General > General Technical Chat

Throttle Controllers

<< < (3/8) > >>

@rt:
This is the wall of text I see most often on one of the Facebook adds.
I have a 4WD, and look at 4WD stuff, so that’s probably why it keeps being shown to me.


.....

WHAT IS THROTTLE LAG?
Well first we have to take you back to the good old days of throttle cables and carburetors. In the old days, the gas pedal was directly connected to the engines throttle plate by a cable, and any lack of response from the engine could be attributed to a couple of things. Either the cable has stretched enough to create slack and, consequently, a delay in pedal response, or the engine was out of tune which meant it was not making as much power as it should've been. Easy fix, buy a new throttle cable for $20 and get your carby tuned. Nowadays though it's not that simple.
Let's look at how electronic throttles work. Instead of a cable, the pedal is now connected to what essentially are potentiometers. They generate a certain amount of voltage which the ECU reads and equates to throttle angle openings. They first of all measure how far your foot travels when you push the pedal to a certain point as well as how fast you pushed the pedal to reach that point. The ECU then sends a signal to the butterfly position sensor which controls the opening rate of your butterfly on the throttle body, and opens it up by the amount programmed into the ECU for a given voltage generated at the pedal. There is also a feedback sensor on the throttle body which informs the ECU that the throttle butterfly is doing what it is supposed to (i.e. opening the throttle up to the angle dictated by the ECU).
Now, like with most electronic control systems, there is redundancy built into drive by wire systems. Instead of just one demand sensor at the pedal, there are two. Same goes with the feedback sensor at the throttle body. This is to avoid loss of control should one fail. The complex nature of this system with its variety of potentiometers, computers, sensors and management systems is what results in a noticeable delay when you first hit the pedal, known as throttle lag or dead zone. No matter how hard or fast you stomp on your accelerator there is no overcoming this delay, it is an inherent electrical delay that physical input cannot overcome.
Why the change from a physical cable to invisible electrons telling your engine what you want to do? Well a few reasons, first of all the electronic throttle system is a lot lighter, reducing weight in modern cars, also they are far easier to service and tune, simply hook up a computer and let it do the work for you. It is also worth mentioning the impact of emissions control in regard to switching to electronic throttle systems, using electronics allows for much more precise control of the throttle opening compared to a cable that stretches over time. It also allows the throttle response to be programmed in by the manufacturers. Yup, that's right. The throttle response on drive-by-wire control systems can be programmed. This is where the EVC Throttle Controller comes in.
The EVC Throttle Controller modifies the voltage signal from the drive-by-wire pedal assembly to allow you to tune the response from your accelerator pedal and greatly reduce the dead zone from when you initially depress the pedal, commonly referred to as throttle lag. The EVC does this by providing new points of reference for the vehicle's throttle mapping. It is still working within the standard parameters; however, it introduces a far sharper throttle curve. It is also actuating the throttle earlier in the pedal stroke, introducing petrol and air into your engine earlier in the throttle stroke thus improving throttle response and performance.
The real benefit of the EVC though is its ability to give you complete control over the throttle response of your vehicle, if your vehicle is too responsive you can dampen its response to a level that suits your driving style. You can also change the EVC's settings and modes on the fly so if you are driving along the freeway and need to overtake someone, crank the iDRIVE up a few levels to deliver better throttle response, or if you are towing a trailer/ caravan you can bump up the throttle settings to account for the extra added weight. Don't just take our word for it though, every EVC comes with a 30-day money back guarantee so you can try the EVC and see its effectiveness for yourself.
Check it out for yourself:

AndyC_772:
This:


--- Quote ---The complex nature of this system with its variety of potentiometers, computers, sensors and management systems is what results in a noticeable delay when you first hit the pedal, known as throttle lag or dead zone.
--- End quote ---

...is simply untrue.

If there's a lag when you increase pressure on the accelerator, it's because the car's ECU has been programmed to keep the engine running closed-loop whenever possible. Closed-loop means the fuel/air ratio is controlled, making use of the lambda sensor, to maintain the ideal mix for complete combustion.

Small increases in power can be accommodated this way, but a rapid or major increase in power output requires running the engine in open-loop mode. The amount of fuel is increased, the fuel/air ratio increases, the engine produces more power, and hydrocarbon emissions go up. Thus, for emissions reasons, the ECU is programmed to avoid doing this unless it's definitely required.

Any resulting delay in throttle response is not due to "the complex nature of this system"; it's a side effect of this deliberate feature of the ECU.

That doesn't mean a delay when you actually do call for more power is desirable, though.

A device that essentially remaps the position of the throttle pedal can't overcome pure delays that exist in the ECU's programming, but it might mean that a relatively small increase in pedal travel is enough to exceed a programmed threshold for what constitutes a 'small' throttle opening vs a 'large' one.

It's not doing anything you couldn't do just by pressing harder on the pedal, but if it means the overall system response matches the driver's preference or expectation, it's no 'worse' than having a seat that slides forwards and backwards to make the reach to the pedals more comfortable.

SilverSolder:

There isn't anything wrong with re-tuning the "feel" of the throttle pedal, it is no different than customizing anything else on your ride...

I sometimes drive a friend's muscle car, which uses an electronically controlled throttle.  Let's just say that throttle response is not as much of an issue as making the rear tires last for longer than 20 miles or so!  :D

David Hess:

--- Quote from: @rt on March 30, 2021, 05:45:48 pm ---Modern cars feature fly by wire, and their accelerator pedals contain a spring, and a sensor that is just a variable resistor.
--- End quote ---

The ones I have studied use a reversed redundant pair of hall-effect sensors and not any sort of resistive element.  Personally I think this is still reckless because of additional failure modes compared to reversed redundant pair of LVDTs or RVDTs with AC excitation and synchronous detection.

james_s:

--- Quote from: SilverSolder on April 01, 2021, 02:26:42 am ---Applications engineers that work on the engine management systems of modern cars spend a LOT of time getting the "feel" of the accelerator "just so".  This is mostly done by testing on the track and on the road...  after all, only a human driver can tell you how the accelerator "feels".

And the "feel" that they aim for will be different depending on the target market.   The electronic throttle in a Mustang GT will not have the same goals for throttle response as a Toyota Camry!  :D

--- End quote ---

They did that on old cars too. I remember discussing this a while back with a friend, he was talking about a car someone he knew had in the 80s that had a really aggressively tuned throttle, it was done so that if you just touched the gas from a stop it would feel powerful, puttering around town it gave that feeling of "whoa, this thing really wants to go!" but then if you actually stomp on it, it would pretty much run out of steam. It was not a very powerful car, it was just tuned to create the illusion of being powerful.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod