Engines Haven't Been Fully Mechanical in Decades: Pull One Fuse and It Dies
Pull one fuse on a 1991 Nissan Figaro and the engine dies instantly — the crankshaft won't even turn. The computer controlling combustion is the real heart of this engine; the mechanical parts are just its actuators.
The argument · tap a timestamp to hear it
Pull one fuse and the engine dies
In the Figaro's fuse box there's a fuse dedicated to protecting the line to the ECCS (Electronically Controlled Combustion System). The host pulls it out on camera, and the running engine immediately dies — and afterward the crankshaft won't even turn. This isn't a computer 'monitoring' the engine and fine-tuning injection to meet emissions standards — it's directly controlling each cylinder's fuel injection and spark plug firing. Without this computer awake, the engine is a lump of scrap metal. This directly refutes the complaint that 'only modern cars have been invaded by computers': electronic control of engine functions has been the norm for decades.
Distributor points burn through 5 million cycles in 5000 miles
The points in an old distributor make and break the ignition coil circuit. Cruising at 2000 rpm, with a four-cylinder engine firing twice per revolution, 5000 miles of highway driving means those points open and close about 5 million times. They wear, and as they wear the ignition timing starts to drift — which is why old cars need regular tune-ups: not just an oil change, but cleaning or replacing the points and resetting the timing. Timing was never something you 'set and forget.'
The higher the rpm, the earlier the spark plug must fire
This is problem five: the engine doesn't want the spark plug to fire at a fixed angle before top dead center. The faster the engine spins, the earlier the spark plug should fire. In the Ford Model T era, the driver manually adjusted the timing advance lever, which nobody liked, so vacuum advance and centrifugal advance mechanisms inside the distributor evolved. But that also meant the distributor had variable timing; during a tune-up you only set the base timing. Once the advance mechanism fails, even with new points and perfect base timing, the engine still won't run right under acceleration.
A base model car is just missing a few buttons on the steering wheel
Electronic throttle makes any car that uses it inherently capable of cruise control, whether or not you paid for the feature. The host gives the example of this Nissan Cube: the entry-level version didn't come with cruise control, and all that was missing were the buttons on the steering wheel. Swap the base steering wheel for one with cruise buttons, and congratulations, you now have cruise control. Behind this is the electronic throttle completely decoupling the accelerator pedal from the throttle plate — the pedal is just a few sensors, and the computer interprets it as a 'request for power,' then decides how to open the throttle itself.
You can count cylinders by listening to the starter
When the engine computer powers up, it doesn't know where the camshaft stopped — it might be between encoder teeth, creating ambiguity. So it must see the complete encoded sequence, meaning the camshaft must rotate a full turn, before it dares to inject fuel and fire. And each cylinder experiences one compression stroke per camshaft revolution, and compression noticeably slows the starter. So in most cars, on a cold start, you'll hear the starter stumble once per cylinder; count the stumbles and you'll likely get the cylinder count. The Figaro is an exception: its encoder has finer resolution and can resolve partial rotation, so it fires almost as soon as you touch the key.
Pull the crankshaft position sensor and the car still drives
The host pulls the crankshaft position sensor on the spot, and the car still starts and drives, just with a longer crank time. The reason is that the crankshaft encoder itself doesn't encode information — it's just two sets of evenly spaced teeth with two gaps 180 degrees apart, mainly used to identify top dead center and give the computer a sanity check. What actually controls the engine is the camshaft position sensor. The crankshaft sensor's main job is fault detection: the fine teeth let the computer sense extremely subtle speed changes, and each power stroke slightly accelerates the crankshaft. If cylinder four should have fired but the expected acceleration isn't seen, it's logged as a misfire on cylinder four.
Too many misfires will burn out the catalytic converter
Random misfires get logged by the computer. If the same cylinder misfires repeatedly and exceeds a preset threshold, the computer sets a misfire fault code and lights the check engine light; if the misfires are severe, the light starts flashing. The flashing is to get your attention, because continuous misfiring is one of the fastest ways to destroy a three-way catalytic converter — unburned fuel entering the converter makes it very, very hot, and various additives in the fuel erode the precious metals inside.
The software was finished before the car was sold
The host offers a comment on today's car market: Nissan (and Hitachi) had all this software figured out before they sold the car. They spent a lot of time programming the engine control module, doing extensive testing, and then declared it ready for production. The host marvels: imagine actually finishing the software and declaring it done — we used to do that. This 2010 economy manual-transmission car has to, within about a second of the computer powering up, control four coils, four injectors, and the electronic throttle to start the engine, then continuously monitor more sensors, adjust fuel trims, and achieve stoichiometric air-fuel ratio.
In their own words · checked verbatim
That computer isn't, like, monitoring the engine and tinkering with fuel mixtures to meet some emission standards. It is in fact actively controlling both the injection of fuel into each cylinder and the firing of the spark plugs. Without that computer awake and functioning, this engine will not run.
5,000 miles of highway driving between tune ups means the engine will have been running for over 80 hours, and with two ignition events happening with each rotation of a four cylinder engine, at 2,000 rpm that switch is going to open and trigger the ignition coil some 5 million times.
In many cases, an entry level car which didn't come with cruise control oh, like this Nissan Cube, for example, is only missing the buttons on the steering wheel which activate it. And if you were to swap the base model steering wheel for one with the cruise control buttons, congratulations, you now have cruise control.
when you start most car engines, you'll hear the starter motor slow down once for each cylinder the engine has, and then, since the computer is now certain it knows what it's looking at, It fires the fuel injector for the cylinder that's currently in the intake stroke, fires the spark plug just after that, and the engine roars to life.
Nissan (and Hitachi) figured all the software out for this thing before they sold the car! They spent a lot of time and effort on the programing for these engine control modules, and did a lot of testing so they could declare it good to go. Imagine that, actually finishing software and declaring it done!
I truly don't know how you can convince yourself that engines are simple, but electric motors are complicated.
Figures
| Figaro engine displacement | 987 cc four-cylinder | 2:00 |
| Figaro horsepower | 74 hp | 6:03 |
| Figaro model year | 1991 | 1:00 |
| Four-cylinder firing order | 1, 3, 4, 2 | 10:07 |
| Figaro base ignition timing | 15 degrees before top dead center | 23:29 |
| Fault conditions detectable by this engine control module | over 100 | 44:15 |
Glossary
- ECCS / Electronically Controlled Combustion System
- Nissan's name for the engine computer's control of combustion.
- distributor
- A rotating switch in older gasoline engines that distributes high voltage from a single ignition coil to each spark plug in sequence.
- points
- A pair of normally closed electrical contacts inside the distributor that open and close to trigger the ignition coil discharge.
- coil pack
- A small resin-encapsulated ignition coil for each spark plug, directly controlled by the computer, replacing the distributor.
- Hall effect sensor
- A non-contact position sensor that senses encoder teeth on the camshaft/crankshaft and outputs a square wave signal.
- stoichiometric combustion
- The state where fuel and air burn completely at the chemically correct ratio; the computer continuously adjusts fuel trim to approach it.
How to listen
Engineers and product people who want to understand how 'software eating mechanics' concretely happened in cars; readers interested in old cars, engine control, and embedded systems.
The segment after 47:00 about hybrids and the grid is more opinion output and can be skipped.