Closed Loop mode
 

will having the thermo sensor on the back on the waterpump disconected send the ECU into a closed loop mode? and what will it do if it is in closed loop mode? will it just not run as well. will there be a noticable difference in power? I'm wondering today becuase i went to the dyno and am a bit disapointed, i only pulled 154.2 hp and 125.7tq with a fresh rebuild and streetport, rb collected header, custom header back, s5 internals, s5 upper intake mani (vdi) tb mod, hks intake. I feel liek that's really weak. anyways will the thermo sensor make that much of a difference? thanks, any info would be great! thanks
Dom

bump

Closed loop is used with the O2 sensor to conserve fuel at cruising speeds. The thermosensor is used to determine what temp the engines at, and it'll default to a cetain temp if unplugged, which would make the car not run as good if it's not at that temp.

The temp sensor has to be connected for the engine to run right. With it disconnected the ECU stays in open loop mode and runs an overly rich fuel map as it would in a cold engine at startup. Once the engine is up to temp the switch sends a signal to the ECU that it's ok to use open loop mode (at mid range RPMs).

-jb

No. The only time closed-loop is used in under light-load, steady-speed conditions. It will never occur during a dyno power run.