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Old Oct 12, 2017 | 11:22 AM
  #1  
KingKoopa93's Avatar
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From: Massachusetts
Still at a loss.

I've been having an idle problem with my car, "at times" haven't found any other threads regarding the same issues I'm having. Randomly at idle my car has stalled on me, twice. Besides that at lights it tends to drop down to a point where it wants to stall but almost revs itself back uoto 1k rpms. I've gotten a compression text and my engine checks out fine. Also cleaned the maf sensor and throttle body with no luck. This problem seems to be completely random. Anyone have this same issue? Won't be fuel pump but could it be the filter?

no CEL lights ever
65k miles
2010gt mt

my only mods are turbo xs cat back
and BHR ignition coils.
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Old Oct 12, 2017 | 11:37 AM
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What were the compression test results? Stalling could be something as simple as a vacuum leak.
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Old Oct 12, 2017 | 11:38 AM
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From: 2017 Miata RF Launch Edition
Time to start doing some data logging. Get RPM, MAF rate, STFT, AFR, throttle position... Whatever else sounds interesting.

I wonder what your fuel trim looks like as it stalls or does it's little RPM dip.
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Old Oct 12, 2017 | 11:42 AM
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From: Massachusetts
Rotor 1 at 294.
7.6
7.7
7.7

At 300
8.6
7.7
7.8

at 303
8.4
7.7
7.8

rotor 2
at 299
8.4
8.0
8.4

at 297
8.2
8.8
8.4

at 300
7.9
8.4
7.7
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Old Oct 12, 2017 | 11:44 AM
  #5  
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Originally Posted by NotAPreppie
Time to start doing some data logging. Get RPM, MAF rate, STFT, AFR, throttle position... Whatever else sounds interesting.

I wonder what your fuel trim looks like as it stalls or does it's little RPM dip.
what would I use to gather these numbers? Some sort of ecu reader?
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Old Oct 12, 2017 | 11:46 AM
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Numbers are not great on Rotor 1 but technically still good. But yeah seeing what your fuel trims are at warm idle might give us some clues.
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Old Oct 12, 2017 | 11:53 AM
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Originally Posted by 9krpmrx8
Numbers are not great on Rotor 1 but technically still good. But yeah seeing what your fuel trims are at warm idle might give us some clues.
yea unfortunatelyfor me it's good enough to where I won't be able to get a new one before my warranty expires lol!. I'll so some tinkering around and try and get some data. Thanks for the responses fellas😊
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Old Oct 12, 2017 | 11:57 AM
  #8  
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From: 2017 Miata RF Launch Edition
I agree with 9k. The numbers from Rotor 1 aren't spectacular but I've seen much worse from engines that still run just fine.

Get a bluetooth OBD-II adapter (any $20 unit from amazon will work) and an app for your smartphone. I hear Torque is popular on Android and I like OBD Fusion and DashCommand on iOS.
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Old Oct 12, 2017 | 04:55 PM
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Originally Posted by NotAPreppie
I agree with 9k. The numbers from Rotor 1 aren't spectacular but I've seen much worse from engines that still run just fine.

Get a bluetooth OBD-II adapter (any $20 unit from amazon will work) and an app for your smartphone. I hear Torque is popular on Android and I like OBD Fusion and DashCommand on iOS.
Ok sweet! Sounds easy enough. Unrelated to op but do I still have a good amount of life left in that rotor? Now I'm worried lol
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Old Oct 12, 2017 | 07:37 PM
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If you are looking at Bluetooth adapters, be careful. Some are ISO and Adroid specific.

I have an IPhone and use OBD Fusion (paid version) $10.00.

For the adapter I went with this one :
Amazon Amazon

Some of the cheap $9.00 - $12.00 adapters don't capture all the data the more expensive ones do. Mine will pretty much tell you everything you need to know, fuel trims ST and LT, 02 readings, A/F, MAF readings and many many more. For less then $30.00 you can have a pretty rockin' backyard scanner.
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Old Oct 12, 2017 | 10:01 PM
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gotta feeling it's vacuum leak, hunt it down.
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Old Oct 13, 2017 | 04:42 AM
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Originally Posted by Dave04
If you are looking at Bluetooth adapters, be careful. Some are ISO and Adroid specific.

I have an IPhone and use OBD Fusion (paid version) $10.00.

For the adapter I went with this one : https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Some of the cheap $9.00 - $12.00 adapters don't capture all the data the more expensive ones do. Mine will pretty much tell you everything you need to know, fuel trims ST and LT, 02 readings, A/F, MAF readings and many many more. For less then $30.00 you can have a pretty rockin' backyard scanner.
Good looks man! Greatly appreciated
Originally Posted by Okki-Jakarta
gotta feeling it's vacuum leak, hunt it down.
I do enjoy a nice scavenger hunt 😂 but that seems pretty straight forward. Are there lots of potential spots I could have a leak? Or is it pretty simple to isolate the leak
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Old Oct 13, 2017 | 05:48 AM
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im not really familiar with this but there's a smoke technique. look it up
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Old Oct 18, 2017 | 11:38 AM
  #14  
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Bought one of those readers, in mail as of yesterday. Cleaned the throttle body and a huge amount of corrosion off one of the terminals on my battery and it idles a lot better still a little jumpy but I might have narrowed it down some
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