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Leaning out on idle and dies..

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Old 08-09-2020, 12:02 PM
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Question Leaning out on idle and dies..

Hi Guys!
Just joined cause ofcourse i want to receive help but also because i want to learn.
I am having problems with my 91' Turbo miata:
- 300zx turbo
- MS2 ECU

I just bought the car and had it tuned like 8 weeks ago. Everything was running OK but since yesterdat the following occured:
I was driving and all off the sudden the throttle started to react weird. Dunno how to say in English but it was like bogging and stalling , when releasing gasw and pressing clutch the engine would die...I limped it home with 10 restarts and constant shutter and stutter...Now when i start the car it will idle fine for 3-6 secs then starts leaning out like crap...Somebody said fuel flow or pump...i added some attachment because i dunno how to explain correctly. Your help is appreciated!

- car was tuned and ran fine

i also attached a short log, but since im new i might have done the log wrong...i started it before the car was on and then stopped it when it stalled...
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2020-08-09_17.34.18.mlg (78.9 KB, 30 views)
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Old 08-09-2020, 12:31 PM
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Yup, running leaner and leaner until it stalls, as the extra fuel from After Start Enrichment tapers off. Check your fuel pressure. You could also try removing the vacuum line from the fuel pressure regulator, removing the vacuum at idle should increase fuel pressure by ~6psi to see if that helps. But regardless, pressure needs to be checked. Attach your tune too.
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Old 08-09-2020, 01:22 PM
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Originally Posted by curly
Yup, running leaner and leaner until it stalls, as the extra fuel from After Start Enrichment tapers off. Check your fuel pressure. You could also try removing the vacuum line from the fuel pressure regulator, removing the vacuum at idle should increase fuel pressure by ~6psi to see if that helps. But regardless, pressure needs to be checked. Attach your tune too.
thanks!
IS there a way in TS to check fuel pressure.. i see load..
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Old 08-09-2020, 04:07 PM
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You'd have to plumb a sensor. This is generally done on a stock system with an 1/8NPT T, with 5/16" bungs on the run, and a 0-5v fluid pressure sensor in the T. This is put anywhere in the feed line. Aftermarket rails sometimes have an NPT spot for the sensor, and most aftermarket fuel pressure regulators do as well.

The three wire FPRs are generally grounded, 5v (can use 5v ref from TPS/MAP/etc), then the signal wire needs to go to any analog input on the MS, and you'll set that in TS to a generic sensor input.
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Old 08-10-2020, 04:51 AM
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Originally Posted by curly
You'd have to plumb a sensor. This is generally done on a stock system with an 1/8NPT T, with 5/16" bungs on the run, and a 0-5v fluid pressure sensor in the T. This is put anywhere in the feed line. Aftermarket rails sometimes have an NPT spot for the sensor, and most aftermarket fuel pressure regulators do as well.

The three wire FPRs are generally grounded, 5v (can use 5v ref from TPS/MAP/etc), then the signal wire needs to go to any analog input on the MS, and you'll set that in TS to a generic sensor input.
Attached my tune
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2020-08-10_10.46.57.msq (115.7 KB, 52 views)
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Old 08-10-2020, 05:52 AM
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Default leaking turbo/manifold?

So update:
I have found some smoke coming from here:


Gasket?
And could this be why my car fluctuate rich to lean and then dies?

Last edited by Alcapachino; 08-10-2020 at 06:06 AM.
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Old 08-10-2020, 10:42 AM
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Originally Posted by Alcapachino
So update:
I have found some smoke coming from here:


Gasket?
And could this be why my car fluctuate rich to lean and then dies?
So i tightend up some bolts and checked the piping etc and car now runs...not great tho. i added 2 logs..suspecting vacuum leak?
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2020-08-10_15.31.26.mlg (1.47 MB, 20 views)
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Old 08-11-2020, 03:22 PM
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You'll want to remove that downpipe and have it sanded flat. You'll never get a great reading at idle with it leaking.

I took a look at the tune, and nothing looked out of the ordinary for the most part. You do have 15% EGO correction available, however your log never utilized it, since the only time your wideband actually registered was after the RPMs were at zero.
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Old 08-12-2020, 11:05 AM
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Originally Posted by curly
You'll want to remove that downpipe and have it sanded flat. You'll never get a great reading at idle with it leaking.

I took a look at the tune, and nothing looked out of the ordinary for the most part. You do have 15% EGO correction available, however your log never utilized it, since the only time your wideband actually registered was after the RPMs were at zero.

Im really lost the car is beeing spooky..it was running this morning on idle fine. Then i turned it on and imediatly started leaning out towerd 22.4 and shutting of, then it ran again with very bouncy afr values ..and it keeps going like this. Idle is fluctuating between 800-1100 and i can hear the car struggeling sometimes to stay on. I have attached 2 logs maybe someone can help me...
I have tightened the turbo and downpipe area no more smoke. I can however see that my crank pully isnt really smooth running. A bit wobbly but not massive...Also when the idles dip i can feel noticable shuttering from the seat/floor

So the situation from original post has changed :
- the car runbs rough but sometimes stays on
- I have been able to idle the car for 10 mins but sometimes it shuts off after 10 secs
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2020-08-12_16.37.05.mlg (348.7 KB, 17 views)
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Old 08-12-2020, 04:21 PM
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Have you looked at your first log? Your AFR is actually diving towards 9:1, not 22:1. Which makes sense cause your fuel correction for warmup is approaching 245%. Which is not what's in the tune you attached above. So either it's changed or you're not actually running the tune you posted. The fluctuation in idle will require some idle advance correction and fine tuning
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Old 08-13-2020, 10:17 AM
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Thanks for the help...

Running in the following problem:
Car starts , then goed in to nervous mode (fluctuating rpms) and goes lean or cuts fuel (22.4) then richens up and goes lean and dies....
What does this sound like? Cause im starting to think this is hardware/wiring.
IS there a check mode in TS to check all the connection or somethjing?

so for :

- maybe o2 sensor? Dont think so cause i unplugged the AFR to see what it does, same thing
- fuel delivery problems ?
- A sensor or some sort of wiring?
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