the throttle opening voltage. It already knows the engine rpm and the temperature.
I will confirm that they do. Just like for cable systems. Especially since it really matters what the actual throttle does for airflow rather than what it should be doing.
In reply to jj :
I disagree, at least on my Fiesta. The very slightest pedal movement makes a change.
I had to adjust the cable on my ZX2SR to get anything close. Too much slack at the TB.
My GMC is DBW and I can not tell the difference. In fact I thought it was a cable when I got it as it has the 6l motor in it.
In reply to Keith Tanner :
Betty is the Same way. She is more towards the stock side. I like it now as I'll blow the tires off her in first gear all of the time. Long term though that'll have to change. God forbid she sometimes feels slow. Nothing some 275 rubber on all corners won't fix.
I'm pretty sure the 2005 S2000 was one of the last cable driven throttle body cars produced.
A lot of great insight in this thread about the DBW systems.
I've really only got two complaints about DBW systems and in some vehicles it's like you have to double tap the gas pedal for the ECU to realize you're wanting more power. It's like hitting the turbo boost button on an old N64 game.
The second is in some manual cars; typically non performance vehicles, during a power shift or a down shift it's almost impossible to get the revs to match. Some of it has to due to ECU tuning and rev hang but it's just like "okay then."
In reply to jj :
Wow, you must be really sensitive when you can feel tenths.
When I mentioned the slight movement, the tach needle jumps at the same time. No delay noticed.
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