92Yata

I know its not uncommon to hear of a Miata owner with difficult startup issues but this has been beat to to the ground without a solution for many months and a few good tuners.

So currently I have a map on the car that does start the car somewhat decent and what I noticed in the last few days playing around with the tuners map revisions is..........
If I key on and let the pump prime and injector prime, then give the engine a very short burst of crank (short), then stop cranking and leaving the key on, then resume cranking it starts right away. This sounds strange but has worked well on various start-up maps I have tried recently. This morning I tried it on the cold start and it started right away. And it never starts right away when cold. What could this mean? What is happening when I do this? You would think it is just adding a bit more fuel but I have tested this with a bit more priming and it suffers.
Very strange and exhausted and frustrated with the months of tuning.

I would appreciate any advice as I am not sure how to move forward other than swapping the ECU and possibly the injectors and hoping for the best?

The history and the story............

I own a 92 Miata that originally had a 1.6 and have recently swapped in a 1995 1.8 with a Kraken Turbo Kit.
I am running the Speedyefi ECU with now the most recent firmware 2023.05
1995 1.8 Miata Engine with the 1.6 Electronics.
No crank wheel or crank trigger and uses the Cas for the trigger
I am using the 1.8 throttle body which is wired into my 1.6 harness
Cas wiring loom was extended.
Now wired for sequential injection and using Toyota Cops
Injectors are the Bosch EV14 700cc that came with the Kraken kit
Plugs are BKR7E gapped to 0.024
New DW Fuel Pump and filter.

As I am new to the tuning world I started out with the Speedyefi on my stock 1.6 setup.
I had a local dyno tuner come by and get it running and street tune the car and fiddle with some startup settings.
Car idled and ran fine but would not cold start properly.
Tuner was not interested in helping.
I researched and fiddled for weeks before I just gave up as I was going to swap the engine anyway.

I completed the swap with the turbo components and hired a reputable remote tuner to provide me with a full turbo tune.
This happened during the winter months here in Eastern Canada.
He got the car running well and did a short street tune out of boost to test my installation during the winter months.
Over the next couple of months I would log the cold startups weekly but was never able to get it to start properly when cold.
I must have received 15-20 revisions.
Back to the researching and I continued to try different settings and scenarios for startup.
I could always get it to start well when warm/hot but always struggled with first startup.
I spoke with different members and the guys at speedyefi for suggestions but had no luck.
Too much fuel would result in backfires and kickback or long cranking until it fired.
I settled for awhile on a setting and would play around each morning looking for improvement.
At times I would feel i was close but still had inconsistent cold starts and strange behavior.

After finishing the remote tune I still had a shitty starting car and mild misfires in boost at 5500rpm.
I swapped plugs, installed cops and converted to sequential injection not all at once but progressively.
I had some good luck running 2 squirts per cycle for the misfires before converting but then my idle was poor due to the large injectors.
Switching to sequential seemed to help with idle but still had some mild misfires in boost.

I then hired another remote tuner who was highly recommended. He has tuned plenty of miata's and speeduino ecus.
He has many years of tuning experience and an engineering background. Smart guy.
He took at look at my tune and log and stated that this tune was certainly not complete.
Hmmm. the last tuner has also tuned a ton of miata's and is even a reseller for the speedyefi. He is also a tuner by trade and has tuned many many miata's and speeduino's. Very concerning. Athough he seemed very knowledgeable I guess he is not as good as I thought or he just got busy or lazy.

The new tuner went to town on this map and we spent the next couple of weeks refining the tune.
He got this car ripping and running like a champ at 12psi with no hiccups.
In the end I still suffered from bad cold starts.
We spent another couple of weeks trying to get this car to start properly when cold.
Even a couple of 10 hour days straight tuning and trying everything but it still struggles.
I am certain he has tried every scenario?

I am not certain I know of everything he tried however I will try to mention a few.
He figured we were just using way too much fuel with the multiply map mode.
From the logs it would seem correct to use 2- 3 ms of prime and a lower cranking enrich.
This would start the car just not well or consistently and definitely not when cold.
In the end what seems to start the car best when warm/hot is a low priming pulse and about 120 cranking enrich.
These values are close to what I have been using in the past but cold start suffers.

Other things that have been tweaked are, cranking dwell, various IAC openings, different cranking angles including fixed, timing, ve idle cells, spark table, open loop and closed loop idle. Various tapers, tried keeping the IAC on for start.
I am sure there are other things that were tested that I am not aware of.
Various combinations of priming and cranking and IAC openings would start the car just not well or consistently when warm and not well when cold in any scenario.

I suspected something up with the trigger signal but seems fine in the logs and starts instantly when warm/hot with the current map. Unless this signal is weak when cold and just doesn't fire off the fuel quick enough when cold?

So I don't know if there is something wrong with my configuration or some piece of hardware but it is certainly not obvious. Once the car starts it is fine, it idles and runs great. I don't know if there is something up with the ECU as tuning doesn't seem to help or possibly these large injectors are not well suited to my application, or other. I am a bit past the point of testing with the stock ecu with many changes done. It could be done but is quite a bit of work.

So this is a bit of a long story however I think it may help understand the issue.

So currently I have a map on the car that does start the car somewhat decent and what I noticed in the last few days while playing around with the tuners map revisions is..........
If I key on and let the pump prime and injectors prime, then give the engine a very short burst of crank (short), then stop cranking and leaving the key on, then resume cranking it starts right away. This sounds strange but worked well on various start-up maps I have tried. This morning I tried it on the cold start and it started right away. And it NEVER starts right away when cold. What could this mean? What is happening when I do this? You would think it is just adding a bit more fuel but I have tested this with a bit more priming and it still suffers.
Very strange and exhausted and frustrated with the tuning.

I will add that I was running a map with 0.5 priming and low cranking around 70ish Cranking Enrich and it would start consistently both hot and cold but with long cranking times but no kickbacks or backfires when cold. This was ok for the cold starts but should start faster when warm/hot. I tried mixing the two tunes but couldn't find a balance. It would be strange to use less fuel when cold but I guess since it doesn't fire right way then with significant cranking it floods the engine.
It seems it just doesn't fire soon enough when cold without the start trick I mentioned.

I would appreciate any advice as I am not sure how to move forward other than swapping the ECU and possibly the injectors and hoping for the best?

See attached my current map and a couple of start up logs. One log is just normal hot starts and the other is somewhat of a cooler engine with the start up "trick"

Cheers

92Yata

So after re-reading my post I thought I would try the map I was using with lower cranking enrich and a bit more prime.
The car is warm but it also starts the car well when warm pretty well. This is closer to the fueling I should be using.
I will have to test again on a cold start but do have concerns as I have not had much luck there.

Here is the tune and startup log of this scenerio.
Started pretty well.
I use a bit longer of a crank to run taper because I was previously having issues with hot restarts after sitting.
This really helped with those hot restarts.

15 minutes later with this tune and trying to start the car is a big mess. Long cranking and some backfires.
See attached log. Endless loop

For those reading this for help, understand this tune is using the multiply map mode so less fuel is required for the cranking enrichment.

92Yata

Still fooling around with it today. Though after months I am tired of this game.
I feel as if the fueling is really close. It can start great when warm but not consistently.
I still find if I double crank it starts good almost everytime.
Again not sure why this is?
I opened the Idle screw on the throttle body and re-set idle to see if more air would help.
I did notice a few times where the engine didn't surge in rpm a bit as it normally would.
It still seems to behave the same.
Sometimes when I double crank on the first crank it would seem to turn off the fan but not always?
When I say double crank I mean a very short burst of crank to start and then resume cranking.
Fuel pump shuts off on the first crank too. Maybe this is normal
I have attached my map and another log of a few starts when warm.
First start was instant. Second start fumbles a bit and the 3rd started ok with the double crank "trick"

Just some more info in case someone has some idea as to why?

92Yata

I am still playing with different fueling for prime and crank.
Tuner already told me I was using too much cranking fuel but it just seemed to start better this way especially when hot.

But the logs dont lie.

