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It's Paid For.
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Discussion Starter #1
Heres the story. I suffer from the tank like idle as do many other Altima owners. So I decide to adjust the idle using the IACV. Now if I open the valve to idle at about 1000 rpm's the car is smooth as butter, only one downside, the car lacks noticible power. Close the valve, idles rough but the power returns. Can someone please tell me how the IACV actually works, as in what is going on inside? Why would there be a decrese in performance? Any other way to smooth out the idle. Oh and she idles at the appropriate 700 rpms, with no adjustments.
 

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Resistance is futile
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3,202 Posts
Did you disconnect the TPS before you messed with the IAC valve?
 

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Registered User
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4,020 Posts
The IACV is used to adjust idle speed...idle speed should be 550 ~ 650. There is really no point in adjusting it lower then that. The IACV allows the car to return to an idle point before the TPS resets itself after a decel/clutch depress. If it is set too low the idle will drop sharply after decel/clutch depress until the TPS kicks in and brings it back up. Now on the flip side, if it is set too high the TPS won't kick in at all because the IACV is set too high and override the TPS setting.
 
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