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Toyota “sudden acceleration” and fly-by-wire bikes

If you keep half an eye on motoring news, you’ll undoubtedly have heard about the problem that Toyota have been having on both sides of the Atlantic with “sudden acceleration syndrome”.

There was yet another high profile story on the newsdesks just yesterday or the day before, where the local state highway patrol had to help the driver of a runaway Toyota bring his car to a standstill from speeds described in the report I read as “near three figure” .

But what’s the real perspective? It turns out around 1000 incidents have been reported since 2001. Given the number of Toyotas sold and the mileage covered, that’s a tiny figure. Statistically, you’re more likely to have a tyre blow-out.

However, the interesting perspective of one article by an electronics expert was that far from being a simple mechanical fault with the accelerator pedal or the floor mats – which, let’s face it, should be pretty easy to identify and solve – the real culprit is in the engine management system.

One suggestion is that there is an unidentified flaw in a microprocessor. Not something that shows up on diagnostics, or even in day-to-day driving, but something that only produces the runaway acceleration fault under a very specific set of conditions, accounting for both the rarity of the problem and the difficulty in tracking it down.

An alternative proposal points the finger at the software, where again a unique set of circumstances flips the programming into a tailspin.

So what’s the relevance to motorcycles?

Well, quite simply, more and more motorcycles are ditching conventional control via mechanical Bowden cables and applying fly-by-wire technology.

If you think about it, it makes a lot of sense with nearly all new models being fuel-injected; an electronic throttle integrates cleanly with the injection system.

And of course, it allows new features like Harley Davidson’s Electronic Cruise Control, which appeared a couple of years back on their big tourers.

And more, for the manufacturer, it makes things simpler… and thus cheaper! No expensive control cables to fit and route during assembly!

Harley even manage to dress up the lack of cables as introducing a “cleaner look”, which is an unusual departure for a company usually keen to make their bikes look like they were put together in 1950!

Honda have even gone so far as to introduce braking-by-wire, where the company’s latest system combines ABS and CBS into one electronically-managed system, designed to prevents braking lock-ups and manage weight transfer to help stop the rear wheel lifting.

So is fly-by-wire good or bad?

Jammed Bowden cables are a well-known problem on poorly maintained bikes and they do snap if not replaced when worn. Whilst the throttle will usually shut if the cable breaks, that’s not the case if the cable jams. And of course, snapped cables connected to either of the brakes or the clutch will make stopping a little more tricky.

By contrast, fly-by-wire is seen as safer because the designers can build failsafes into the software. For example, the Harley software apparently has several layers of safety built into the system including boot-up checks of hardware condition / position, as well as constant monitoring for faults. Like cars, the bikes have a “limp home” mode or even total system shut down to prevent damage to the bike or operator in the event of partial or total failure.

But… this does pre-suppose that the new fly-by-wire hardware won’t deteriorate.

Fly-by-wire eliminates some of the moving parts, but there’s still wear and tear to the sensors themselves likely to occur – they’re far more exposed on bikes than cars. And what will happen when the inevitable deterioration of the wiring loom occurs? Wiring is not a strongpoint on many bikes!

Longterm we’ll have to wait and see, but electronic faults in the engine management systems of cars are notoriously difficult to trace and fix except with wholesale replacement of the entire loom and processors, the cost of which rapidly takes cars just three or four years old “beyond economic repair”. Great for sales of new cars, not so good if you happen to own the lemon in question.

The economics of repairing bikes too has been getting less and less viable over the years, and I can’t see fly-by-wire improving this trend.

Just as has happened to cars, I can foresee the demise of the twenty year old bike that until recently has been easy to keep roadworthy with affordable parts.

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