Car faults in perspective: What can possibly go wrong….again..

One in a million.
My boss told me “so that means your design will defiantly kill two people per year!”.
That was 20 years ago, when I was a fresh faced engineering graduate in my first job at a global car maker. I was designing bits of engine management system, and as ever I had gone through every type of conceivable failure and worked out how well it was protected against. But one very obscure scenario involved the car stalling on a hypothetical level crossing near a strong radio transmitter, a bit tenuous but it is a situation that could happen, I had gone through the figures and worked out that it was a million to one chance that the engine would not restart, resulting in something bad involving a train and sudden localised distortion to the car (ok, a crash).
I thought that this was a remote chance, but my then boss pointed out that the systems would be put on about 2 million cars per year in Europe, hence his terminal conclusion.
I redesigned it. No one had to die.

Cars made in high volumes are used in every sort of environment possible, testing for all occurances is a huge investment.

But even so, I am sure there could be even more obscure situations I had never even thought of, I probably could have spent years going through more and more complex scenarios, but the the car would never have been made. So we have to draw the line somewhere.

How common are uncommon faults?
Cast your mind back to Toyota’s ‘sticky pedal’ problem, millions of cars work fine yet a handful of unverified complaints necessitated a total recall. You just can’t take chances, even if almost every car is perfect.
Of course Toyota are no worse than Ford, Mercedes and all the rest, all volume products suffer from occasional problems, largely due to the scale of production and of course because we want our complex cars dirt cheap, and that’s not going to change any time soon.
When an industry has to make very complicated machines with highly sophisticated features that are used by the general public who have only minimal training, and have to endure a vast array of harsh environments including salt spray, Arctic freeze, road shocks and days on end in scorching sun, things are going to be difficult. And when this problem is massively compounded by having to make the car as cheap as possible, something has to give.

New ideas like this Rolls Royce EV undergo a huge amount of testing before any customer is allowed near it.

Times this set of problems by the millions of cars made every year and the law of averages is definitely not on the side of car makers. If you think about it, the mere fact that when something does go wrong it makes the headlines tells us something about the utterly fantastic job that all these companies usually do.
If the average Joe knew anything of the vast amount of sheer hard work that goes into creating cheap, economical, useful and reliable cars they would bow down in reverence, and those that fancy their chances at suing for spurious accidents would hang their head in shame.
But hardly anyone knows about all that fantastic engineering work, it doesn’t make sexy TV programs, it’s not vacuous and glamorous enough to make it into the glossy magazines. So every one just accepts that every machine should work perfectly no matter what, and are utterly surprised on the very rare occasion that it doesn’t.
So how often do things fail? Well things are much more likely to go wrong when any product is either new or reaching the end of its designed life, the first few miles a car experiences show up any glitches in production and then once these are sorted most modern cars will trundle on for over a decade without significant problems (assuming its correctly maintained). During the cars early life car makers measure things in returns per thousand and generally they run well below 5, that’s 0.5% of cars having any sort of fault at all in the first year of ownership. Good models will run at less than 0.005%, and these faults could be anything from a cup holder breaking to an engine failing. The trouble is that if you churn out a couple of million cars a year then even these tiny numbers mean there will be hundreds of failures in the field, unfortunately these make good stories. Manufacturers hate even these small numbers of faults, obviously every company’s dream is to have no failures at all, and indeed some models achieve this, and they are all striving to eradicate all potential for failure. But occasionally I think its a bit sad you will never see a headline reading ‘millions of car turned out to be pretty good actually’.
Even a very high powered Porsche can be safely driven sideways in the rain by an idiot driver, as shown here.

Cars are amazing.
Here’s a challenge for you; think of a machine that has to work in heavy rain, baking sun, snow, ice, deserts, be precise on tarmac yet still cope with cobble stones, Suffer grit and gravel being blasted at it from underneath and do a huge range of complex mechanical tasks at temperatures between -40 to +50 C, last over a decade whilst being shaken, accelerated, decelerated by novice users in a crowded and complex environment.
There are no other machines, just motor vehicles, which have to contend with all this.
But it doesn’t stop there, the engine is retuned every combustion cycle, hundreds of times each second in order to meet the incredibly stringent emissions laws, pollutants are measured in parts per million, the tests are so sensitive that simply exhaling into an emissions test machine would cause the limits to be exceeded (note; these are not the simple emissions testers used at MOT stations, the MOT emissions limits are laughably lax by comparison to the certification tests the manufacturer has to do).
To give you a very rough idea of the amazing computing power needed to control and engine to these limits, a modern engine control box (ECU) may have around 25 thousand variables, tables, maps and functions. It calculates mathematical models of how the air flows through the intake system, how the pistons and valves heat up and how the catalysts is performing, it analyses the subtle acceleration and deceleration of the flywheel every time a cylinder fires, it listens to the noise the cylinder block makes and filters the sound to decide if the engine has the slightest amount of knock (in fact some engine deliberately run the engine into borderline detonation to extract maximum efficiency). It talks to the gearbox to anticipate gear changes and control torque so that the gearbox ECU can precisely control the energy input into the drive line during a gear shift. It analyses the long and short term behaviour of every single sensor and actuator to automatically compensate for ageing and wear as well as diagnosing and compensating for any faults.
But it doesn’t stop there, on some cars the suspension analyses the road and adapts to suit, the auto gearbox monitors the drivers ‘style’ and changes the way it works to please them. The brakes check wheel speed thousands of times a second and deduce when a tyre is about to skid, not when it already has started skidding, and relieve brake pressure just before it happens to ensure the tyre provides maximum grip and stability.
The climate control breathes in cabin air through tiny aspirated temperature sensors and adjusts valves and flaps to discretely meet your comfort needs. The stereo selects a nearby station as you drive along and seamlessly switches in so you never have to retune in order to continue to listen to Radio 2 on long journeys. All sorts of things are controlled and monitored from fuel pumps to light bulbs.
This is the engine and gearbox control from a 20 year old Jaguar, since then it has got a whole lot more complicated!

