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Old 04-23-2010, 04:36 PM   #1
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Default IAC leak normal?

Is it normal for the IAC to pull vac:
1. when it's unplugged electrically?
2. when you are substantially off idle, like 3000 rpm?

If it is normal, wouldn't this constitute a good-sized boost leak?
If it's not normal, any way to fix/unstick it?

IAC from a '97.
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Old 04-25-2010, 11:41 AM   #2
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Bump. I'm thinking the IAC could "leak" if the water ports are not hooked up? Always cold=always trying to draw a smidge more air for high idle speed. I'm going to test it in my kitchen. If this is the case, can the valve be taken apart to wedge the hot water pill side closed to only work idle air with the actual electrical IAC valve? I really don't want to hook those water lines up. I have a tidy friggin plumbing setup now that I don't want to disrupt and I don't mind working strictly with warmup enrichments and idle valve settings.
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Old 04-26-2010, 11:36 PM   #3
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Ok smart guys. 97 IAC consists of two parts. One is the electrical valve (stepper motor?) that works on command from the ECU. The other part, connected through the same inlet passages and nipple, but independently operating, is a very simple thermostatically controlled plunger. The thermostat is in the cavity fed by the two hose barbs on the bottom of the IAC/throttle body. When cold, this plunger opens the inlet passage to let in a little air to give you a higher idle. When the water in the cavity reaches (according to the Rod's book) 104*F, or a temp easily attainable by the kitchen faucet, it closes and doesn't let air in through this channel through the IAC inlet nipple.

If you are not running hoses to the throttle body and you are not routing the IAC inlet to the intake stream, if you didn't plug the thermostatically controlled portion of the IAC you have a vac/boost leak.

I'm tapping them for 1/8 NPT and teeing where I sourced turbo water, feeding water with nice braided lines.
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