fly by wire throttle

[Fred]

John, I discovered a minor bug in the last release this morning and thought I'd share it with you as an example. In this case it was 100% benign, but it illustrates the point quite well.

Code: Select all

	// Serial experimentation
	sendSt("Log: ", 5);

I had 6 in there instead of 5. The serial code was reading a random byte from memory and sending it out on the serial line. If that had been a +1 error on some receiving code it could have been writing a random number from the serial stream to a random location in memory. It is that easy to make a mistake. I've had a few over the last few months, some bad, some mild, and all caught early on, but that is not always going to be the case.

In this case we just got :

Log: ^@Sec=00913

instead of

Log: Sec=00913

in the log file but it could have been worse.

That should clarify it pretty well :-)

Fred.

[thebigmacd]

There's a pretty simple way of making it safe...an end switch on the throttle pedal (or in the throttle position pot). When the pedal is released, it opens the power circuit to the throttle motor.

Or if you want to get really fancy, use a second brake light switch, and wire it in parallel with the gas pedal switch, so that it will only cut power to the motor if both the gas pedal is released and the brake pedal is pressed. This way you can still heel-toe.

[johnd]

Are any new cars still made with throttle cables?

The only Fly by Wire safety issues we can recall are Volvo, in the US of A when their cars suddenly took off and hit something but this was traced to pilot error.

If you try and "blip" the throttle, when stationary, in a modern lorry it will not rev very high. This stops bored and stoopid drivers from pretending that they are racing..

Perhaps all ecu's will have this as an option so you can let the kidz borrow the car, or will it be std to reduce emissions, and save fuel.

Race cars are faster with Fly by Wire, which is why they stated to use them..

http://www.vems.hu/wiki/index.php?page= ... reThrottle

only new cars in UK with cable throttle now will be the very small sub 1000cc town cars .everything else including diesels have some sort of FBW--
It is rumored that ESP will soon become a requirment for all EU spec cars ,and that cannot work without FWB.
this is why i am suggesting you think about it from the beginning ,even if is not used ,as all engines have or will have it soon ,and cost to buy a t/b and make a cable set-up in a car not meant for it somehow goes against what you are trying to do -- So please include an output to run a FBW--pwm I would suggest--but I leave that to you
there is also a large stock pile of these units in the car dismantlers ,as they don,t go wrong very often--so you can buy them cheap.
the main reason ehy bikes have both fbw+ cable is for driver afety--not because they think it will jam ,but the modern bike engine is so good that snapping the cable throttle open would result in throwing the rier off ,also inthe wet they would be totally unridable.
I know the gp riders look wonderful and ride to the limit and make it look so easy --thats cos they are only doing half of it --the major part of the throttle control is done by the ecu +FBW .relative to gear selected --front + rear wheel speed ,angle of lean on the bike .the way the FBW opens is set differently for every gear ,yes they can overide the closing of it ,but the ECU is what makes them look good,traction control in the old way by cutting fuel ,retarding timing ,cutting spark etc is too jerky and would cause loss of traction ,so they use the ecu controlled t/b along with ingniton retard ,and fuelling and other sensors i have mentioned.
not an afternoons job setting one up for a new track!! and of course toally dif set-up for the wet!!

[Fred]

everything else including diesels have some sort of FBW

LOL, a strange concept indeed to limit air to a diesel. I hate electronic diesels, it removes their very best feature : durability in ANY environment.

It is rumored that ESP will soon become a requirment for all EU spec cars ,and that cannot work without FWB.
this is why i am suggesting you think about it from the beginning ,even if is not used ,as all engines have or will have it soon ,and cost to buy a t/b and make a cable set-up in a car not meant for it somehow goes against what you are trying to do -- So please include an output to run a FBW

I'm not sure what you think I am trying to do, but I am trying to provide a system that people in poorer places and students etc who aren't lazy, but are poor can use to get the best possible performance from their engine for the least money. I'm not much interested in helping corporations make cash on it supplying it to owners of high end modern cars. Most engine swaps and EFI swaps are on older cars and those with std throttles anyway. If the high dollar boys want FBW, they may pay for it :-) The point of this site is the DIY part. That includes the boards, assembly, wiring, etc etc etc. Do It Yourself at home, in your drive/garage, on a budget at night while studying/working etc. That is the spirit in this project. Some people miss that point. Another is adapting and engineering around OEM monstrosities that are supplied on modern vehicles. Adding a throttle is nothing to a true blue DIYer, at least not in New Zealand it isn't! Things certainly are a bit different here though, I've stayed here long enough to know that now.

