The heating of the TB is to keep it from freezing. If the TB freezes while driving you then lose all control of throttle position and coming to a stop would not be easy without shuting the motor off or puting the trans in neutral - it's a safety thing. But, this also heats up the air entering the plenum, so yes it does rob power. I removed the feature on my van. My Pontiac car has nothing to heat the TB beyond underhood heat and that has been good enough to prevent freezing.
"it preheats the throttle body to better warm the air to make the engine more efficient when it is cold."
^^^If the engine is "cold", then how hot is the coolant going to be?
And A_G, I don't see how circulating coolant through the TB get the motor to operating temp quicker. So the air is warmer, but that has little to do with the operating temp. Also, the coolant that goes through the TB isn't even going to be warm untill the motor is at operating temp anyways.
It may have some emissions and heat up benefits as well, I have never heard that though, and at this time I don't understand how it would help in those areas. Why would they have a "cold air intake" from the factory if they wanted to warm the air at the TB for emissions? I can understand warming the TB as bandaid engineering for "safety reasons" just to cover themselves for potenial law suits.
On my 5.0 stang the coolant only flows in the egr spacer, which would heat the tb up, so untill the engine is warm the TB is cold. It doesnt get super cold here but cold enough. I have since done the same as ECO and removed it. Was more of a pain to keep it then remove it when I put the Edelbrock intake on. Truck doesnt leak and runs fine so im not messin with it. If your is a pain remove it.
I think it depends on where you live. Mine doesn't even work. I took the throttle body off last year to clean it and the hoses were filled with dirt and cobwebs. They hadn't seen coolant in forever.
If it's a temperature related thing, then why don't the 4.9L's have the same setup?
Can I get a definitive answer as to whether or not this feature is robbing horsepower? Seems to me that common sense points to YES. Brad and I have been bantering back and forth about this and for the life of us, we can't figure out WHY my truck needs it. He had a look at his 06 Mustang 4.6L and it doesn't appear to have any coolant lines going to the throttle body, so why does mine need it?
Thanks Ryan. Did a little searching around google and it seems pretty unanimous across makes and models of cars that bypassing this coolant through the throttle body leads to performance gains. I'll be installing a valve on the intake line next weekend so I can still open up the line if I want to later. I'll keep ya'll posted.
I finally removed the coolant line to the throttle body today and capped the connections. Haven't driven the truck yet and I'm not sure I'll really notice any performance gains... Just figured I'd let ya'll know