Crank but No Start - Mx5 NB1 Boosted

[BeefNugget]

Here's a log of the idle. It's strange, it idles nicely on startup, but after any throttle input it then idles at 1500rpm. 

Sorry it's not letting me attach files. Says there is a 17 kB limit?

[Adamw]

You have used up your allowance, you can share a link using onedrive, google drive, dropbox or similar.

[BeefNugget]

Ah ok. Heres the log. https://drive.google.com/file/d/1UYf-DReYX76JPRl-CaXaZXnP9VO58_3l/view?usp=sharing

[Adamw]

The link is restricted, go back into the sharing settings and set it to "anyone with link".

[BeefNugget]

Ahh sorry, should be fixed now. 

[castillaricardo]

On 7/14/2023 at 9:11 PM, BeefNugget said:

Thanks for taking the time to write this all up.

So it looks like my car matches the first pic (Return system) so does this mean MAP referenced was the correct setting.

Also, I do have the exact same setup as prev owner as I bought everything off him, so boost control setting should work but I'll follow your advice anyway. When you say change it to 0hz do you mean the PWM freq, cause if so it says the min is 1. Also not quite sure if I set the MAP limit correctly, I've attempted to set it to 10 in my tune. 

 

For the fuel cut table I have it changed like so:  Is this what you meant?

And yep totally agree about wideband setup. Currently have one installed and showing on a gauge but will be wiring it to CAN hopefully soon (Do you know where to get the connector for the board from I'd like to solder up my own connection but cant find the right plug).

So I've made all these changes and now the car won't start. I'll attach the log (EDIT: REMOVED LOG FOR UPLOAD SPACE).

Attaching the updated tune if you need it.

 

Wait, I had the MAP limit at 70 kpa not 170. Now it idles properly.

Yes, MAP referenced is the correct setting then. I don't know what the fuel pressure is on those, maybe Adam or Vaughan know or you could look for a service manual that fits your car.

About the boost control setup. What I meant is that you should set the Wastegate %DC 1 table to all 0s until the fuel map is tuned.

Yes on the fuel cut table.

Do you have a Plug-In NB1 G4X? If so, this is the cable you'll need for CAN: https://dealers.linkecu.com/CANJST4. Pinouts are on the site and Help page.

I think you have a vacuum leak, your throttle is not closing fully, or your idle valve is not closing enough. Your idle valve at one point is at 0% duty cycle which should have stalled the motor but it is getting air from somewhere. The extra air is making it idle too high after you blip the throttle and that's why it isn't entering into the closed-loop idle after (Idle Status hangs at RPM Lockout).

Also, add your current tune to the Google Drive link.

[BeefNugget]

Ok great.

The wastgate %DC 1 table is zeroed out so all good.

Yeah I saw that CAN cable but would rather solder up my own. But not having any luck finding the right connector on its own for a reasonable price.

I'll spend some time looking for a vacuum leak. Do you have any tips on narrowing down leaks.

Heres the tune: https://drive.google.com/file/d/195_rv5IHWPybjwFiKjMoN6lPAehE9Z42/view?usp=sharing

[Adamw]

Can the throttle stop not just be closed a little more?  The idle valve is fully closed so the ecu cant bring the RPM down any more.  The cause of the "RPM hang" is at the beginning of the log you have idle ign active so that is pulling the RPM down close to target, after you blip the throttle then idle ign is disabled, the idle valve is already fully closed so the ecu cant do anything further.  

The connector on the CAN cable is a JST XA series.  

[koracing]

JST XAP-04V-1 for 4 pin CAN expansion

JST XAP-05V-1 for 5 pin CAN expansion

JST XAP-08V-1 for 8 pin I/O expansion

pins: SXA-001T-P0.6

[BeefNugget]

Ok, so I adjusted the throttle stop, and that seemed to work. As I turned the screw, it suddenly dropped to the correct idle, idk if that's normal. Also, it would then idle again at ~1500 randomly, and if I adjusted the throttle stop a little, it would then drop right back to the correct idle speed. 

Also, I took it for a test run around the block. It seemed fine, but there was a strange deep vibration on deceleration. Does this show up in the logs? Because if not, it might be exhaust vibration related, as my new exhaust sits very close to my diff.

Attaching the log and tune: https://drive.google.com/drive/folders/1wmVdAF2qSn2iotbbZbv8TZb6H3jt7EtD?usp=sharing 

[Adamw]

Your problem now is now just tuning.  Your log shows you need 21.4% idle position to idle at the target speed, however your base position is 25% and you also have a dashpot offset of 5%, so as soon as you touch the throttle the idle vale opens to 30% which is too far open to allow the RPM to drop back under the lockout.  Set the dashpot to zero initially, follow the instructions in the help file to tune the base position, then experiment with the dashpot if you have undershoot entering idle conditions.  

[BeefNugget]

Hey guys, so I've wired my lambda sensor up and the readings are the same on the gauge, so all good there.

Here is a log, the car seems to be running rich (upped the injector to 1000cc from 700cc which helped) and there is the occasional stumble (once every 3-5s). Kind of feels like how a big v8 will lurch on idle. What can you tell from the log?

https://drive.google.com/drive/folders/1YUaQM-q8ER3SZmmzc-I7WI8x9VaOY5Yy?usp=sharing 

[koracing]

I don't see anything jumping out in the log that looks like a stumble.  I would try reducing the idle ignition control derivative to 0.  I would turn on closed loop and see how that feels at idle if it makes a difference.  Your fuel model value for the engine displacement is 1800cc when the BP Miata enigne is 1839cc (83mm bore and 85mm stroke).  Your differential pressure is listed as 260kpa - have you actually measured your fuel pressure at the rail?