How are by-wire throttles controlled??

[Hen]

While daydreaming about some long term projects, I got to thinking about by-wire or electronically controlled throttles. I understand their function and advantages, but what I don't know is how they are controlled (I've never pulled one apart either).

Has anyone played with them? Do they use a stepper motor? PWM? Servo control? How many control wires do they use? Would it be convceivable to build a home made controller for one of them?

And does anyone have suggestions for a good, easily available and cheap by-wire throttle?

I tried a while on Google, and found a few mentions of PWM and servo controlled throttles, however further info is always good.

Hen

[Draven]

swap me something to bolt on to the 2j in place of my by wire system and you can have it

[kingmick]

swap me something to bolt on to the 2j in place of my by wire system and you can have it

and the computer to run it

I have a throtle pedal setup here for one! There are not cheap either around the $1000 mark for a bloody potentiometer on a pedal assembly.
This ones off the latest Kenworth 604 semi, hahahaha making a Tig foot switch out of it!

Its a great idea but i would be waiting till it becomes more common place and the aftermarket computers start running them.
I only say this from a cost point of view and saftey poin of view.

[mrshin]

Motec has been able to control one for several years now.. Grab a pedal and throttle from a suitable donor car, and let the fun begin.

[kingmick]

Yep and it will be a very cheap setup! hahahahahahahahahahahah

Suppose i should add, you would be mad to even use it in a lemans car, as you have electrical parts to go wrong were in the best setup the cable can only snap and take two seconds to fix

[mrshin]

Well, I can MAKE it cheep:

[kingmick]

Ok ill have 500 cheap motecs thanks!hahahahahah

[slide86]

well basically there is a pedal position sensor thats in the cabin. that basically tells the ecu what positin the throttle is at. ie 15% down. this then gets transfered to the throttle body which has a small motor to control the throttle butterfly.

the system is ok, but its a bit delayed. you put your foot down and then a few seconds later after the ECU has all the calculations done, then it opens the throttle. it can get a bit annoying

[kingmick]

"pedal position sensor" is a potentiometer, same as a TPS.

[kingmick]

well basically there is a pedal position sensor thats in the cabin. that basically tells the ecu what positin the throttle is at. ie 15% down. this then gets transfered to the throttle body which has a small motor to control the throttle butterfly.

the system is ok, but its a bit delayed. you put your foot down and then a few seconds later after the ECU has all the calculations done, then it opens the throttle. it can get a bit annoying

Mate crap, you have never driven one have you? or know anything about it?
If the 540 BMW i have sitting at home did the claimed 5.2 or 0-100 that would mean they could take a secound of that time using a cable and save themselves a tens of millions of dollars!
Stop learning of web sites or bad ones!lol

p.s a few seconds would make the 540 do the 0-100 in 2.2 seconds with a cable! i want one of those 540's!

[Draven]

I have to side with mick here... my jza80 (vvti - drive by wire) has at least as good response as my throttle cable 1j. I don't really notice it's there to be honest.

[thechuckster]

what no-one's actually addressed is what kind of drive mechanism?

e.g. is it a stepper motor (like a 1G aux-air-valve) that requires electromotive force to open AND close it (highly unlikely) or is a PWM-driven solenoid (like an XF idle-air valve) that rotates or pushes a lever and relies on a spring to return the a home position (more likely as electrical failure causes closed throttle).

Reason i think it's the latter is that drive-by-wire throttles (that i've seen anyway) have a TPS on the opposite side of the driving unit - so the the driving unit doesn't do any positioning - ergo it's a PWM-driven solenoid.

cheers,
charles.

[Draven]

I'm not going out to check now, but from what I can remember you're right chuck - TPS on opposite side to drive unit

[kingmick]

Same here, if we dont use it racing i aint checking it now in the cold!hahahaha
but if someone really wants to know ill take picks of the BMW setup in the next few days when i get a chance!

[roadsailing]

i'll have a look at the BA or VE setup at work when i get the chance, i have a few ideas how they work and should work, but wont post up opinions just yet.

i was all for the idea until i put on a working throttle body.