So I lowered the cranking all the way down to like 20 and started to work my way up with the priming at 3.0 when engine is at temp.
Tuner figures the priming should be around 2-3 and to keep the cranking as low as possible.
So I ended up at around 60 cranking enrichment at hot.
I did get a few good starts this way without the double crank trick.
I will save that trick for the cold start :-)
Here is the tune and log of this.
I have had enough after three consecutive days of playing with start up.
I have a few maps to experiment with and need to put them to the test.
I am now doubting that I will ever get consistent great starts.

92Yata

Well with persistence and the heavy testing this past week. And with more thought on the history.
This car just needs more fuel to start.
I have tried what is supposed to be the correct fueling for startup and it is simply not enough.

I understand that in a multiply map mode tune that the fueling needs to be 100% less when cranking.

I have just simply started bringing up the the priming and cranking until it will start well.
I started low at 20% and have worked my way back up to 120% cranking enrichment when hot.
The car starts well this way.
Although I am told this theoretically this is too much. The car simply needs these values to start.
The only thing I can I can guess is with these large injectors and the low pulse widths and lower voltage while cranking its not actually injecting as much fuel as I think or the ecu is not calculating properly.
The double cranking just must have been giving it more fuel before starting.
The only time I have the car start well is with higher fuel values in the priming and cranking enrichment and a larger IAC value.

For the so called heatsoak issue at the injectors or rail and is not IAT related...well simply put ...I am told there is no such thing.
Also I am told dont worry too much about your AFR at idle as its not an accurate reading anyway. Sensor and piping is all cold. Its more about the map readings (kpa values.)
Dont use your ASE to correct it ...well maybe you can use a tiny bit for a short period.

Use the crank to run taper. Increase this value to like 8-15. And bring up your IAC cranking value so it does not rev hang too much. Play with these values until your satisfied.
Even on a stock miata RPM will rise to around 1500rpm on startup for second or two before settling.
This can only be used in Open loop idle.
I have requested for this to be added to the closed loop idle in the speeduino forum.
MS has this feature in closed loop as well.

Here is my last tune with more priming and more cranking enrichment.
Car starts. I might even need a bit more fuel.
I am done fighting this issue. I am just giving the car what it wants. What I hear and feel.

92Yata

This was my first time playing around with a tune.
I had not planned on learning too much as it is a steep curve.
I had hoped my tuners would have got it done for me.
I ended up learning a ton....and am glad I did.
I could have passed on the months of shitty start-ups as this was frustrating.
If I had to do it again I'm sure it would go smoother.
The car needed to be tuned well by these experienced guys anyway before refining startup which it was.

I just needed to settle on a priming amount and then start low on the cranking enrichment and start working my way up until it had the fuel it needed to crank to run with little effort or cranking time.
When I saw the amount of cranking enrichment used on the MS base tunes I decided to try much more.
Earlier when I was experiencing backfires and kick backs was because it had only just enough fuel to make me think there was tooo much when in fact in needed more.
Lesson learned.
I do hope others can benefit from my story.
I have had a few more great cold start-ups and am happy to put this to rest and enjoy the car.
Cheers !!

92Yata

So to follow up on this post. I finally gave up on the Speedyefi and bought an MS3Pro.
The car was running pretty decent on the SpeedyEFI but would never cold start properly.
It would always start just not well. Tuning in boost was a real pain as well.

Problems solved with the MS3Pro. No more cold start issues no more misfires, no more problems tuning in boost.
Some people may have luck with the SpeedyEFI units but I did not.
Almost a year of tweaking startup settings...I paid 3 different tuners...until I threw in the towel.

Cars tuned well now on the MS3pro at around 13 psi probably around 220 hp. Starts as it should under all conditions.

I have attached some files.
My last map when using the SpeedyEfi, my current map on the MS3Pro and the last datalog pull when tuning,

Here is a view of some data entered into Virtual Dyno

Z_WAAAAAZ

Have a cat for following up and giving the cause/fix of your concern.

+1 on the board for Megasquirt.

DNMakinson

iTrader: (3)

What turbo?

der_vierte

2560R

92Yata

Correct.... It's a T25 Garrett GT2560r
Kraken Turbo Kit