Hey all!

After some time of driving my car N/A I've decided to start my journey towards forced induction. My first goal is to make a proper N/A tune to learn the basics before moving on towards the bigger stuff. I've made a base tune, got the sensors calibrated as well as connected both MAP sensor and wide band to the onboard controller with the bare instructions that came along the ECU. But no matter what I try the car just wont start. It fired up without issues prior to the ecu swap. Everything mechanically is bone stock.

The starter cranks and I do hear both the relay and fuel pump activate on startup. After cranking for a while you can smell the gasoline in the air yet I feel as if there's no fuel going to the engine.

My hope is that someone here may find that wich I fail to see in either the tune or log. If there is anything specific I need to do due to it being a 1.6 NB, please let me know as there is not a lot of info online.

 

I opened your tune and noticed that the trigger pattern is set to Miata 99-05 which is definitely not correct.
I would really check that you've loaded the base tune exactly for the year and engine of the car before you go too much further. From there, we can zero you in to some decent values.

Once you get the base tune, I would browse https://tunes.speeduino.com/ and search for vehicles similar to yours. Just know that not all the tunes on there are safe but they should give you some good references for idle control and fuel/spark.

 

I decided to try and change the trigger pattern to those of earlier B6ZE models and ended up with backfiring. Progress but didn't feel right.
Went back to the Miata 99-05 setting and the car fired right up! The NB6 seems to share the same trigger as the NB8 and not any other.

There was no base tune specifically for a 99 NB6 that I could find so I went with the generic 99-00 one. It fires up but doesn't idle and dies without throttle. But compared to my previous tune that idled at 2-4k this seems like a safer option to start with. I will look into other tunes as reference to try and dial in the idle at the source you mentioned.

Thanks for the input!

 

I had a somewhat similar issue but related to hard start in my thread here: https://www.miataturbo.net/speeduino...-check-110336/

I have an NA6 which may have some differences with the idle valve and mine is also turbo-charged. But the idle settings should be similar and in that link my tune is posted. I can also dig up my naturally-aspirated tune that I used that idled nicely and behaved pretty close to stock. I'll look for it tonight.

 

Used your tune as a reference to tame the idle. Managed to get it to a reasonable RPM quite fast thanks to your setup, thanks!

Had to end my session due to the fuel pump sounding like a bee hive. Popped another tune in and the humming went away so I will have to look at them and compare to try and figure out why. AFR readings were equally bad on both tunes.
Will refuel the car tomorrow as the current has been stagnant for a while.

Posting my current setup.

 

Glad I could help! At a certain point, you're going to close the idle valve all the way so that the ECU fully controls the idle. And then you're going to adjust as needed. For my car, I always needed the idle speed setting slightly open to get it to be close to OEM. I found it took me a few weeks of adjusting to get the idle dialed for the temperature ranges I normally drove in.

Come back here and let us know how you're doing.

 

Hey!

Its been a hell of a week. Just wanted to update anyone reading on my progress.

I kept encountering issues with ignition when swapping from OEM ECU to the current one. It would fire up on the first crank every time with OEM but not the DIY-EFI. For a moment I thought I had either fried the board or that it was not engaging the main relay due to there being no spark and no fuel going into the cylinders even though there was fuel preassure. I ruled out the crankchaft position sensor as well as the camshaft position sensor after doing a composite log to see that the timing and values were correct.

Upon futher testing it became apparent that after plugging the OEM ECU back into the car and then spwapping it out it would ignite and start. But only once and then returning to the no start condition. The most appearent visual que that I ignored was the flashing immobilizer. Since I couldn't find any recource saying that it needed to be removed nor that it could interfere with the startup of an aftermarket ECU on a 1.6l NB I tried to look at other solutions. However, as a final solution I unplugged it efter doing another ECU swap and now it starts without fail everytime.

For anyone with an EUDM 1.6l 99-00 NB wanting to install a speeduino. Save yourself a headache and remove the immobilizer while installing the ECU. You will also not need to look at that annoying flashing immobilizer light as many other do.

Here is my current tune as reference as well.

 

well, strange

all my Miata PnP boards (mk1 NA, mk2 NB, mk2.5 NBfl) can just be plugged in and engine starts without doing anything with immo module. On mk1 NA you have just to remove one of fuses (identically as for SpeedyEFI boards) to control fuel pump and not to fry mosfet on board.

immo module on all mk1 mk2 mk2.5 just communicates with ECU then ECU decide to fire up spark and injectors or not. And controls immo light but nothing else. On mk2.5 NBfl there is a loop for starter blocking relay so you have to connect 2 wires after disconnecting immo board

wrting of EU Miatas as I live in Poland and selling them to EU mainly

 

After taking a brake from tuning the issue has surfaced once again. Called it too soon.

Damn. Wish that I knew about you earlier! Would have probably saved me some time and money.

Im desperate to try anything at this point. Is it pin D and L that are required to be connected on the mk2.5?

Might as well try that at this point.

 

according to schematic rather K to C (GND)



or just cut M line to immo warning bulb and leave module

 

Thanks Alex. Seems that wasnt the cause either.

From what I can gather its something after the ecu then. The ecu flashes while cranking to indicate spark but the coil doesn't seem to produce any spark anymore after a while. It's as if power to the coil pack/igniter is cut after running/cranking for a while and then turning the ignition off.

Could it be that both coil packs are bad even though they fire with OEM ecu?

 

If coils are working on OEM ECU they are rather good. What's your dwell settings? 3ms running 5ms cranking is working well with OEM coils.

Another question is driving level for coils, I mean which level is to charge coils and which to fire Spark. If set incorrectly you can even destroy coils because they will be charged for waaaay to long.

 

Currently using 3ms running and 6ms cranking.

Are you referring to dwell voltage correction or something else?
Dwell voltage correction seems so be around 100+-6 across the different voltages.

 

I mean "Spark Outputs triggers" setting. On my boards is as follows



I would ask DIY-EFI support for assistance. This should work out of the box

 

Thanks for all the help Alex!

Managed to solve the problem by getting a new coil pack.
Seems like I started this project at the same moment they decided to give in to their age. Runs better than ever in stock ecu. The speeduino? Not as great but I will take this as a W.

My current fueling seems to be too rich wich is apparent by the smell of fuel and the obvious puddle of gasoline beneath the exhaust. To make matters worse there are pops in the exhaust every now and then, most likely due to unburrnt fuel, while I'm receiving a decent AFR reading. The pops occur in combination with a lean spike as seen in the log.

My best guess is that I've gotten the base fuel wrong for my injectors. I've tried searching the web but cant find anything regarding 195500-3030 flow rates. Are they 230cc or perhaps even less?

 

well, you have few things messed up:
- i would sayVE table looks weird in some areas
- WUE table looks really bad. Definitely it should go to 100 at operating remperature. You have 120. Correct this first

my WUE table looks like:

 

Time to update on my progress for those still reading.

I changed the injector flow rate to 240 as a higher value than they output would result lack of fuel during more extreme conditions rather than too much fuel and potential leaks while at idle. While trying to get the car to run I had set the WUE to 120 in order to see if my lean condition would change but forgot to revert it.

Everything runs great and I am testing different AFR tables to find a sweet spot between fuel economy while cruising and power while WOT. Cold start idle isnt perfect but Im working on it to get the closed loop as close to oem as possible. There was an issue regarding intermitten misfires but that was easily solved by downgrading the firmware from the latest to the 202402 version. Seems like the 202501 still has a lot of known issues to work out.

I'd like to thank AlexE once again for all the help and support!