[help needed] 1993 Mazda Miata

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starsky
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1993 Mazda Miata

Post by starsky »

Hello Everyone,

I just received a microRusEFI adapter Miata NA 48pin PnP board from Andrey for my 93' Miata NA6.

The car is completely stock for now and I plan on installing the board in the next few days.

After I get the board running I plan on doing the following mods right away:

VTPS (Kia part ordered)
AFM Delete
AFR wideband (any recommendations?)

After I get a good feel for the tuning I plan on adding a little boost!

Thanks for reading!
starsky
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Re: 1993 Mazda Miata

Post by starsky »

My Kia VTPS sensor should be delivered Monday. My understanding is the signal and +5 volt contacts are reversed, does the firmware autodetect a reverse signal VTPS? Do I need to do any pin mods on the board?

Thanks!
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AndreyB
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Re: 1993 Mazda Miata

Post by AndreyB »

starsky wrote:
Sat Dec 05, 2020 9:31 pm
does the firmware autodetect a reverse signal VTPS? Do I need to do any pin mods on the board?
Software definitely does NOT auto-detect this, there is a jumper on the board to mod. I will make sure it's documented later tonight.

But the real question is: did the board start the car as is, 100% OEM?!
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starsky
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Re: 1993 Mazda Miata

Post by starsky »

AndreyB wrote:
Sat Dec 05, 2020 9:40 pm
starsky wrote:
Sat Dec 05, 2020 9:31 pm
does the firmware autodetect a reverse signal VTPS? Do I need to do any pin mods on the board?
But the real question is: did the board start the car as is, 100% OEM?!
I have not had a chance to install the board yet, I definitely will test it before any mods for sure!

Thanks again!
Simon@FutureProof
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Re: 1993 Mazda Miata

Post by Simon@FutureProof »

Is there something special about the TPS?

M52 TPS is reverse signal (lower ADC open than when closed) and RE has been working fine with that for a long time.
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starsky
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Re: 1993 Mazda Miata

Post by starsky »

OrchardPerformance wrote:
Sat Dec 05, 2020 11:46 pm
Is there something special about the TPS?

M52 TPS is reverse signal (lower ADC open than when closed) and RE has been working fine with that for a long time.
The Kia TPS uses the same connector as the original Miata TPS, so no adapter harness is needed.
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AndreyB
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Re: 1993 Mazda Miata

Post by AndreyB »

OrchardPerformance wrote:
Sat Dec 05, 2020 11:46 pm
Is there something special about the TPS?
OEM 1993 miata does NOT have a TPS, it has two switches. Miata people are lucky that there is a proper Kia TPS with similar connector.
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starsky
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Re: 1993 Mazda Miata

Post by starsky »

So I am going to be plugging this ECU in today, do I need to hook up the MAP sensor or does the base tune use the stock AFM?

Thanks
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AndreyB
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Re: 1993 Mazda Miata

Post by AndreyB »

i _think_ i clicked "vaf" option on yours.

Just a reminder that it's one click to change from "VAF" to "MAP" tune and back.
image.png
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starsky
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Re: 1993 Mazda Miata

Post by starsky »

I finally had time to plug the unit in today.

I warmed up the car to operating temp, disconnected my battery, unplugged my stock ecu and plugged in the rusEFI ecu.

Reconnected the battery and attempted to start the car.

After a few cranks it definitely tries to run but dies right away.

I do not have the MAP connected, what is the first thing to check?

I plugged my stock ecu back in and it started right up.

Thanks!
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AndreyB
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Re: 1993 Mazda Miata

Post by AndreyB »

Perfect, something is not right.

For us to know what's going on we need data. We need your tune and your cranking log.

Please have TunerStudio connected with rusefi_microrusefi.ini project, please write a log while cranking.

Please https://github.com/rusefi/rusefi/wiki/HOWTO-upload-tune and https://github.com/rusefi/rusefi/wiki/HOWTO-upload-log
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starsky
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Re: 1993 Mazda Miata

Post by starsky »

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AndreyB
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Re: 1993 Mazda Miata

Post by AndreyB »

https://rusefi.com/online/view.php?msq=291&dialog=engineChars

your tune shows "MAF" fuel strategy so your problem is NOT about MAP being not connected, now opening your log
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AndreyB
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Re: 1993 Mazda Miata

Post by AndreyB »

Your log shows lack of MAF signal. Let me call a guy...

As a work around I would suggest trying to start with a MAP sensor hooked up after your change your tune to MAP.
image.png
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stefanst
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Re: 1993 Mazda Miata

Post by stefanst »

It appears there is an issue with the default tune. The MAF sensor is on Pin 40. So the MAF input should be set to 40-AV9.

