Drive by "electric" wire response

[timfoster405]

I am still having to get used to this drive by wire... which always confuses me since prior to 2005, the accelerator was connected to a "mechanical" wire or cable that gave you direct control of the throttle plate via the accelerator pedel

so everytime I hear "drive by wire" I get confused and have to think a minute..."electric wire" anyway...

Does anyone know if there is a setting embedded within the EEC code that allows for the adjustment of the throttle response... or how fast the throttle plate moves compared to how fast you step on the accelerator pedal. for me, it seems that even though I have a tune from a reputable tuner, the response still seems the same as the stock tune.

I was under the impression that there was an adjustment for this... I have not called my tuner yet... just wondering.

thanks,

 

[69Mach1-409]

I know tuners can adjust it, but you cannot access it through say an Xcal3 or the like.

 

[pieperz06]

i know when i got my tune the throttle response went crazy i had no idea how much it was going to change i think if u cant notice it they didn't change it

 

[07 Boss]

There are 10 points along the throttle curve. A tuner can adjust the response by upping the signal from the throttle position so that the computer thinks it is pressed farther than it really is. This is how the tuner changes the throttle response.
On the mechanical side, there still has to be the physical input of you pressing the gas pedal to move the little actuators in the pedal. Some, not all, due to variances in manufacturing, may have some "play" in their throttle. What I mean is there is a point at which you move the pedal a little bit and the car does not recognize that movement. There was a thread, maybe here or somewhere else, where the guy actually took apart his pedal assembly and made some adjustments to it so that the actual pedal, and the metal contacts inside, were moved closer to the part that detects the movement. After reading this thread I decided that I didn't want to take apart my pedal assembly.
What I did to fix this throttle "lag" was so simple it baffles me that more people haven't done it. All I did was take some double sided foam tape. using only one side of the adhesive, and taped it to the pedal arm where it enters the "little box" where the sensors or actuators are. Basically at idle, the pedal arm contacts the edge of the box that it goes into. I placed a brick on the gas pedal and applied the tape so that at idle it would prevent the pedal from moving all the way up to where it was. I made like a little bump stop between the pedal arm and the box. I actually ended up using 2 pieces of tape to get rid of any play in the throttle. Along with Bama's race tune I have very quick and more precise throttle response with no lag.
If any of you guys don't understand what I am describing here, let me know and I can see if I can get a couple of pics up after I get home.

 

[Wes]

Drive by wire is a pretty complex subject. There is quite a bit of tuning and failsafes built into it.

The short version is that some drive by wire systems use a pedal follower - the electric version of a throttle cable. Press the throttle 75% and the throttle opens 75%.

Ford used a torque-based drive by wire system where we are able to command different amounts of torque based on the load/rpm of the engine.

Think about this - if you want to make a heavy truck "feel" faster you can modify the DBW to give more throttle opening at higher RPMs.

Or how about this - when you go up in higher altitudes you lose power. So why not command more torque at higher altitudes?

The possibilities are endless.

You can imagine this is a bit more complex than a pedal follower but also much more complex and flexible.

Wes

 

[JeremyH]

There is also a physical lag or dead space in the pedal. I did the foam tape mod as mentioned above. There are write-ups on how to bend the brushes so they have a better connection for throttle response. Or to put a spacer to bring the brushes closer to the circuit board.
Here's one such write-up:
http://autobglo.com/2007/11/14/diy-free-and-easy-2005-mustang-throttle-response-modification/

 

[Charlie Sheen]

...everytime I hear "drive by wire" I get confused and have to think a minute...

Think of it this way - drive-by-wire vs. drive-by-cable.

I'm sure Herknav will correct me if I'm wrong, however, IIRC drive-by-wire is a derivative of fly-by-wire, when airplanes started switching over from cable-driven control surfaces to those that received their input from servo motors.

 

[Chronos]

Drive by wire sucks. I was used to the old cables till my wife got her new car last year. Now I get my Mustang this year, same thing. I thought it was a Japanese thing, but I was wrong. To make matters worse, each one feels slightly different. With the cable you had more control in my opinion. There is a lag, and it's different for each vehicle. That's why now I notice more people at lights will take a couple of seconds to pull away. I can tell from when their brake lights go out and to when they eventually start to move (ie. Lag Time). I am a spirited driver so I find it irritating. Have to slowly push down on the pedal to avoid that jerky start if you hit it too fast. I'm gonna try the tape idea and see if it helps.

