May seem like a stupid question but what is the reasoning behind the drive by wire throttle pedal, is it so that the ECU has more control over the engine or the emissions or something???

 

Ive said this for a long time. A cable when it breaks means the car goes nowhere .. A Computer failing can do anything. There have been many incidents in the Air Force when I served that highlighted this. This is why modern aircraft can have as many as 5 backup systems. Bet car makers dont fit backups.

However the stories of people flying thro junctions and cars hitting 100mph+ are just because the driver has no idea / stupid .... None of them heard about neutral or turning off the ignition ?

 

Yes, possibly a technical advance too far when placed in the hands and feet of the majority of the world's car consumers who treat their "autos" as just another white goods consumer item.

Cars have become far too easy to drive and comfort and ride levels, not to mention power assists has isolated the driver from reality ~ and sadly, some pay a price for that every day ....

I did have a throttle cable stick fully open in an EFi montego a work colleague asked me to drive he was considering purchasing. A good car and the previous owner, a nice old boy who had it for years, had obviously never put the pedal to the floor whilst he had it. The build up of fuel varnish and crud residue in the area where the throttle buttefly valve had not reached for years stuck in that crud fast when I floored the pedal. This was away from the lights, and some laddos in a souped up wotnot fancied their chances alongside. My friend asked me to give it some so I did. Soon at max revs in first, I changed into second with a stuck wide open throttle and engaging the clutch produced a loud chirp from the front tyres by which time I had realised the throttle was stuck wide open ~ we were nearly flat out in second leaving laddos for dead before I realised what was wrong and reached forward and switched off the ignition and coasted for while into a convenient lay by.

Where my friend then queried why I had driven in such a way a car he was seriously considering buying ... I then explained what had happened and a few minutes later, using a pen knife to undo the hose to the throttle body, I was able to free up the valve so that it would close easily. He bought that Montego Estate and was so pleased with it, bought another for his wife and both replaced the pair of heavyweight Volvo estates which were proving costly to run. He asked me to try this car for him because he saw that for years, my Montegos never missed a day at work and had he not observed that, would never have considered buying a British car.

Moral, it's not only the big things that count when maintaining a car ~ any car ~ had that happened to another driver with less car 'nouse' gawd knows what could have been the outcome.

Yes, I believe you can have too many advances in technology ~ an advance too far may be just that!
..

 

A mechanical throttle has far more potential to stick open than a "drive by wire" one. In most cases, where a fault is detected, they go into failsafe and the car simply won't go.

A pretty silly article IMO.

 

Not a silly article really. Makes a good point, along with people in this thread.

Yes, drive by wire does go into limp or shut down when there is an error. And yes, mechanical throttles can stick open more easily. However, an electric throttle can snap or break (or get damaged in a way) far more easier than a manual one.

When your manual throttle decides to play up (sticks, or snaps), it's a quick jobby underneath the Bonnet. This isn't the same with an electronic one, this involves getting towed to a Dealer and lots of money being involved if it isn't under Warranty.

 

Not a silly article really. Makes a good point, along with people in this thread.

Yes, drive by wire does go into limp or shut down when there is an error. And yes, mechanical throttles can stick open more easily. However, an electric throttle can snap or break (or get damaged in a way) far more easier than a manual one.

When your manual throttle decides to play up (sticks, or snaps), it's a quick jobby underneath the Bonnet. This isn't the same with an electronic one, this involves getting towed to a Dealer and lots of money being involved if it isn't under Warranty.

Probably should do this, but what is it with the Toyota problem then that doesnt ?

 

As far as I can understand the Toyota issue is with the actual pedal sticking in place so as far as the dbw system is concerned the driver is just holding the throttle as normal.

Basically there is a friction plate on the pedal mechanism its self which is designed to provide a degree of resistance to the pedal movement so the driver experiences a consistant weighting to the pedal. This plate wears and sometimes actually sticks.

Although the pedal system is designed to be used by dbw cars, ironically the issue is a mechanical rather than electrical one and a similar pedal fitted to a conventional throttle (which they may well be) would have the same issue.

 

As far as I can understand the Toyota issue is with the actual pedal sticking in place so as far as the dbw system is concerned the driver is just holding the throttle as normal.

Basically there is a friction plate on the pedal mechanism its self which is designed to provide a degree of resistance to the pedal movement so the driver experiences a consistant weighting to the pedal. This plate wears and sometimes actually sticks.

