1981, First Closed Loop Exhaust Sensing Digital Engine Control (Carburetion)
This was the first application of a microprocessor programmed closed loop air/fuel controlled carburetor. The digital computer system monitored the input from an exhaust mounted oxygen sensor and adjusted the air/fuel ratio so as to enable the efficient performance of an emission lowering, oxidizing and reducing, exhaust catalytic converter.
At this time, it was a monumental undertaking and big risk to the company. GM was going to put a large portion of its car volume into production relying on this new microprocessor technology. It was the way to meet the increasingly stringent emissions standards of the day. Long term experience did not exist for the electronics hardware. Infant mortality of electronic components was a known problem, so a 24 hour burn-in test was done in a temperature varying environmental chamber for each computer. Even though the defense and aerospace industries were the major customers of electronic components at that time, their requirements for reliability were not sufficient to meet the needs of the automotive industry due the multiplier of millions of units for automotive annually. Therefore, a major electronics industry effort was launched by GM to meet the need to improve component reliability by orders of magnitude. Full volume, 24 hour burn-ins could not be continued over the long term.
GM’s Engine Emissions Control Center coordinated the system development for the car divisions and received direct support for production from many of the component divisions: AC Spark Plug (exhaust sensor, converter), Rochester Products (carburetor), Delco Electronics (computer), Delco Remy (solenoid), Packard Electric (wiring, connectors) and Delco Products (actuators).
Note: A story, dating back to 1971, has it that time was so compressed to get the first under-floor catalytic converters into production that bulldozers were brought in to clear out a large design office area. They pushed all of the office partitions and furniture out the back door of the Oak Creek, Milwaukee plant, so the presses could be more quickly installed and the lines for start of production, SOP.
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