Join Date: Dec 2001
Location: Belleville, Illinois
Thanked 22 Times in 17 Posts
Re: heater question
The purpose is to warm the intake manifold as quickly as possible after a cold startup. It is to vaporize the gasoline better, for emissions reduction and better running during warmup. Those setups usually have a thermostat in the loop somewhere, possibly switching a vacuum line that operates a water valve.
Other engines use a flap in the exhaust manifold that directs the exhaust under the carb until a bi-metal spring gets hot, moves the flap, and bypasses the flow straight out the pipe.
As emission rules becape more stringent, they went to the electric heater, because it can go to work immediately instead of waiting for hot water or hot exhaust.
If it's functioning properly it has no bad effects. If the thermostat sticks open, it can theoretically get the intake manifold too hot and reduce power slightly.