Although the pedal system is designed to be used by dbw cars, ironically the issue is a mechanical rather than electrical one and a similar pedal fitted to a conventional throttle (which they may well be) would have the same issue.

Ok, except the article referred to goes on to say

"Toyota ( TM - news - people ) blamed floor mats, the gas pedal and the brake mechanicals for its problems. But some customers assert, and government safety officials seem to be implying, that a software glitch is causing the throttle to kick wide open when the gas pedal is not being touched. A software glitch, a ghost in the machine, is to blame."

 

Drive by wire systems are fine and should not be dropped. There are many reasons as to why they are used now and part of it is to do with all of the green hippy tree huggers of this world.

As emissions limits become ever more stringent, the best way to control fuelling is via fly by wire systems that control stuff and allow for optimum combustion performance etc.

Most fly or drive by wires have systems in there that should things "stick" the second you touch the brake pedal, the fuel signal is cut and the car stops normally with no extra effort as the engine has been "cut" from the car. Try doing a bit of left foot braking to see if your car has this function (none of the MGR vehicles have it by the way apart from the diesel cars L series and M47).

Try accelerating a bit and then gently touch the brake pedal to get the brake switch to activate and if the engine stops accelerating, you have the power overide system in there.

Now, I'm not sure what is fitted to the Toyota's and Lexus vehicles, but FFS, how difficult can it be to knock your gearbox into neutral be it manual or automatic, or twist the key and turn the engine off????????

If there is a fault detected then the system should as someone has said, go in to limp home mode or stop you from going any further, but you as a driver will be notified by a MIL warning lamp on the dashboard.

There is really no cause for alarm and the people who are fueling this are all in the States if you've noticed. The US car industry is in shreds at the moment and they're looking for anything to help build their industry back up so unfortunately Toyota are suffering. The only real problems have been noted in the States, no where else in the world, the deaths are are all in the States, no where else!!!!!!!!!

Fly by wire is safe, we all get on planes where everything is fly by wire and no one bats and eyelid!!!

Nic

 

Now, I'm not sure what is fitted to the Toyota's and Lexus vehicles, but FFS, how difficult can it be to knock your gearbox into neutral be it manual or automatic, or twist the key and turn the engine off????????

Nic

Select neutral or turn off the engine .... :rofl:

However, it is obvious that that is far too technical for many of the "White Goods" car consumers otherwise those real scenario fatalities would not have happened.

After all, why drive carefully as you must in old less safe cars, my gizmos will look after me and my car has twentyseven more safety stars than yours so when I crash into your car, guess who'll walk away smiling...

Anyone reading what I have just written who feels that scenario would never come about, even subconsciously if never admitted, is a poor observer of their fellow men and women. I have known TWO work colleagues driving modern cars to admit just that when discussing their choice of cars. Not in the exact same words but, the meaning is the same. I'd bet a nice few quid that mindset is not restricted to those two individuals. I suspect there are thousands who we share our roads with who whether admitted or subconsciously, chose their vehicle with those values in mind and drive them accordingly. How else can you explain all the X5s and other monster truck types parked inconsiderately and selfishly just before 9am at the local school.

Toyota have very successfully targetted the "white goods" car consumer. Trouble is, there's a case to consider that just maybe, the vehicles they produce are more intelligent than some of those who buy them.
...

 

This whole Toyota thing is making my blood boil at the moment as there is just no need for it.

I found my self absolutely screaming at the radio yesterday when one of the "so called USA victims of sticking throttle in a Lexus" said that she "put the car in reverse and it stayed in reverse and sped up to 100mph".

Now, forgive me, but where on gods mostly harmless blue green planet out in the far off reaches of the western spriral arm of the galaxy find somewhere where she could go backwards at 100 mph without hitting something??????????????

MORE importantly, it is not physically possible to make a car go backwards at 100mph because the gearing won't allow it and as the engine is screaming at 7000rpm and you're doing 30mph ish tops how could you get to 100mph??????

Of course the chuffing car stayed in bloody reverse, you put it there, it doesn't decide to get out of gear itself!!!!!!!!!!!! And it would also suggest that when reverse was engaged by her right arm (being LHD) she applied full throttle to go backwards! WHO IN THEIR RIGHT MIND DOES THAT???!?!?!?!?!?!?!? And at what point didn't she put the car into neutral and I'm sure that I heard her say that she "rang her husband on her blue tooth car phone system" as she wanted to hear her husbands voice and pray to god.

