Have been fine tuning for the past week or so with the Brain built MS3x, and have it running quite well so far. However I still have a crappy crank/startup that I can't seem to figure out.

Mostly when cold (first start of the day, it doesn't get "cold" in Florida) I crank it over, it seems to dip a few times and then starts and purrs. Some days it even sounds like it "locks up". The motor stops turning for a second, I let off the key, and try again and usually it will start right after that. Almost as if the battery is bad, but the initial crank isn't sluggish like it is with a weak battery. OR sounds like it is flooding, but I have pulled plugs immediately after that and they are not wet with fuel. Giving it throttle will "help" but it still will be a rough start.

In the logs, you can see where the RPM flatlines and kicks back up again.

I tried it with a 60A boost charge and it did the same thing.
I tried adjusting the Cranking pulse: more fuel, less fuel, default set by Brain and, can't quite get it right.
I tried more and less idle cranking duty steps.
I tried more and less cranking advance (have it now set to 0, the more the advance the more it struggles. Maybe try setting to negative to make it retarded? Doesn't seem right, everywhere I read says it should be slightly advanced)
I upped the cranking RPM to 700 (if it is lower, it gets worse, I think it goes in to "run" mode too early)

I did have hard time setting base timing (see last post here for what I had to do https://www.miataturbo.net/megasquir...ew-ms3x-80684/ ) I check timing with a light when its running and it looks pretty spot on with what the advance says on TS.

I have not messed with Priming Pulse or other ignition/dwell settings other than "cranking advance" under the ignition options. Cold advance is set to 0* from 80*F and up. Other than those, I don't know what else will effect cranking.

Here is an example. Wasn't too bad this particular time but you can see it's not quite right. This was with the battery charger attached:


This is another, without the charger. Sitting after 11 hours at work (BattV about 11.5 or so):


Attached is a handful of startups and my current tune.

I appreciate any help.

Edit: the only thing that I changed physically on the car was the factory ECU. Prior to the MS3x, there was no problem starting.

Edit 2: each log may have different settings at that particular time. If you see a log that shows something you like, I can try and look back at the restore points and see what I did that day to the tune settings.

Thanks,

Andy

 

are you using stock injectors with a deadtime of .800ms? that's not going to work very well. you'll probably want around 1.2 and readjust your deadtime curve

 

Stock injectors yes, and the dead time/curve is the default and was set by Brain.

I will try 1.2, however I did read MegaSquirt-3 Fuel system and it suggests .8 to 1.0 for high impedance injectors...

I really don't know much about dead times... In my case, I'm assuming I should adjust the curve below 13.2v, but should I be adjusting the percentage higher or lower than it is currently?

 

use 1.2ms for stock injectors. .8-1.0 is way too low for the stock injectors. even my ev14's use .983, and they are much much faster than stock injectors

make sure you're entering in the correct cc for the correct stock injectors and not just some random number for the REQ_Fuel

With your deadtime going up, you'll probably get values in the high 30's/low 40's in your fuel VE table instead of what you have now

try a dead time curve of:

voltage:----------%:
8.0----------------160.0
10.0---------------133.0
12.0---------------109.0
13.2---------------100.0
14.0----------------91.0
16.0----------------70.0


unless of course Brain has updated the curve he used to use in his older posts


just looking through your tune. Your rev limiter is quite low

also, your afr table goes up to 400 kpa... that's 42 psi, you my man are crazy :P

your fuel table also goes up to 400 kpa....

 

Req fuel and all that is default. Looking over it, I see it is set to 260cc (99-00 is 240cc I believe) I will adjust that.

I haven't seen many others' VE tables, but from the ones I have seen my values do seem higher.

Current curve is

6.5----476
7.8---320
9.0---236
11.5---136
14.0---84
16.5---44

Rev limit to 7300 is low? I try to be somewhat respectful to this ol thing, 153k miles lol

And the AFR and fuel tables are set by default. I am NA right now (and for a while). I guess it wont hurt to rescale them down. Any sense in having the max above 100?

