1991 NA6 Miata (Stock)

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fan
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1991 NA6 Miata (Stock)

Post by fan »

Hi all,

I am currently experimenting with the Miata 48 pin board for MRE (version 0.2) board.

Just got it installed, tried cranking but not starting :(

My current configuration:

* All stock
* Vacuum line for MAP tee'ed from the FPR

Problems I encountered:

1. Using the Micro USB connection, writing a preset MSQ tune results in "Burn Page 0 Failed" and the controller disconnects.
2. No presets for the release version (https://github.com/rusefi/rusefi/releases/tag/20200831)

This is my daily, so any help is really appreciated!

Fan
stefanst
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Re: 1991 NA6 Miata (Stock)

Post by stefanst »

When you say "writing a pre-set tune" are you referring to "Popular Vehicles" under the "Controller" menu?

If TS still connects to your rusEFI, then download the tune currently on the rusEFI and post it here. The question is if it's standard tune that gets uploaded when the unit is new or if it still has the appropriate Miata NA6 MAP tune.
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Re: 1991 NA6 Miata (Stock)

Post by AndreyB »

The act of using "Popular vehicles" is a bit fragile in terms of burning and etc - we have red and blue warnings on that dialog.

Can you please provide _exact_ details on what buttons do you click in what order?
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I guess it's time for us to make a HOWTO video on this subject.
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fan
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Re: 1991 NA6 Miata (Stock)

Post by fan »

I am able to load the NA6 preset to the board with Andrey's method - now it still does not start - I think the fuel pump is not working, is there a way to test it and what may be the problem?
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fan
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Re: 1991 NA6 Miata (Stock)

Post by fan »

I did some more experiments, and I think I found a problem: There is a strange looking "starter disable" circuit hooked on the big harness on top left of the engine bay (which is on "BYPASS", so I can start the vehicle without issue with the original ECU).

When the "starter disable" is switched to "ON", suddenly the radiator fan started (I think that is desired? as the MS GUI says "fan on"?). However the vehicle still won't start. Also it is very strange that the original ECU works with the "BYPASS" configuration, and the radiator fan only starts when the engine is hot.

I wish there is a list of "what should happen" when one switch the ECU unit, so I can differentiate and diagnose.
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Re: 1991 NA6 Miata (Stock)

Post by stefanst »

Take a look here:
https://github.com/rusefi/rusefi/wiki/Installing-a-PnP-rusEFI-unit-in-a-Miata-startup-and-test

You pretty much got to step 4. Now it's time for step 5
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Re: 1991 NA6 Miata (Stock)

Post by stefanst »

One more note: On the NA6 Miata the Fuel Pump is controlled by a switch in the MAF. The ECU has no impact.
fan
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Re: 1991 NA6 Miata (Stock)

Post by fan »

Yeah I tried that, but there is no spark-the injectors are working normally...
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Re: 1991 NA6 Miata (Stock)

Post by fan »

I switched back to stock ECU board, and the car runs perfectly. So it's either a configuration issue or a H/W fault in the rusEFI board.
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Re: 1991 NA6 Miata (Stock)

Post by fan »

My stock ECU is a DENSO "remanufactured" B61P-18-881R, just fyi.

Completely out of ideas now...
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Re: 1991 NA6 Miata (Stock)

Post by fan »

I tested the two spark outputs, the LEDs associated with the COIL1 and COIL2 are working.
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Re: 1991 NA6 Miata (Stock)

Post by stefanst »

You are positive the spark plugs don't fire, yet the LEDs light up? That's certainly weird. Just to make sure: Ignition is on? How did you confirm spark? A sparkplug in the sparkplug boot and grounded to the valve cover?

