Fly-By-Wire Throttle Complaints?

[SLugg]

Can someone explain what is meant by fly or drive by wire. I haven't heard of it before. I have heard planes are fly by wire but never really knew what it meant.

there is no throttle cable anymore , the pedal under your foot controls a pot thats feeds current to the ECu directing it to rotate the electricaly controlled throttle. It means the ECU can control the fuel timing and TBody more accurately for optimum economy and power

 

[improvize]

Ahhh OK. So it should be better then? Why would people complain about it?

Also makes me wonder if the cruise control make the accelerator pedal move any more. Anyone want to comment?

 

[VN_Luke]

i wonder what will happen in a little while when those pots get dirty and start contacting/non contacting when they shouldnt :s

does this system include things to stop you from hurting the car? i.e. cold start, foot to the floor, won't rev high? etc?

 

[SLugg]

Ahhh OK. So it should be better then? Why would people complain about it?

Also makes me wonder if the cruise control make the accelerator pedal move any more. Anyone want to comment?

no more cruise cables the cruise is controlled by the ecu direct to TB and the pedal dosnt move

 

[Marks-VY]

I have a VY manual and a VT2 auto. In both cases the engine does what my right foot asks it to do.

I do a lot of interstate travel and the standard hire car of choice is the VZ Exec. Every time I get in it I instantly notice the lag in throttle response. It is not a big issue on public roads although should you find yourself in the "traffic light drags", I'm sure it would have an effect. The way to compensate is left foot braking although I have read somewhere if you do this too hard/too much, the car can go into limp mode.....

And you are right improvize, the cruise control does not affect the pedal which is also disconcerting when my two cars have pedals that drop under cruise control acceleration. Just a case of getting used to it.

 

[Doctor Bob]

Its called Torque on Demand, it will control the throttle blade according to how its programmed in the PCM, it definitely feels different but i wouldnt say it has any lag as such, the maps it uses are interesting as at 20% pedal travel you will only get about 3 or 4 % throttle blade, if you redo the map to 1:1 the car drives like crap, really snatchy & generally ugly.

Rob

 

[theautomationguy]

Well now I know why my VZ has throttle lag. My wifes 145kw VS is quicker off the mark than my 175kw Cross 6 but the VS had a tendancy to stand still and spin one wheel. In fact I thinks I feel safer in my old VG 127kw ute with LSD punching into a gap in traffic. I also think the economy is better in the VS might be my imagination only getting 16l/100 around town & about 12l/100 on freeway. I am a bit of a lead foot. No problems accelerating once moving only from standstill.

 

[cliffo78]

i wonder what will happen in a little while when those pots get dirty and start contacting/non contacting when they shouldnt :s

does this system include things to stop you from hurting the car? i.e. cold start, foot to the floor, won't rev high? etc?

For VP_LUKE and anyone else who is interested or wishes to add their thoughts:

Yes, the VZ Alloytech:
* still will not start up with WOT (as with Ecotec)
* is rev-limited to a shade over 4000rpm in Park or Neutral (on the auto, not sure about manual)
* if you have any throttle opening whilst changing between reverse and drive it will momentarily drop the revs back to idle to relieve strain on the driveline/transmission
* will reduce throttle (torque) input if brake and accelerator are pressed simultaneously (eg, when trying to "stall up" for a quick launch)
* low speed throttle inputs (eg, parking, reversing a trailer) are a little lumpy due to the throttle lag

Overall when jumping from my wife's VT into my VZ, the VZ has a much more responsive feel, and requires a lot less pedal travel to get it going. This is mostly due to the variable "ratio" of input provided by the ECU, whereas the VT has a more linear behaviour as the throttle body and the pedal have a direct link. Obviously the increased responsiveness in the VZ is also in part due to higher power output and a flatter torque curve, but this is more relevant to situations where heavy acceleration is used.

In response to your other point, fly-by-wire throttle is not new in the automotive industry (on a global scale), so I am not anticipating there will be many issues with failures on VZ's and future models. Like many electrical components they will probably require periodical checking and replacement before they start to fail.

 

[Troy711]

* will reduce throttle (torque) input if brake and accelerator are pressed simultaneously (eg, when trying to "stall up" for a quick launch)

unless you get the wheels to spin before it drops the revs down

 

[cliffo78]

unless you get the wheels to spin before it drops the revs down

True, as long as you reduce braking pressure (enough to just hold the front wheels steady), I assume? And if so, the low-rev torque availability should allow the rear end to light up fairly spectacularly? I haven't actually tried this yet.