Can someone please let me know at what temp does the car enter closed loop fueling. need to change a faulty thermostat and im wondering if I can go down a bit on the temp ratings for summer.

 

Mine enters closed loop at about 150ºF

Cheers
DD

 

I would be interested in that as well let us know how you go

 

Sorry for the long wait but here are my findings. I replaced the stock thermostat with one with a 174 F rating and my car was just not agreeable with the lower rated thermostat. It ran a bit sluggish and it would stall in the morning while warming up at idle. Once it ran a bit during the hot 100 F temps it would be fine. Went back to OEM 195 F Thermostat and no more stalling during morning warm ups. There is a 180 F available but it just may be a waste of time. I should have taken a look at the fuel trims with the different thermostats in place because the smog pump would kick in more frequent than usual even after a long drive at 100 F weather. I think I will try insulating the sc intercooler and see if intake temps come down a bit.

 

JJ- What are you trying to accomplish running the engine cooler? The thermal efficiency of the engine is higher at higher temps, and these Jags don't have any sort of cooling issues. And, yes, running an engine too hot is bad for the parts, but running one cool has its own set of anomolies, like sludging and acid build up in the crankcase.
This is a good place for the old "if it ain't broke, don't fix it till it is"