If you are certain that the LEDs are lighting up, but there's no spark at all, I suspect your immobilizer unit may be doing something- like cutting power to the coils or igniter. It may be expecting something from the stock ECU that we just don't know what it is. Can you check if you have power to the igniter with ignition on? It should be the blue wire.
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If the LEDs are flashing and the blue wire at the igniter has 12V I have no clue why there would be no spark.
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Re: 1991 NA6 Miata (Stock)

Post by stefanst »

One more question: Does TunerStudio show an rpm when you are cranking the engine?
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Re: 1991 NA6 Miata (Stock)

Post by AndreyB »

Yes, TunerStudio shows RPM during cranking.

Have you noticed the "bench test" buttons in TunerStudio? you should be able to hear both injector and spark tests - injectors are much louder, to hear spark you need a really quiet environment.
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Re: 1991 NA6 Miata (Stock)

Post by AndreyB »

I assume we are starting to suspect that many things are not working as expected.

At the moment we are pretty blind, in order to get less blink please share some data with us.

Please make a TS log file of your cranking attempt and share it with us - see https://github.com/rusefi/rusefi/wiki/HOWTO-upload-log on what's the best way to do so.
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Re: 1991 NA6 Miata (Stock)

Post by fan »

I have recorded the log here:

https://rusefi.com/online/view.php?log=37

> One more question: Does TunerStudio show an rpm when you are cranking the engine?

Yes

> Have you noticed the "bench test" buttons in TunerStudio? you should be able to hear both injector and spark tests - injectors are much louder, to hear spark you need a really quiet environment.

Yes I already did that, the injector noise can be heard, but I can't hear the sparks. I currently cannot confirm whether I have spark or not-I plan to buy a spark plug wrench so I can remove and see.

Also, I think the immobilizer is just a red herring...
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Re: 1991 NA6 Miata (Stock)

Post by fan »

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Re: 1991 NA6 Miata (Stock)

Post by AndreyB »

logs show RPM. I am not 100% sure but logs look like cranking is really short? for how many seconds are cranking it?

rusEFI cranking/starting takes longer than OEM :(
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fan
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Re: 1991 NA6 Miata (Stock)

Post by fan »

I tried cranking for about 3 seconds, no avail... I have only stock o2 sensor but I think that will not affect cranking? I can test later with a wideband tho. BTW, stock cranking is <0.5s.
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Re: 1991 NA6 Miata (Stock)

Post by fan »

This is a longer crank (4.3s). https://rusefi.com/online/view.php?log=39

Please disregard the last portion, I turned off the ignition and the RPM readings go crazy...
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Re: 1991 NA6 Miata (Stock)

Post by AndreyB »

Wideband has nothing to do with cranking.

Can you please post a video on youtube?

"no starting" is a very wide range of conditions. it's not even trying to fire at all? if you have RPM on tuner studio gauge it's supposed to be fueling and sparking, and starting.
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Re: 1991 NA6 Miata (Stock)

Post by stefanst »

My hope is that the car will actually run as-is. Looking at your logs, the ECU never really gets a chance to complete two injection/ignition cycles to start the car. AS @AndreyB already pointed out, rusEFI is not quite at OEM ECU speed when it comes to recognizing cranking. This means that it will typically take about two full revolutions of the crank before the ECU actually knows where the crank is. THEN it starts injecting fuel and sparking.
Your logs show 1.5s of actual rpm readings at best. Considering that the ECU may not be perfectly tuned for your engine yet, this is likely not enough time. Give it 10, or better, 15-20s of cranking. It will seem like an eternity. But at 240rpm, it's only 2 cycles per cylinder per second. Considering that the ECU starts seeing the crank position after maybe 2-3s, even with 10s cranking you only get 10-15 cycles for the engine to catch.
If you don't succeed first try, play with the throttle a little.

