I have an EF, and am running a 192F (farenheit?) thermostat in at the moment, and it cycles 85-90 in diagnostic mode.

Some guys I know say the ideal is for it to cycle between 95-100, so that it'll get out of warm up mode, & improve fuel economy.

Does anyone know the temp that warm up mode stops on an ef i6???

I got the current thermostat from coventry auto, & they chose it as the "recommended" temp for the EF.

I don't want to start swapping things if I don't have to.
I would have thought 85-90 was ok, running halway on AL of normal on the guage.

Anyone?

Well there's cold start mode and there's also fuel enrichment based on temperature.

Cold start mode sees the oxygen sensor ignored (because it doesnt work until its up to temp). i.e. you're running in open loop mode. This stops after about 30 - 60 seconds of driving tho.

Fuel enrichment occurs at all temperatures... its basically a function of the fuel injection formula...

i.e. this much air @ this coolant temp (plus a whole bunch of other things) = xx miliseconds the injector needs to be open.

If you're getting a readout on the guage, dont worry... the car is not in cold start mode.

ok, that is helpful info, thanks.

Does this mean the 192F thermostat is spot on, or should it run hotter to squeeze a bit more economy via the fuel injection formula you state?

Hmmm... well to be honest ive always placed more value in having a cool engine as opposed to having one that uses less fuel.

If you dont have concerns about the temp reached then i guess technically yeah, you would gain some fuel economy by running the next higher thermostat.

I think the 192s are used in taxis etc that spend a bit of time sitting around?

Thanks.
If taxis are running them then there can't be that much to gain by going a little hotter, or they'd be doing it I think.
Cheers

i would have said 95-100 would have been a tad hot...

The fully open temp of a standard I6 thermostat is 92 deg. When using them, you car should run at between 93 and 95deg as a normal operating temp.

If its fluctuating a little it could be your thermostat is getting a little old or the temp sensor is not as good as it once was. When I changed my temp sensor, I got a more reliable and accurate gauge, as well as more power and better fuel economy.