Now, let's look at the events shall we:

Ignition and engine on.
Engage reverse
Rocket backwards at 100mph in a car that can't physically do it or have the space to do it.
Have the presence of mind to dial her husband on her mobile via the bluetooth system whilst still rocketing backwards and not hitting anything.

I mean COME ON!!!!!!!!!!!!!!!! Why has no one picked up these glaring and obvious Bull$$$t claims from the Americans.

All of the things fitted to cars at the moment are contricbuting to this unbelievable mentality that nothing can go wrong and it's the legislation that's causing it, but the bunch I have to work with to enforce this legislation don't seem to be making the links at the moment because they're too busy bowing down to people who demand greater safety and lower speed limits etc from knee jerk reactions to stupidiy and not learing that the road is a dangerous place in the first place! It just beggars belief that this is happening.

I'm sorry if I've just climbed onto the biggest soap box you've ever seen, but doing the job I do, I have to deal with it all and I CANNOT understand why people think that just because there is a perceived problem they don't know how to deal with it.

What makes the car move in the first place?? The link between the engine and the wheels, oh what's it called, oh yes, the gearbox. How does the gearbox make the car move? By engaging a gear. How do you stop the engine having a direct effect on the wheels and direction of travel? PUT IT IN NEUTRAL!!!!!!!!!!

Sorry, rant over (for a bit) :***::***::***::ziplip::cus::cus::twak2::twak2:

 

Personally i think cars and bikes are becoming too easy to drive. When a computer does everything for you and you never need to learn to drive around problems, when problems do happen you have no idea what to do.

In the US most of the freeway crashes are due to drivers falling asleep ... They have big comfy cars, automatics and cruise control .... Leaves the driver nothing to do so they fall asleep.

 

Personally i think cars and bikes are becoming too easy to drive. When a computer does everything for you and you never need to learn to drive around problems, when problems do happen you have no idea what to do.

In the US most of the freeway crashes are due to drivers falling asleep ... They have big comfy cars, automatics and cruise control .... Leaves the driver nothing to do so they fall asleep.

So true, Too much safety is actually making it more dangerous in certain circumstances ! Rep added !

 

Imagine a set of three teeth on a cog and the corresponding 2 on the throttle pedal itself. The teeth are getting stuck between each other and not allowing the pedal to move freely from home to on position (for want of a better description).

The introdution of a small metal "shim" aleviates this problem so the teeth don't get wedged over time. There are lots of environmental issues that cause it believe it or not over time. There is wear on the teeth, but also the cold weather hasn't helped and it's all happened over the winter months if you've noticed!

It doesn't suddenly happen, it's a gradual thing and the throttle pedal gets gradually stiffer and stiffer and then it sticks an won't go home. Then someone stands on the throttle as a reaction and shoves it to the floor and we all know what happens then.

 

You may have more information than I do, (regarding 1 makers recalls) but I am led to believe there is more than 1 problem.

1 may be mechanical. 1 isnt !

Time will tell ?

 

I am led to believe that there is more than 1 problem, covering more than 1 make of car too !

I dont have all the info so cant confirm or deny, but it will be nice to see (for everyones sake) the final definitive answer(s).

As far as this thread goes, does the system fail safe, correctly, under all circumstances? If so, its safe; if not then its not ! Simples !

For fly by wire generally; if it fails safe correctly under all circumstances there is no problem with it. BUT, it has to be UNDER ALL CIRCUMSTANCES !

 

From what I can fathom out, all electronic systems in cars will fail safe - however, in the case of the throttle pedal, it is mechanical before it becomes electronic therefore the pedal when it sticks will not fail safe because it's jammed.

The electrical problem not throttle related is down to software in the Hybrid cars, the regenerative braking system doesn't kick the ABS system out fast enough or vice versa so I understand.

 

You say fail safe, but what happens when it doesn't fail, but thinks it is correctly giving you full throttle when it shouldn't? Is it error safe?

The other issue is the throttle's electrical actuator's reliability. OK so a throttle linkage can jam, but which is more reliable, a simple direct mechanical throttle linkage, or an electrical actuator? especially if the vehicle isn't being regularly checked and maintained.

 

Just thought i would bring this back up.

It does seem like its a fly by wire system that isnt failing safe !

Not a mechanical fault at all apparantly ?