Hints:
You don't need to remove a spark plug from the engine to test spark. You can also use a spare spark plug you may have lying around somewhere. Or you can put something else (made of conducting metal) in the spark plug boot and have it arc to ground (valve cover). The goal is to have a metal connection to the outlet of your coil and a small air-gap from that piece of metal to an engine ground- usually the valve cover.
Try a Phillips head screwdriver for example. Push it into the spark plug boot. Take care to not expand the metal clip in the boot. The diameter should probably be about 3/16" or so (best guess). Try and have the closest distance between the metal object and the valve cover between 1/16" and 1/8". That should work for a nice, visible spark.

You don't need to swap the rusEFI into the stock housing for testing purposes. I use a piece of cardboard and masking or electric tape to insulate the bottom of the pcb and then just plug it in like that.
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fan
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Re: 1991 NA6 Miata (Stock)

Post by fan »

Hi all,

I think it's the fuel pump, because I just tested spark at 11pm when it's very quiet, and I can clearly hear the sound of sparks. Tried cranking for 30s, no avail... so it's probably some signal from the ECU to the fuel pump (Circuit Opening Relay?) that is not hooked on the rusEFI board.
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Re: 1991 NA6 Miata (Stock)

Post by fan »

I am thinking about jumping the fuel pump relay on the diagnostics port tomorrow when I have light.

So Stefan do you know why the pin 1C is not hookup up? I think that could be used to control the fuel pump:
https://www.diyautotune.com/support/tech/hardware/diypnp/documentation/application-docs/1990-1993-mazda-miata/
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Re: 1991 NA6 Miata (Stock)

Post by stefanst »

fan wrote:
Wed Sep 23, 2020 3:47 am
Hi all,

I think it's the fuel pump, because I just tested spark at 11pm when it's very quiet, and I can clearly hear the sound of sparks. Tried cranking for 30s, no avail... so it's probably some signal from the ECU to the fuel pump (Circuit Opening Relay?) that is not hooked on the rusEFI board.
The Circuit Opening Relay is powered directly by the ignition switch. The ECU can "see" the signal on pin 1C, but it does not generate it. Check page 3 here. http://www.neomiata.com/garage/Wiring%20Diagrams/Wiring%20Diagrams%201990-1996/1991_Miata%20Wiring%20Diagrams.pdf

If you are uite certain it's the fuel pump, you can circumvent the signal from the MAF. You can jumper it in the diagnostic connector
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just jump Fuel Pump to GND
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Re: 1991 NA6 Miata (Stock)

Post by fan »

So I brought my car to a mechanic specialized in Miatas, and he couldn't figure out what is happening either. We tried jumping the fuel pumps, pumps run but fail cranking. Now we both think that either the configuration is not right or the ECU itself is probably faulty...
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Re: 1991 NA6 Miata (Stock)

Post by mck1117 »

fan wrote:
Thu Sep 24, 2020 2:28 am
So I brought my car to a mechanic specialized in Miatas, and he couldn't figure out what is happening either. We tried jumping the fuel pumps, pumps run but fail cranking. Now we both think that either the configuration is not right or the ECU itself is probably faulty...
Did you try the diagnostic connector jumper?
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Re: 1991 NA6 Miata (Stock)

Post by AndreyB »

I have 1.6 engine sitting on the shelf, I guess it's time to make it into a test bench for final ECU testing.

On the other hand I bet that Stefan's test setup would be at least equally functional, it must be something trivial. Is it time to ship the ECU back for a test at home and maybe ship you a repacement?

Thank you for your patience. So far these were starting.
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Re: 1991 NA6 Miata (Stock)

Post by stefanst »

I think @AndreyB is right. I will build another ECU for you and I think I can find a car to test it in before shipping.
This is really strange though: You see rpm, injectors and coils are working. In theory, the engine should start.
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Re: 1991 NA6 Miata (Stock)

Post by fan »

@mck1117 Yes, we used the DIAGNOSIS jumper box and the fuel pump was running (confirmed noise).

@AndreyB I agree, probably it's a subtle difference in ECU wiring. I am very busy for my studies, but I am more than happy to test anything (I have a DMM and an oscilloscope).

@stefanst Many thanks!
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