I read this on the other forum this afternoon. I found the part here (http://www.romaniatoyotaparts.com/v6thertrd4ru.html) last week and didn't think too much about it. I mean it's just a thermostat. The quote below is taken from a thread on the other forum

"A 160 deg thermo will also have another effect on your engine. It will increase the performance. This is due to the engine running cooler, the computer will pump more fuel into the cylinders giving a richer mixture becuase it sees the cold condition. The downside is you will lose some MPG.

Most chips sold for mustangs, cameros, etc, come with a 160deg thermo also. I don't think the chips do a whole hell of alot. It is the 160deg thermo and your stock computer pumping more fuel which is giving the performance."

Truth or BS?

Later.

Matt

 

You're in luck because somebody just asked this question in the sept issue of petersons 4wheel.

Quote:
A lower temperature thermostat alone might make a fuel injected engine produce more power by fooling the engine's computer into making it run rich all the time. You're better off getting a chip or programmer that advances your engines ignition timing and adds more fuel at wider open throttle, and then just uses the low temp thermostat to keep detonation to a minimum. A low temp thermostat alone will dump more fuel into the engine across the board in a sloppy attempt to make more power.

This fuel inrichment via the t-stat is made possible because a factory EFI system is designed to inject more fuel into a cold engine, instead of using a choke to restrict air like a carburetor would to aid engine warm up. It all sounds good at first, and the price is right, but we don't think it's a great idea. By making the engine run 20-30 degrees cooler than it was designed to, you trick the engine's computer into thinking it is always in warm up mode, so it ignores the oxygen sensor signal and may not go into closed loop mode. Goodbye fuel economy! Yes, a reduction in engine temp will result in lower combustion camber temp, and will reduce the chances of detonation but only because the computer will be over fueling the engine. Bottom line-save your money for the chip first."

Steve

 

if you run your engine too cold, it's not good for it at all. the engine needs at least some heat to function properly/make power. how much? i don't know. i'm just telling you what i heard. the idea of a cooler t-stat has merit. i did something similar to that by using an electric fan with an adjustable t-stat that acts like a variable resistor. i've got it set so that my engine will run a little cooler than with the stock fan. as time went by, i noticed it began to run a little richer (i could smell the fumes out of the exhaust). i noticed from that point on my engine seemed more responsive at the throttle. i remember thinking "man, i hope this isnt the computer getting confused again, then resetting itself back to stock config, making me lose my power". luckily it never did. my mpg went down a little i guess. i can still squeeze about 300 miles to a tank. just another option. i'm skeptical about getting that chip. i'd rather put it in myself so i know it's there, plus i'd have to do a dyno before and after for proof that it works. as if the chip isnt expensive enough. i'm currently debating on which mod i should do first... bored out throttle body, the chip, or a Venom 400 module (works like a chip, but is external and just plugs into your computer). i'm leaning most towards the bored out TB. more air is good air