A Precision Pressure-Source System for EFI-Control-Unit Calibration and Test

Simulating manifold absolute pressure for the calibration and test of domestic Electronic Fuel Injection (EFI) controls demanded an absolute-pressure-source-system stability, accuracy, and speed of response not previously required for automotive-component manufacture. A 36-point pressure source having a root-mean-square stability of ±0.002 pound per square inch (±13 pascals) absolute, an accuracy of better than ±0.002 pound per square inch (±13 pascals) absolute, and a response time of 500 milliseconds into a 1-cubic-inch (16-cubic-centimeter) switched volume was developed to meet this need. Source-system design drew heavily on aircraft flight-line-check-out test-equipment experience. The system is used for 100 percent production calibration and test of EFI Electronic Control Units.