Old Firmware vs New Firmware and Tunes: NO AFR.
 

I've posted build stuff for my turbo Miata-based Lotus 7 a few years ago.

I started this project in 2006, and had it registered and VIN'ed in 2011. Switched over from N/A to turbocharged around the same time, if not a little earlier. I forget. My dad built a MSIII (new at the time), because, if I remember correctly, MSII didn't have EBC options. It ran OK, using a combination of a tune from miataturbo.wikidot.com, and VE tables. Foward to 2018. It hadn't been driven for a bit, and suddenly, when I run it, it runs ok at idle and cruise, but falls on its face when using throttle, i.e. when it would be using the o2 sensor/AF. I tried a new sensor, nothing. Checked to make sure there was conductivity between the o2 sensor and the ECU, nothing wrong there. I recently pulled out the ECU and gave it to my dad, and he went over it, checked everything, ran it using the JimStim, no problems, and there was an o2 response.

He came over yesterday, and I put the ECU back in the car. The firmware was old, and he originally flashed the new firmware, but that made the old tune non-functional, with several pages of errors. When I'd start it, it'd idle like crap, and sound like it was running on 2 or 3 cylinders. We backtracked, and reflashed the old firmware, and the old tune. It'd start just fine, and idle ok, but as before, when under throttle, say 75%, it'll start to stumble. Still no AFR gauge readout in TunerStudio.

We reflashed to the current firmware, and tried to convert the old tune to the new firmware. It still idles rough, and while the o2 sensor is showing something, I am not seeing any AFR gauge options in the new version of TunerStudio.

I will upload and attach everything I have right now. I have to dig to find the old logs, when the car ran right, but I will find them, as a baseline.

Can anyone help figure out A) how to convert the old tune to the new firmware, and B) why it's not running right, after running perfectly fine for years.

Thanks.

https://drive.google.com/drive/folde...2M?usp=sharing - This has two folders, Old Tune/Firmware, which includes up to last year (some of the datalogs there will include the current issue), and New Tune/Firmware, which includes the latest firmware and the error-filled tune. It also includes a quick log of it idling and revving. It was rough enough that it was not worth trying to move on it's own power.

Your latest tune has no idle control valve

https://cimg1.ibsrv.net/gimg/www.mia...83c51ed46b.jpg

o2 sensor should have no affect at 75% throttle. Your tune needs to handle that. Post a log of it running like crap. It sounds to me like your map line is damaged or disconnected, or the map sensor is bad.

IAC valve was deleted. How does that translate to the new map? Curly, the latest log was of it running the new map, like crap, if I remember correctly. I believe my dad will join here and give better in depth of what is going on, but one of the biggest issues that we need help with is converting from the old tune to the new. A lot of things have been renamed, and inputs may be all out of whack because of it.

(Nathan's dad here -- the builder of the Megasquirt. I know how to make computer chips, but not much about Miatas or turbo.)

BTW, this engine came from a 1996 Miata, but it is installed in a home-built Lotus 7. The engine, trans, and rear axle are from various scrap Miatas, the steering is from an MGB, and Nathan built the rest from scratch.

I built the Megasquirt 10 years ago. It's a MS3, not MS3X. When I tried to remember why I built it the way I did, it was a bit of a problem, because much of the information I used back then has disappeared from the Internet. Also, no one seems to use plain MS3 any more, it's all MS3X or PNP. The best reference is my posts in this forum from 2011 that I just now re-discovered. (https://www.miataturbo.net/megasquir...k-right-62430/)

When I tried to resurrect the ECU I had to install a new copy of TunerStudio, which seemed to want new firmware, so I upgraded the MS3 firmware. When I re-loaded the tune he had been using there were a lot of error and warning messages. The firmware changed a lot in the past 10 years. Some of the parameters have been renamed or greatly expanded. At this point I think the best thing for us to do is get a fairly vanilla Miata tune from someone using the new firmware, and start over. The old firmware was version 1.0 something, the new firmware is 1.5 something.