However, I'm not saying I won't, I'm just saying it's months and months and months away and way way way down the bottom of the list just above self tuning to flash.

Secondly, it's a "main loop function" in that it just uses variables that are available in a non time critical way to do what it is doing just like boost control and idle control and everything else that isn't dwell, advance and pulsewidth.

Anyway, point noted, FBW is a maybe one day thing, YES. FBW this week, month, year, very very very highly unlikely.

It's a minority thing anyway, so it has to wait for everything else that WAY more people want like idle and boost etc.

Fred.

[MotoFab]

everything else including diesels have some sort of FBW

LOL, a strange concept indeed to limit air to a diesel. I hate electronic diesels, it removes their very best feature : durability in ANY environment.

This is a little off-topic. Are you talking about 'pumping losses' by having a throttle, Fred?

- Jim

[Fred]

everything else including diesels have some sort of FBW

LOL, a strange concept indeed to limit air to a diesel. I hate electronic diesels, it removes their very best feature : durability in ANY environment.

This is a little off-topic. Are you talking about 'pumping losses' by having a throttle, Fred?

No, I mean the ability for an old style injector pump traditional diesel to run UNDER WATER with only a tube of fuel and a tube of air (no battery power at all). I have had my life saved by this once, and in any serious situation (boats, commercial vehicles, off road vehicles etc) it is absolutely invaluable.

I imagine the manufacturers are using them to avoid pumping losses, however that is annoying too, diesel engine breaking is a fine feature that should not be removed by choking the air supply.

Fred.

[MotoFab]

No, I mean the ability for an old style injector pump traditional diesel to run UNDER WATER with only a tube of fuel and a tube of air (no battery power at all). I have had my life saved by this once, and in any serious situation (boats, commercial vehicles, off road vehicles etc) it is absolutely invaluable.

I imagine the manufacturers are using them to avoid pumping losses, however that is annoying too, diesel engine breaking is a fine feature that should not be removed by choking the air supply.

Oh, I get it, that level of durability.

And about 'pumping losses', it originally sounded like you were talking about the common belief that a throttle increases pumping losses.

[johnd]

It's a minority thing anyway, so it has to wait for everything else that WAY more people want like idle and boost etc.

the way the world is going now and the way car values drop there are so many perfectly good modern engines which give good power and economy sitting in scrap yards ,lighter than old units better power in std form
far cheaper to fit one of these than even rebuild an old engine .
Its far cheaper now to get a good s/h unit than rebuild most engines --thats where I,m coming from -
as for lots of diy peeps wanting boost control + idle --you can all that with the one unit --FBW --so I wouldn,t write it off as being only for the new car owners who can afford and AMG conversions etc ,or the like --
you are almost sounding like you would begrudge someone with a newer car fitting a diy unit to to --is this reverse snobbery?? LOL..
its the fact that all these newer engines have coded -can bus ecu,s , vvt, double vanos etc that stops them being fitted in kit cars + home builds ,cos the thought of buying a GEMS,or MOTEC etc to run them + costs of someone to set them up is too much .
I maybe have misinterpreted your mission statement
I don,t see the point in making another megasquirt type thing --when with the same effort you could be making something that would conpete with any ecu system on the market ,and yet have it as a diy unit
its like making light bulbs when the world is converting over to LEDS.

[Fred]

the way the world is going now and the way car values drop there are so many perfectly good modern engines which give good power and economy sitting in scrap yards ,lighter than old units better power in std form
far cheaper to fit one of these than even rebuild an old engine .
Its far cheaper now to get a good s/h unit than rebuild most engines --thats where I,m coming from

Cheap is only one factor when choosing an engine. I prefer to choose based on performance capability and strength also. Most modern engines have pencil rods and are built with slim margins to make the power that they make and little/no more. I'd take a 1988 - 1998 engine over most modern stuff anyday. They were building them flowing well enough then, and still strong enough to take a beating. Modern engines are good for stock form and emissions and little else without major work. This isn't specific to any given manufacturer or country of origin either. All of them have gone that way for legislative reasons. New != Good.

you are almost sounding like you would begrudge someone with a newer car fitting a diy unit to to --is this reverse snobbery?? LOL..

