IAC and throttlebody question.

[oxbrain]

How much is the IAC needed? In the name of simplifying my vacum and coolant lines, I would like to just bypass or remove it. From what I understand, this would only affect my idle when cold, and would have no effect once the engine warms up. Is this true, and how bad would the idle be? Do I still need to have the IAC plugged in, or can I remove it and let the connector hang?

Also, the coolant lines run into the throttlebody. Why is this and do they need to? The capri fuel rail is much larger, and the coolant lines would be a real tight squeeze. I am thinking of just bypassing the throttlebody.

Overall, instead of routing from the heatercore pipe -> throttlebody -> IAC -> intake manifold, I would run it heatercore pipe -> intake manifold.

[festivaWES]

I think that once warmed up the idle will most probably be irratic. It may not even idle at all without it plugged in. I don't know i never tried, but I would save your self the hassel and leave it in there.

[festivaWES]

The coolant lines that run to the throttle body are there for the simple fact of keeping it above freezing level in cold climate areas so the butterfly won't contract thus binding up. I been a case to where the get stuck a full throttle..... I would bypass the throttle body coolant lines if you A: dont live in a area where it snows or get colder than freezing point. Or B: you only drive the vehicle during the summer months.... Don't get me wrong it's a good mod to lower your intake temperature, but no suitable for everyone.

I have no coolant lines anywhere on the throttle body, and i dont have a heater core either..

[oxbrain]

We've had a harsh winter, but otherwise it doesn't get below freezing more than a day or two per year. If the butterfly would be binding, wouldn't it still do that when the engine is cold?

[festivaWES]

when metal only contracts thousands of an inch and aluminum probably contracts more than the butterfly. But the coolnat keep them from concracting......I'm just saying it "could" happen.

[mattswabb]

The car will run. On the BP car I was doing some work last summer and disconnected the IAC and TPS plugs and missed plugging them back in. The car ran but not well at all. I went straight home and found the problem.

[monkeyracing]

IAC: absolutely necessary on a FI car. This is the thing that controls you idle, whether it's hot, cold or in between.

The coolant lines running through the throttle body are there to prevent icing. Air or fuel expanding rapidly, or under a vacuum will create cold. On carbed cars, this would freeze up the carburetor. On fuel injected cars, it's more about drivability. Icing can occur even in warmer climates. It's not as much of a problem as it used to be, considering FIs advantages.

[WBBulldogs]

This topic just gave me an answer to my topic on my car getting the throttle stuck. It's cold here often when I drive and when I was accelerating from like 55 to 75 then slowing after a couple minutes at my exit the throttle seemed stuck. Could my butterfly be stuck somehow? Would the butterfly be closed or open? Here's my topic:

http://www.fordfestiva.com/forum/viewtopic.php?t=9817

[oxbrain]

I decided to bypass the throttlebody, but plumb in the IAC. I'll re-route my vacum lines later when I make a new intake, but for now it will just look ugly.