IN ORDER FOR YOUR ENGINE TO RUN EFFICIENTLY THE COMPUTER MUST RECOGNIZE A CONSTANT OPERATING TEMPERATURE

REMOVING THE THERMOSTAT MIGHT KEEP THE ENGINE "TOO COOL"---THE COMPUTER MIGHT REMAIN IN "CLOSED LOOP"

THIS IS SORTA A QUICK EXPLANATION OF THE LOOPS

THERE ARE TWO "LOOPS"---"OPEN" AND "CLOSED"

OPEN MEANS THE SENSORS ARE GIVING THE COMPUTER "REAL TIME" INFO, EXAMPLE: O2 SENSOR IS TELLING THE COMPUTER THE OXYGEN CONTENT IN THE EXHAUST SO IT CAN ADJUST THE INJECTORS TO GET THE MOST EFFICIENT "BURN" POSSIBLE

BEING THAT IT TAKES A LITTLE WHILE FOR THE O2 TO WARM UP TO "TRANSMIT" INFO...HOW DOES THE ENGINE RUN?

SAME GOES FOR "TEMPERATURE SENSORS---IT MUST GET TO OPERATING TEMPERATURE BEFORE IT IS "SENSED" BY THE COMPUTER

THE ENGINE RUNS "CLOSED LOOP" DURING THE TIME IT AWAITS FOR SENSOR TO "COME ON LINE"---WHICH MEANS THE COMPUTER HAS "PRESET" VALUES PROGRAMMED INTO IT--IT RUNS OFF OF THEM, UNTIL ALL SENSORS COME ON-LINE.....CLOSED LOOP SORTA MEANS, THE ENGINE COMPONENTS ARE "FED FALSE INFO", THAT WILL MAKE THE ENGINE RUN---THIS "LOOP" IS NOT EFFICIENT, USUALLY YOU WILL NOTICE IT RUNS RICH--MPG GOES DOWN!

THIS IS NOT ONLY TRUE FOR THE O2 SENSORS, BUT OTHER SENSORS NOT WORKING WILL CAUSE THIS (STAYING IN CLOSED LOOP)---CLOSED LOOP IS BASICALLY "DEFAULT"

"OPEN LOOP" IS WHEN THE COMPUTER RUNS THE ENGINE OFF OF "RIGHT NOW!"--"REAL TIME" INFORMATION----BASICALLY THE PRESENT ENVIRONMENT IS BEING SENSED BY THE COMPUTER---BAROMETRIC PRESSURE/ OXYGEN CONTENT IN THE FUEL/ ENGINE TEMPERATURE/ AIR MOVEMENT INTO THE ENGINE/ ETC...ETC. WITH THIS INFO, THE COMPUTER DOES NOT RELY ON "PRESET/ DEFAULT" INFORMATION TO MAKE INEFFICIENT "FUEL DECISIONS"----IT CAN NOW USE THE "PRESENT ENVIRONMENTAL INFO" TO MAKE EFFICIENT FUEL DECISIONS GIVING YOUR VEHICLE PEAK PERFORMANCE

THE MEDIC

Answered by CJ MEDEVAC (expert)
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