Understanding how cars work by looking at the internal engine sensors

At HDDG22, Rick Altherr talks about tinkering with car engines and understanding the sensors and ECUs on board

Supplyframe’s mission is to create more access to information about electronics design and manufacturing. As such, we do a meetup in San Francisco called, Hardware Developers Didactic Galactic. These events include talks by industry experts in hardware and software. The speakers are often building hardware for recreation or as part of their employment. The common thread is that they want to give a view “under the hood”.

HDDG22 was held June 29th, 2017 at the Supplyframe San Francisco office. We welcomed Rick Altherr (@kc8apf), software engineer and car enthusiast. This talk focused on the range of sensors that exist inside of a car, the number of which has increased dramatically in recent years. Electronics in general have increased their prevalence in percentage of the Bill of Material cost of a car. A recent report stated that the new average cost of electronics inside a vehicle could reach $6,000 per car.

View the slides:

A range of sensors

The sensors themselves were discussed in the context of optimizing high performance of cars. This placed the focus on things like the fuel/air mixture and finding optimal points of operation. Some of the sensors and modules and sensors discussed included:

  • ECUs (Electronic/Engine Control Unit)
  • PCM (Powertrain Control Module)
  • TPS (Throttle Position Sensor)
  • MAP (Manifold Air Pressure)
  • MAF (Mass Air Flow)
  • Oxygen (Lambda) Sensors
  • Crank Position Sensors
  • Cam Position Sensors
  • Knock Sensor
  • Air Temperature
  • Coolant Temperature
  • Oil Pressure
  • Boost Control
  • Idle Control
  • Vehicle Speed
  • Gear Indicator

Through the use of things like Fuel Maps. This is the measurement of the air and fuel, comparing it to things like speed or power delivery and looking at where there are maxima and minima. This process is done experimentally, as this is the only practical way to find Volumetric Efficiency (VE). From here the engine is tuned to deliver different amounts of fuel or air at higher speeds or higher torque (lower speeds).

What about other types of cars?

This practice was based around gasoline or ethonol based engines. The operation of diesel engines is different enough that many of the sensors and methods described do not apply (for instance, diesel operates without air injection).

Though the prevalence of gasoline based engines will drop in the coming years as electric vehicles become more prevalent, there has never been a better time to optimize a fuel based engine. Not only enthusiasts like Rick, but also for car companies looking to increase engine efficiency and balance that with power delivery. Engineers will be able to more finely tune engines to fit the need of drivers.

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