Join Date: Jul 2009
Location: Northern Colorado
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The reason this is done is because the fittings leak where they go into the throttle body. I had this exact thing on my DI and when I connected them back to their appropriate positions I couldn't get the leaks to stop (in fact they're leaking on my DII, but not very badly). I removed the intake chamber and tried to rebuild the fittings, but they wouldn't seal for very long. The problem is the fittings are brass? and they're mated into aluminum which has a very different coefficient of thermal expansion...as the engine goes through its normal daily heat cycles, the aluminum eventually breaks the fittings free no matter what method I tried to attach them together.
The purpose of the coolant flowing through the throttle body is to allow the engine rpm to drop once the engine reaches operating temperature. There's an air valve with a heat-activated spring behind it which opens up when it gets warm. With it bypassed, I had to turn the idle way down on my engine.
2003 DII SE7, Front D/S rebuilt, 8mm Kingsbourne plug wires, 92K miles
1994 DI, 130K miles (sold, but still loved)