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Help! Turbo Miata High Idle

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Old 02-24-2017, 10:20 PM
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Default Help! Turbo Miata High Idle

I have a 1993 Turbo Miata running a megasquirt 2 plug n play. It currently idles at 2700 rpm! I have tried everything. I got a new throttle body. The idle adjustment screw is screwed in all the way down. I tried playing with all the megasquirt idle controls with no success. I made sure the throttle cable was good. The throttle body has a new gasket. Does anyone have any idea why it could be idling so high. Any suggestions will be greatly appreciated. Is it my megasquirt settings? Anything mechanical? Thank you!!

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Old 02-24-2017, 10:35 PM
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Post a datalog and tune file (msl and msq)
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Old 02-25-2017, 12:14 AM
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Big vacuum leak,,check the rubber plug on the back corner of the intake manifold . Fredb
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Old 02-25-2017, 07:58 AM
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Originally Posted by acedeuce802
Post a datalog and tune file (msl and msq)

Here are the datalog and tune
Attached Files
File Type: msl
HighIdle.msl (341.6 KB, 111 views)
File Type: msq
CurrentTune.msq (113.9 KB, 221 views)
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Old 02-25-2017, 12:26 PM
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Check for vacuum leak, also your idle fuel cells may be uneven, does it hunt up and down for idle.

Don't go by what I say though, still learning, my idle issues were pretty much tuning issues and a vacuum leak, which I found by spraying some brake clean around the intake when it was running, it will bog down the motor a quick sec when you find it. . . also even out your idle area in your fuel table, that will help as well.
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Old 02-26-2017, 02:21 PM
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does anyone know what I need to do? I'm trying to sell the car so I need to get this done ASAP. Thanks!!
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Old 02-26-2017, 02:40 PM
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I'll buy it for 2 nickles.
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Old 02-26-2017, 03:38 PM
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I'm not where I can open the msq so tell me where your IAC valve minimum DC is set?
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Old 02-26-2017, 05:18 PM
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tune.
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Old 02-26-2017, 05:53 PM
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Does the RPM change at all when the idle DC% changes?
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Old 03-03-2017, 07:08 PM
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Originally Posted by sixshooter
I'm not where I can open the msq so tell me where your IAC valve minimum DC is set?

Here is a screenshot of the IAC valve DC. there is a setting under Idle control called valve mode. There is normal and inverted I was on inverted so would changing it to normal do anything??. Thanks
Attached Thumbnails Help! Turbo Miata High Idle-screen-shot-2017-03-03-7.03.28-pm.png  
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Old 03-03-2017, 07:43 PM
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Unplug your IAC.
Unplugging it will close the valve.

If idle drops, you have a setting problem.
If it remains high, at 2700 RPM like you said, you have a big vacuum leak.

Check to see if you still have the restrictor orifice in your PCV line.
Check your brake booster / booster line.
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