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Old 09-03-2014, 03:50 PM   #1
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Default Rough idle and lean

Car always drove fine on the highway and on streets. However the idle was always an issue. Rough and searching. Would drop to 13then back to 16 constantly trying to find a clean idle.

MS3x is the ECU on a 95 turbo 1.8 i attached a data log of it.

I was thinking maybe my timing was off so i pulled out the timing gun and saw the pulley had two lines. A yellow -then> a white mark. The marks were lined up to 10 btdc to the yellow and the TDC was set to the white mark.

Car still idled crapply, and my AEM wideband was showing lean completely. Not sure whats really going on, any advice?
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File Type: msl idle_problem.msl (140.3 KB, 39 views)
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Old 09-03-2014, 05:22 PM   #2
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now i have this error. what the hell
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Rough idle and lean-7mp4pyml.jpg  
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Old 09-03-2014, 07:39 PM   #3
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You are trying to do two things with one output, so nothing works till you fix the conflict. You shouldn't need the tach out for a NA miata, unless you have weird cops? If it was working, you had to change something to cause this to happen. The idle sounds like the surrounding VE cells need tuned, it hunts across cells, so some cells are lean and others are rich. Causes hell on CL idle.

Is your IAC valve driven by the tach out on the MS3? Should be FIDLE, or at least I'm sure that's the most common.

On the bottom of the Basic/Load settings tab there's a option for Feature list showing I/O pins, should show the conflict.
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Old 09-03-2014, 08:03 PM   #4
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Not sure if the IAC valve is driven by it. I just PNP the harness the only thing i added was my aem wideband to the pink wire on the harness.
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Old 09-03-2014, 08:10 PM   #5
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Who does PNP MS3? I'd ask whoever you got it from.

Or restore an older tune file that doesn't have the conflict.
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Old 09-03-2014, 08:17 PM   #6
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braineack built it for me. Im checking my VE table and its a mess. Fixing the tables now
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Old 09-03-2014, 08:26 PM   #7
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Somewhere in the settings you have enabled the tacho out to be same output as the idle valve. Has nothing to do with your harness.
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Old 09-03-2014, 08:28 PM   #8
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Hmm now to find that in my settings. Could that be the reason why my tach isn't working ?
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Old 09-03-2014, 08:45 PM   #9
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Yeah, probably lol

Your Miata does use tach out to drive the cluster, I was wrong earlier.

If I had to guess, you should go to idle control settings and change the control pin to FIDLE. I'd ask the brain first though, since he built it.
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Old 09-03-2014, 08:57 PM   #10
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Just tinkered with the car, realized i was having poor and low vacuum. So i started to look for a vac leak. Made sure the line going to my ECU wasnt kinked, and the FPR and BOV seemed okay too. Realized my #1 injector seal to block was leaking and sucking in the spray. So i guess that might explain why my idle is so off.
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Old 09-04-2014, 03:26 PM   #11
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Most likely. Also I believe you should not need to thinker with the outputs and so on since most likely your ECU was built for your setup and you would only need to tune it. So perhaps find the original msq file that came with it and load it back up!
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