 

7300 rpm is fine, I'm probably just loading your tune with an old firmware, which is why I'm seeing weird stuff

99 injectors are 256cc

do not rely on default settings. there are no default settings.....

 

I see... our wiki says 256cc

Fuel Injectors - Miata Turbo FAQ

But I do see quite a few threads stating that they are 240cc @ 43.5 psi.

https://www.miataturbo.net/diy-turbo...big-post-4288/

Maybe it's closer to 256-260 @ 60 psi?

If there is any other information that is unclear due to older firmware, let me know and I will confirm. I'm really trying to sort this out.

And by default, I mean that I gave all requested info to Brain, and whatever he loaded in there as a base tune.

 

And by changing the dead times, it looks like I'm going to have to completely redo my VE table?

Might as well rescale the kpa down on both tables and completely start over.

I so hope this works....

 

The base tune that came with my MS3 basic has my injector size listed as 254's. I also have the same issue when starting/cranking.

 

I would do one simple thing first before making any changes. Try changing to "alternate events" for "priming fuel pulse". And put cranking rpm back to 300 as no engine cranks at 700 rpm.

I compared your settings to mine and they are very close other than that. Since I live about 20 miles South of you and my car starts fine, I would say you are adding too much fuel if injecting at every event.

And I would use 300cc for the injector as thats what you are actually using. Technically 311cc according to the math.

And 1ms for injector dead time.

 

How do your tables look compared to mine?

I'll try these small changes first and see.

Are you recommending changing the injector size in the req fuel calculation?

 

Yeah but do that after or if you wish, dont do it at all. You already have the capability to adjust your VE and countless other fuel settings so getting the injector size spot on isnt so critical. Every bit helps though, and telling the ecu as much truth as you can is better than fudged up numbers.

Oh, and our tables look very similar. Im running MS2 though so you have many more settings than I do but the 2D tables are on par.

 

yes your problem is .8ms deadtime on 240cc ev6 injectors.



or maybe fine tuning all startup enrichments and parameters could help.

 

Also, you have "batch fire during crank" set to on. TS says thats useful in cold climates for getting more fuel into engine during crank by running batch instead of sequential(duh!).

Between that and getting fuel into the engine every time there is an ignition event, you may be easily flooding the car on crank in our climate.

Try changing one or the other or both and see what works best for you.

I dont know how mine is set up, batch or seq, but like I said it starts fine in our climate. Cant say how well it would do in cold weather.

 

This is with crank rpm at 300 and alternate event priming pulse. You can hear the relays clicking and TS shows "fuel cut" when they are clicking.

 

So that was the worst start up by far.

Go back to the settings in start up 1, and turn "batch fire crank" to off.

If that doesn't help, maybe you are on to something regarding your ignition but it sure sounds like its fuel related as far as the rough start goes. The kicking back sounds timing related though.

Assuming you have stock ignition, DIYautotune suggests cranking dwell of 7.5ms and max or nominal dwell of 4.5ms and spark duration of .7ms. You are at 6, 3, and 1 .

Also they show 10 degrees for cranking advance but you sound like you are too advanced at 0 just guessing by the sound.

 

This is with 15* cranking advance, batch fire cranking off, pulse rate is every event (not much difference vs alternate), and crank rpm at 350


I currently have Coil On Plug & Ignition : Fab9 Coil On Plug PNP Conversion Kit running wasted spark.

 

OK, we have the same coils. Mine are being run by drivers inside my ecu and full seq but the coils are the same. My settings are 4.5ms cranking dwell, 2.5ms nominal dwell and .7ms max duration.

Since that last attempt sounded a lot better than start 3 and somewhat better than start 1, maybe try fuel settings in start 1 and keep 15* and the ignition settings I use. Maybe its ignition related all along.

 

It sounds to me like I'd be increasing the cranking PW a bit. Those startup tables are very generic and need to be fine tuned per install.

 

Since the engine is hot now, cranking pw% at 180* is 100%. If I go higher it gets worse.