No idea how that one snuck in!
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AndreyB
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Re: 1993 Mazda Miata

Post by AndreyB »

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stefanst
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Re: 1993 Mazda Miata

Post by stefanst »

Correct. Looks like the online version does not list pin 40.

This is how it should be set up:
40-AN Vlt 9.png
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starsky
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Re: 1993 Mazda Miata

Post by starsky »

Thanks guys!

Changing the PIN got it to start, it just ran really rough. Here is my log:

https://rusefi.com/online/view.php?log=77
stefanst
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Re: 1993 Mazda Miata

Post by stefanst »

Did you crack open the throttle to keep it running in that last log?

If not, your MAF readings in idle are quite different from what my old '91 used to get. Your voltage reading is lower, which results in higher calculated airflow and therefore more fuel added. If it's too much fuel, that explains the running rough issue.

One way to check, if your MAF readings are off, is to just lean out your fuel map everywhere.

Go to "Fuel" -> "VE"
Here mark all cells with the mouse cursor. Then hit the "*" key on the keyboard and enter "0.8" as a multiplier. This will cut 20% off the fuel delivered. If the car runs better now, we know that it was running too rich. If it got worse, it was running to lean. No change would indicate that it's not a fuel issue.
starsky
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Re: 1993 Mazda Miata

Post by starsky »

The throttle was not cracked, I just started the car like normal and left the throttle closed.

I'll try your suggestion tomorrow and report my results.

Thank you for all the help
stefanst
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Re: 1993 Mazda Miata

Post by stefanst »

Then I'm pretty sure it's fuel.
I just found a log of my car idling. The mass air flow at 1000rpm is around 13.5kg/hr. This results in an injection pulse of approx 2.3ms. You are showing a mass air flow of around 22.5kg/hr, resulting in approx. 3.2ms injector opening. So your car is getting approx. 40% more fuel than mine. No wonder it's running rough.

From this data, I would even reduce the VE table by 30% (multiply by 0.7) and see what happens.
starsky
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Re: 1993 Mazda Miata

Post by starsky »

I've always suspected my car for some reason is running rich, even with the stock ECU. Gas mileage is not great and there is a stronger fuel smell when warming up. Would a bad O2 sensor be causing this?
fan
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Re: 1993 Mazda Miata

Post by fan »

Hi @starsky,

I actually suspected the same, if you have your stock narrowband and the rusefi board you can actually check if that is true by setting a custom wideband profile in Sensors->EGO, type Custom, low voltage 0, low AFR 0, high voltage 5, high value 5, and the gauge should output something between 0-1V over the stock tune. Mine is broken, and when I was installing my wideband yesterday I can tell that the old narrowband sensor hasn't been changed for at least 10 years and is seized in the bung. Put some penetrating oil and it loosened, switched to wideband, tuned the VE table and the engine runs a lot better.

I am still a rookie in engine tuning, but this is my two cents :)
starsky
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Re: 1993 Mazda Miata

Post by starsky »

Hi All,

So I took a break from this during the Holidays, I will be getting back into it this week hopefully. I purchased an AEM AFR Wideband gauge and sensor and will be putting that in as well.

Andrey: You mentioned there are pinout mods needed for the reverse Kia TPS? Are the instructions available?

Thanks!
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AndreyB
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Re: 1993 Mazda Miata

Post by AndreyB »

Very limited telepathic abilities - please post logs & tunes where appropriate - http://rusefi.com/s/questions

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starsky
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Re: 1993 Mazda Miata

Post by starsky »

Hi guys, trying to get back into this project.

When removing the stock AFM and using a GM IAT, does the fuel pump pins have to be jumped at the connector? If so, does this mean the fuel pump will always be running when the car is on or is there another method of control?

Thanks!
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AndreyB
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Re: 1993 Mazda Miata

Post by AndreyB »

You can make one step into the future and start controlling fuel pump relay from rusEFI
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starsky
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Re: 1993 Mazda Miata

Post by starsky »

Ok guys,

I adjusted the VE, and then it ran a little rough still, and would almost die as I gave it throttle.

I then turned it off so that I can get a Log started but could not get the car started again.

Here is the log:
https://rusefi.com/online/view.php?log=196

I plugged in the stock ECU and it started up fine.

Thanks!
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AndreyB
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Re: 1993 Mazda Miata

Post by AndreyB »

Log cool, please post tune?
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starsky
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Re: 1993 Mazda Miata

Post by starsky »

AndreyB wrote:
Fri Apr 09, 2021 8:38 pm
Log cool, please post tune?
https://rusefi.com/online/view.php?msq=481

Thanks Andrey
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