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With enough time and skill sets, could a modern car be modded enough to work without microprocessors?

Having machining skills and a fitted workshop, without buying a new motor block or transmission. Through modding of its parts or machining new ones. Discrete electronics could be used (to build multibrivators and control some logic or power output stages) but no microprocessors or very integrated systems.

Lets say an EMP destroyed all microelectronics in a community and people have already depleted the stock and spare parts of old cars.

  • Wouldn't be so modern, would it? You could do it, but you would have to replace most of the engine compartment and you would eventually end up with an early 80s carb gas guzzler. – I have no idea what I'm doing Feb 17 '16 at 9:13
  • I think it is possible to work out a circuit to control the fuel injection and manage the plugs using relays and transistor. – karani Apr 8 '18 at 9:01
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Yes, it is possible

Albeit with some trade-offs.

A modern-day road car is an amalgamation of several sub-systems, and electronics usually have an important role to play in them. The nice thing is that many of these sub-systems were present long before modern-day electronics became commonplace:

  • Engine

    The heart of the beast remains mechanical to this day, but supporting systems like fuel delivery and spark may need to be addressed:

    • Replace electronic fuel injection with carburetor(s) or K-Jetronic fuel injection for a fully mechanical fuel delivery solution.
    • Replace any spark plug coils with a mechanical distributor.

    Note that swapping out an EFI setup for a mechanical solution could leave several sensors redundant, such as MAF, MAP, knock sensors, lambda sensors, CPS, CKPS...

  • Transmission

    Most manual transmissions should be fine as the shift logic is embedded in the driver's cranium, but even automatic transmissions that rely on mechanical linkages rather than shift solenoids could be deployed.

  • Battery/Alternator

    The energy source for alternators will not change (rotating engine). Loss of electronics would imply the loss of voltage regulation, although I imagine that an equivalent voltage regulation function could be enacted with simple electrical components.

  • Throttle

    Many cars today take advantage of electronic throttle control (drive-by-wire), which can be swapped out for a more traditional cable-operated equivalent.

  • Braking

    The brakes themselves are mechanical/hydraulic in nature, but you would lose ABS and traction control functionalities if the electronic "brain" behind the ABS module ceases to function.

  • Drivetrain

    Some vehicles make use of electronics to control the amount of torque sent to each wheels via the differential. This could easily be replaced with a mechanical diff.


These are a few of the key sub-systems involved in a motor vehicle. There are many more ways in which existing electronics could be replaced, each with varying degrees of functionality retention.

  • 1
    Your two points under engine sound deceptively simple, but they would both require machining of very complex parts. – JPhi1618 Feb 17 '16 at 13:34
  • I'm sorry if I'm way of the mark since I'm not very well versed in car's mechanics (I'm an electronics engineer), but isn't there's some relation between the cam position and the spark plugs timing? With some markers (and discrete/power electronics magic) one could activate the spark plugs coils as they are, right? – Sdlion Feb 20 '16 at 1:52
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There is such a beast known as an analog computer. The computer uses OpAmps to implement complex formulas in an entirely analog fashion. The formulas implemented take input from things like mas air flow, air temperature, coolant temperature, engine rpm and provide output to the fuel injectors.

With enough time most if not all systems in a car could be replaced with analog computers without having to resort to converting the systems to all mechanical.

These kinds of computers are not used in vehicles because they are very temperamental and do not have any kind of redundancy. To change the proverbial program discrete components need replaced in the computer. The computer is temperature sensitive because things like resistors change their value slightly with temperature. If an erroneous reading is taken in by the computer from a malfunctioning sensor it has no way of rationalizing that there is a malfunction.

  • @sdlion PS with the kind of shielding that is in modern vehicles to protect them against outside EM interference and to protect them against the EM noise made by the ignition system it is doubtful that the main engine computer would be fried by an EMP. – vini_i Feb 17 '16 at 12:42
  • The EMP is just an stage context where this would be necessary, one could imagine living in a deprived country where spare parts would be hard to find and some parts of the vehicle began to fail. – Sdlion Feb 20 '16 at 1:43
  • I'm not sure if it would be ok to add OpAmps since at that integration scale we could add discrete logic chips (which with the help of some analog chips they'd be better to control the logic than an analog computer). Rather than recreating the ECUs functionality, I was more interested in which practical ways could exist to replace the different ECUs in a car. – Sdlion Feb 20 '16 at 1:47
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Best solution seems an amalgam of the suggestions. Jetronic fuel injection. Sensors on the camshaft to fire (amplified) an ignition coil and regulation of the alternater was previously done by a power tranistor effortlessly. Only mechanical problem is making or modifying a manifold for the jetronic air intake

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