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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 03-27-2007, 08:51 PM   #1
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Default High idle, rough when warm.

Installed tan top 1.8s today. I switched some of my couplers, and did a bunch of other crap since it ran last. Notably, I switched the pipes connecting my I/C, which means the hot side pipe is now the cold side and vice versa. The BOV is now on the cold side.

Subsequently, the "idle valve?" (first pic in vBgarage) which normally is a short hose connected just before the throttle body now is connected just after the turbo outlet, before the I/C (the other side.) I have no cord for my camera, so I cant post pics, but it's easy to imagine looking at the I/C pics in my vBgarage.

My problem is that when jumpstarted (battery cable not disconnected when left for a while) the idle is about 1500 RPM but it's smooth. When it warms up, the idle drops to around 900 RPM or so but gets real choppy, and sounds like it wants to die. Sometimes it bounces from 750 to 1000 RPM, and just sounds wrong.

Could it be the air idle valve connection? I have a hundred things to go over, I want to make sure before I tap my BOV adapter pipe. The wideband shows quite rich at idle, about 12.5.


vB: https://www.miataturbo.net/forums/vb...do=view&id=925
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Old 03-27-2007, 11:42 PM   #2
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Switched the I/C pipes back to original position. JB is curing, I'll start it tomorrow, and pray tonight.
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Old 03-27-2007, 11:48 PM   #3
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maybe thats why my idle always hunted with the turbo on, I didn't have a damn thing hooked to that.
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Old 03-28-2007, 09:52 AM   #4
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im sure it had to do with the length and position of the line.

or could have been a vacuum leak.
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Old 03-28-2007, 05:23 PM   #5
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Much shorter line helped somewhat. Less hunting, idles at 900 RPM or so. Still does not sound perfect. My wideband shows error 4 which is either the cable or the heater sensor calibration. It's been awhile since last calibration, so that's next time. Sigh.
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