Questions and Answers

WHY Heat The Throttle Body!? Q. This is just a question in general more or less. I would greatly appreciate it if you could answer it for me, and email me with the answer. I've got a 1998 Hyundai Elantra (doesn't really matter), my question is, WHY WHY WHY is the throttle body heated!?

I mean, to me it just doesn't make any sense! There are coolant lines running to the throttle body. I'm pretty sure it's like this on all cars because my parent's van is the same way. Why would I want to heat the air going into my engine? I mean, making it cooler would make a lot of sense, but warmer doesn't at all... I'm baffled... Really...

Your reply is greatly appreciated,
Corey

A. Since the first engine sucked in air, intake air has been heated to some extent. Remember on cars equipped with carburetors there was a large tube that connected to the air cleaner? Well the other end of that hose was connected to a heat collector around the exhaust manifold. This is how warm air got to the carburetor.

There's two reasons we want to heat the incoming air. The first is that the atomized fuel will mix with warm air better than cold air. This was actually more important with carburetted engines rather than fuel injected engines.

The second reason is to keep the throttle chamber from freezing. Yep, that's right. I said freezing. As in ice forming inside the throttle chamber.

Anyone who lives where it gets cold in the winter has heard of "wind chill". It'll be 30° with a wind chill of 10°. As the air moves through the throttle body, the same wind chill affects the inside if the throttle body. Under certain conditions, such as high humidity, condensation will form inside the throttle body and the moving air will freeze it. This ice will keep building up until it chokes off the air supply and the engine dies.

By running hot coolant through passages in the throttle body, it keeps the throttle body warm and prevents this ice from building up.

Some early fuel injected engines did not have heated throttle bodies and ice formation was such a problem that heated throttle bodies were retro fitted at the dealerships.