No, it's poetic justice. Why should someone with a pocket full of cash benefit from my work when my account has 5 quid in it and I'm working for free? IMO they shouldn't, if they can afford to pay, they should crack out the wallet and stop being tight. I do LOVE the way well educated POHMs speak (apparently a minority) and aspire to speak the same way, so in that respect I am a snob. I'm a snob when it comes to tech too, only the best will do. However I loath the attitude that comes with the good manners and elocution lessons etc. The only thing I loath slightly more are all the uneducated POHMs that can't speak english as well as this middle class kiwi ;-) Poor form old chap, as it were, etc, old boy. So, yes, reverse snobbery if you like. I'm OK with that, are you?

double vanos

= Pencil rods.

etc that stops them being fitted in kit cars + home builds ,cos the thought of buying a GEMS,or MOTEC etc to run them + costs of someone to set them up is too much .

This is not a realistic limitation unless the person making the decision isn't aware that for 5 quid they could have a laser cut adapter to a reasonable sized throttle of an older engine. Vanos etc is easily controlled.

I maybe have misinterpreted your mission statement

This is possible. I said I want an open platform for DIY type people to be able to build and modify in any way they want. What I meant by that was that I wanted some good functional firmware that does the basics VERY well and can easily have cherries added on the top at a later date that is licensed under GPL such that anyone can build hardware for it. This would mean free hardware designs, and it will also mean cheaper commercial hardware designs because of competition. The fact that my code is commented and structured and readable means anyone can modify it with relative ease. This makes good engine management accessible for those who aren't on the right side of the Buckingham Palace gates.

I don,t see the point in making another megasquirt type thing --when with the same effort you could be making something that would conpete with any ecu system on the market ,and yet have it as a diy unit

Firstly, what exactly is wrong with MS in your eyes? Secondly, it WILL be able to compete with any similarly speced ECU and give them a good thumping in many cases, however that is not the goal. There will always be a MOTEC that does it a little better. You need to aim for where you want to aim for, not where the jones are at. The goal is to satisfy MY needs and the needs of the sort of people I care about. Much less the sort of people that as Pink Floyd put it are "riding the gravy train".

MegaSquirt was and is great for what it is and was, however some of us need a little bit more. B&G&J&K are working on delivering that little bit more, but with an associated price penalty and the same lack of freedom. I felt this was unacceptable and decided to do something better than existing MS units at the same or less price. I want MS++ and M$--. I will get what I want :-) Like MS, we are still working with what is effectively an under powered processor though. At least compared with MOTEC or Mazda or BMW etc etc. It has real limitations and that is part of the fun. Aiming too high will kill the effort. It needs to be cheap and accessible and free for mods to appeal to the type of people that I want it to appeal to.

Still interested to hear what you see as wrong with MS though, do tell.

Fred.

[johnd]

Cheap is only one factor when choosing an engine. I prefer to choose based on performance capability and strength also. Most modern engines have pencil rods and are built with slim margins to make the power that they make and little/no more. I'd take a 1988 - 1998 engine over most modern stuff anyday. They were building them flowing well enough then, and still strong enough to take a beating. Modern engines are good for stock form and emissions and little else without major work. This isn't specific to any given manufacturer or country of origin either. All of them have gone that way for legislative reasons. New != Good.

I bet you think the ford pinto engine is a good engine . name me a good engine from that era

the reason why you need to do major work to get better than std is because std is so good .
it was easy with a mini engine to 50%increase --it was so crap and designed in the 40,s anyway--
If you have a 2.0 engine giving 200bhp in std form --how much more you think your going to get without spending serious money --a mega squirt won,t do it --doubtful you will ever get one to run as good as std ecu . certainly not with the minimilsitic approach to sensors to are trying to do.

this should be a wake-up call for all of you diy men -if you are going to change the ecu on the car --then do it before you fit the lumpy cams etc .
when you get it to run as well and economical as std ecu --then you know you have got to grips with thing and have an ecu system that works .
fitting the diy ecu after you have modifed the engine you are giving yourself all sorts of varaibles and maybe the short comings are not the spec of engine but in the way the ecu is working --doing it as i suggest means you have a bench mark to aim for ,and you will know that you have done it right when it runs as good or better than with std ecu
I think this is where i stop posting cos you are still living in the dark ages --
car makers are getting more power now from std engines and doing it with more economy --that is by anyones judgement a good measure of effiency--
I am old enough to remember when engines only lasted 40-80k-now modern engines just don,t wear out if kept serviced correctly .