Originally posted by DennyW
Absolutely Mike. They have them run a little on the rich side anyway. And by running it lower, he's even richer, and that wouldn't bring on the check engine light, it would just run cold. The coolant sensor over rides the oxygen sensor, cause before it goes to closed loop, that is the main sensor for control also.
yep, and with a 180 t-stat it wont ever go into closed loop. if the temp gauge is in the head and the computer temp sending sensor is in the intake then the water in the intake might not be 195 degrees, and the water temp. is the only way the computer has to know when the motor is warm. i had a mech. one time put a rebuilt motor in a late modal ford truck, and the only t-stat he had was a 180 degree one so he put that one in and we worked on that motor for a mo. trying to find out why it ran rich, until he told someone he had put a 180 t-stat in, so we put the right one in and that's all it needed. I wont forget that for a long time.