 

[NastyStang113]

Drive by wire sucks. I was used to the old cables till my wife got her new car last year. Now I get my Mustang this year, same thing. I thought it was a Japanese thing, but I was wrong. To make matters worse, each one feels slightly different. With the cable you had more control in my opinion. There is a lag, and it's different for each vehicle. That's why now I notice more people at lights will take a couple of seconds to pull away. I can tell from when their brake lights go out and to when they eventually start to move (ie. Lag Time). I am a spirited driver so I find it irritating. Have to slowly push down on the pedal to avoid that jerky start if you hit it too fast. I'm gonna try the tape idea and see if it helps.

How about a custom tuner?

 

[Chronos]

How about a custom tuner?

Look at the post by lightblade. In it he has a link for the guy that came up with a possible solution for this. He says it cannot be fixed with a tuner. He says it's a physical positioning problem, and I agree. The way I see it from driving my wifes car and mine is that the system is a simple switch where two wires make contact and tell the computer what to do. So you get no reaction until you reach that connection point where the two electrodes meet. In the old cable system you could control the TB by just modulating the pressure on the pedal. You had control from the start because there was no slack in the cable. Here there is a slack, so to speak. I think by simply sticking tape or something to close up that slack or dead space, then the electrodes meet sooner and your pressure will not be so great on the pedal so you wont get a jerky reaction. Right now since you have no idea when you will actually start to get a reaction, you may press too slight or too hard, therefor giving you all sorts of weird acceleration.

 

[Error404]

That's why now I notice more people at lights will take a couple of seconds to pull away. I can tell from when their brake lights go out and to when they eventually start to move (ie. Lag Time).

I don't think the lag time is that bad, it's only barely noticeable in some of the cars I've driven. I don't think "a couple of seconds" is lag on the throttle. That's just people not immediately hitting the gas when the let off the brake, some people may just take a second or two to switch their foot to the other pedal, or to get the car in gear. I know my Mother takes a second or so after she lets off the brake, but not my Father.

If the gas pedals had "a couple of seconds" lag, that would be horribly unsafe.

 

[NastyStang113]

Look at the post by lightblade. In it he has a link for the guy that came up with a possible solution for this. He says it cannot be fixed with a tuner. He says it's a physical positioning problem, and I agree.

My tuner fixed all my lag issues. I know a few people who tried the way that lightblade suggested and it didn't do anything for them. Some of them ended up having to buy a new module since they fucked theirs up.

 

[ixtlan]

The lag that is mentioned is only at the first movement of the throttle.
Some have it some dont.
When this issue first came up I tested mine and found it did not have any of the mentioned lag at the first movement of the throttle.
IMO it really is nothing to worry about anyway. 1/8 to 1/4 inch of the pedal movement is minuscule to me and really doesn't delay anything.
Perhaps it does to the Drag Racers at the strip but I doubt anyone is starting at a flat throttle off the line anyway.

I find Throttle by wire a bit too sensitive myself.
When I shift (auto trans) the engagement causes my foot to bounce slightly (I run +5% pressure increase) and I get shall we say "Throttle Whip" because of it.
It is sometimes annoying as hell.

 

[Mike@PowerHouse]

Drive by wire is a pretty complex subject. There is quite a bit of tuning and failsafes built into it.

The short version is that some drive by wire systems use a pedal follower - the electric version of a throttle cable. Press the throttle 75% and the throttle opens 75%.

Ford used a torque-based drive by wire system where we are able to command different amounts of torque based on the load/rpm of the engine.

Think about this - if you want to make a heavy truck "feel" faster you can modify the DBW to give more throttle opening at higher RPMs.

Or how about this - when you go up in higher altitudes you lose power. So why not command more torque at higher altitudes?

The possibilities are endless.

You can imagine this is a bit more complex than a pedal follower but also much more complex and flexible.

Wes

I am going to elaborate a bit...
Basically, the ECM looks at pedal position and engine rpm then looks to a look up table to find the amount of torque requested. The computer then calculates the amount of airflow required by throttle angle to create "x" amount of torque. It then opens the throttle enought to allow the proper airflow to create the requested torque.
When the throttle body is changed to a larger aftermarket unit with no changes to the tune, the engine creates a bit more torque per throttle angle than originally requested.
It also will look to the signal from the MAF to check the actual airflow amount, remember air flow is torque. The MAF is the key ingredient in any tune. The signal needs to be smooth and repeatable.

There is a margin of error in the programming also known as wheel torque error, now if we exceed this error amount the notorious "wrench" light will come on.


So the nuts and bolts of this is simple, A tuner can go into the tune and raise the requested torque by the driver, this would make the throttle more responsive.
It can actually be made too responsive, where the throttle has a hair trigger and quickly cracks from part to full throttle.

The balance is difficult to achieve and is really dictated but the actual engine combo.


Hope this helps....

 

[ixtlan]

Nice info Mike. Thanks for explaining that.
I have a question about tuning.
As my previous post states; is it possible to make the throttle less responsive to sudden minor movements of the pedal in a tune?