All in all an average family car might have between five and ten computers working together, sharing information and jointly controlling the car, a typical example would be the ABS unit supplying road speed info to the gearbox so it knows what gear to select. Luxury cars can have over 50 different computers, even the seat heaters have self diagnosing control brains in and talk to the car on a serial bus, and they all interact with things like the battery management systems which may at any time request all these systems change the way they are operating in order to cope with some adverse situation.
The way these systems work together can be very complex, for instance stability control uses the ABS system to apply brakes on individual wheels in order to pull the car to one side as well as requesting a certain wheel torque to ensure the car goes in the desired direction, this torque is controlled by the gearbox and engine working together too, the engine can react almost instantaneously by altering the spark angle (these events happen so fast that the engine has to wait for the airflow to reduce going into each cylinder even though it moves the throttle immediately, because of the air’s inertia!).
Components have to operate faultlessly for millions of cycles, if an engine or drive-line fault develops then the systems must identify it, adjust the mode of operation to minimise risk to car and people, and alert the driver, just like having an expert mechanic on board.
In addition the car has to be comfy by isolating key frequencies from being transmitted by the suspension and engine mounting systems, prevent wind noise from the gale force breeze rushing past the shell, stop the metal box that makes the cabin sounding like a metal box and muffle the many kilowatts of noise running through the exhaust pipe.
It also has to be economical, using every drop of fuel sparingly, compromising the shape of the car itself to reduce drag whilst still allowing enough space to get everything in and have enough air flow round the hot bits to stop them degrading.
But as well as being frugal it also has to perform well, even a modest family hatchback these days has the performance of a race car from the ’60s, indeed there are many saloons with well over 500bhp now, compare this with the 1983 F1 race winning Tyrrell with 530 bhp. Yes our super comfy mobile entertainment centres have the performance of an older Formula 1 car.
And not only does it have to balance all these driving related tasks but it also has to have a really good sound system and have most of the comforts of home, some even have cup holders and fridges.
A few decades ago an Engineer could just look at a car, such as this ultra rare Lagonda V12, and understand how it worked. How times have changed.

Not even the Space Shuttle has to contend with this level of sophistication. I can’t see rockets running catalytic converters and exhaust mufflers any day soon.
And here is the kicker; as well as coping with all that, it also has to perform special functions in a crash. We have multiple air bags, who’s operation is tuned to the ‘type’ of crash detected, we have automatic engine cut, hazard indication, seatbelt pre-tensioning and some cars even ring for help. The structure is designed and tested to ensure it collapses in a controlled manner, the engine design is constrained by pedestrian head impact tests on the bonnet, even the steering wheel is designed to steadfastly hold its position as the cars structure a few feet in front of it is crushed at a rate of up to 15 meters per second.
Name me one other machine that has to detect, reliably, when it is about to be destroyed and then deploy safety mechanisms in a controlled and measured manner during the actual process of its own destruction. You’ll struggle with that one.
Now this feat of engineering would be amazing even with an unlimited budget, but the fact is that cars are made as cheaply as possible, which just take the achievement from amazing to utterly astonishing. In fact you can buy a basic car for the price of a really good telly, that’s bonkers.

Please take a few moments to look at your own car, and marvel. And if one part goes wrong by all means take it back and get it fixed, but do try to be sympathetic to the scale of the problem engineers face.

The road ahead is challenging, but also very exciting as Engineers turn dreams into reality.

Post Script:

Media hype
I noticed something interesting during the Toyota recall, the media could have played a very useful role and helped society, I say ‘could have’ because what they actually did was the complete opposite.
What they could have done is reported actual news, facts presented objectively such as ‘a small numbers of cars may have a fault causing the pedal to be stiff’. That is a fact, it gets the info over simply and effectively, you know what is being said. Simple.
They could have gone further and said something like ‘if your pedal feels stiff visit your dealer, but first check the floor mat hasn’t got stuck under the pedal’. That would be helpful.
But they didn’t do that.
No, what actually got reported was along the lines of ‘mum of five in death plunge tragedy’ and ‘is your car a ticking time bomb of doom?’. Stupid, dramatised gossip that conveys absolutely no useful information.
But of course this scaremongering helps to boost sales of that form of media bilge, so expect more useless crap in the future about every important storey going.
And this is a real problem, not only because it leaves us all badly informed and scared, but because the car companies now know that being honest and open has become the wrong thing to do.
All media has a responsibility, and its time they (we) faced up to it.

Leave a Reply

Your email address will not be published. Required fields are marked *