Digital gasoline injection was a massive leap forward for motor handle. Having said that, early implementations frequently left anything to be desired. This was the situation for [Rob] and his Porsche 944, which had relied on an aged-fashioned mechanical air stream meter (AFM). He determined to substitute this with a present day mass air flow (MAF) sensor rather, and documented the process online.
AFMs are normally a target for substitute on old cars. They are typically based mostly on a flap that moves a potentiometer wiper throughout a carbon trace which wears out more than the many years. They can also existing an air stream restriction in some cases, limiting functionality. MAF sensors as an alternative evaluate the volume of air flowing by way of with a warm wire. The total of present expected to manage the temperature of the wire signifies the quantity of air flowing via the sensor. They’re less restrictive and easily available as they’re used in a lot of cars and trucks nowadays.
To operate a MAF in spot of the AFM requires a circuit to emulate the AFM’s output. [Rob] utilized a STM32 Cortex-M0 to study the MAF, and then output the pertinent voltage to the Porsche’s engine personal computer through PWM and a very low move filter. To figure out how to map the MAF’s output to match the AFM, [Rob] built a rig to blow air by way of equally devices in collection, and measuring their output on an oscilloscope. This information was employed to software the STM32 to output the ideal emulated AFM voltage for the provided MAF signal.
It’s a excellent piece of operate from [Rob] that has his Porsche operating fortunately on new pieces. We have viewed equivalent hacks completed to other cars and trucks ahead of, as perfectly! Video soon after the split.