 

[Chronos]

So then it can be like opening up a can of worms. You get the wrong tune by someone who isn't really knowledgeable and you will start to have problems. That's what I hate about thins kind of stuff. It's never an easy fix, and the so called pros, don't always know how to handle it.

The funny thing I find in reading through the posts is that some will have the lag and some wont. What the heck would cause this phenomenon if all the pedal modules and ECMs are the same. I was thinking if it was just a pedal issue I could just have the dealer swap it out under warranty, but I certainly don't want some jughead to start tinkering with my tune if he doesn't really know what he is doing. I haven't read any FORD TSBs that address the lag issue, so I don't think they would know how to deal with it.

 

[Shortybullitt]

There are 10 points along the throttle curve. A tuner can adjust the response by upping the signal from the throttle position so that the computer thinks it is pressed farther than it really is. This is how the tuner changes the throttle response.
On the mechanical side, there still has to be the physical input of you pressing the gas pedal to move the little actuators in the pedal. Some, not all, due to variances in manufacturing, may have some "play" in their throttle. What I mean is there is a point at which you move the pedal a little bit and the car does not recognize that movement. There was a thread, maybe here or somewhere else, where the guy actually took apart his pedal assembly and made some adjustments to it so that the actual pedal, and the metal contacts inside, were moved closer to the part that detects the movement. After reading this thread I decided that I didn't want to take apart my pedal assembly.
What I did to fix this throttle "lag" was so simple it baffles me that more people haven't done it. All I did was take some double sided foam tape. using only one side of the adhesive, and taped it to the pedal arm where it enters the "little box" where the sensors or actuators are. Basically at idle, the pedal arm contacts the edge of the box that it goes into. I placed a brick on the gas pedal and applied the tape so that at idle it would prevent the pedal from moving all the way up to where it was. I made like a little bump stop between the pedal arm and the box. I actually ended up using 2 pieces of tape to get rid of any play in the throttle. Along with Bama's race tune I have very quick and more precise throttle response with no lag.
If any of you guys don't understand what I am describing here, let me know and I can see if I can get a couple of pics up after I get home.

Let see some pics of this homemade mod

 

[Mike@PowerHouse]

As my previous post states; is it possible to make the throttle less responsive to sudden minor movements of the pedal in a tune?

Yes it is possible to make the pedal less responsive.

 

[Mike@PowerHouse]

So then it can be like opening up a can of worms. You get the wrong tune by someone who isn't really knowledgeable and you will start to have problems. That's what I hate about thins kind of stuff. It's never an easy fix, and the so called pros, don't always know how to handle it.

The funny thing I find in reading through the posts is that some will have the lag and some wont.... I haven't read any FORD TSBs that address the lag issue, so I don't think they would know how to deal with it.

Ther is not a TSB in regard to this, Ford sets up the dal to be "soft" so it makes the car easier to drive, and to reduce NVH.
Making the pedal more responsive gives the car the feel of more power and quicker throttle response, that is the feel of improvement most get in a canned tune.

Adding a MAFia to a car (if the tune is scaled) like diablo reccomends, makes the throttle really bad. But any good tuner can make it right if they know not to follow the directions included in the MAF.ia.

 

[MexGT]

There are 10 points along the throttle curve. A tuner can adjust the response by upping the signal from the throttle position so that the computer thinks it is pressed farther than it really is. This is how the tuner changes the throttle response.
On the mechanical side, there still has to be the physical input of you pressing the gas pedal to move the little actuators in the pedal. Some, not all, due to variances in manufacturing, may have some "play" in their throttle. What I mean is there is a point at which you move the pedal a little bit and the car does not recognize that movement. There was a thread, maybe here or somewhere else, where the guy actually took apart his pedal assembly and made some adjustments to it so that the actual pedal, and the metal contacts inside, were moved closer to the part that detects the movement. After reading this thread I decided that I didn't want to take apart my pedal assembly.
What I did to fix this throttle "lag" was so simple it baffles me that more people haven't done it. All I did was take some double sided foam tape. using only one side of the adhesive, and taped it to the pedal arm where it enters the "little box" where the sensors or actuators are. Basically at idle, the pedal arm contacts the edge of the box that it goes into. I placed a brick on the gas pedal and applied the tape so that at idle it would prevent the pedal from moving all the way up to where it was. I made like a little bump stop between the pedal arm and the box. I actually ended up using 2 pieces of tape to get rid of any play in the throttle. Along with Bama's race tune I have very quick and more precise throttle response with no lag.
If any of you guys don't understand what I am describing here, let me know and I can see if I can get a couple of pics up after I get home.

+1 on pics, im just curious to see what was done