MS3 Mini needs a lot of fuel to run
 

Hi, I have installed a MsLabs MS3 Mini (v3) in my stock (other than a header) 1990 Miata. I am running into a strange issue that I cannot seem to figure out. Starting off with the base map with the base idle set, the car will struggle to start, and when it does, the slightest touch of the throttle pedal will cause the engine to buck and shut down. I noticed that my AFR (AEM UEGO) was going crazy lean whenever this happened, so I tried adding more fuel until I got the car to start easily. This worked perfectly, so I took the same approach for the bucking when the throttle is pressed, and added quite a bit of acceleration enrichment. Again, this worked perfectly and got the engine to run relatively well, so much so that I have been using this tune daily for a few weeks now. The only issue is that at times (especially during the first few minutes of running) when coming off stops I do notice some hesitation/bucking. It’s not bad enough to shut down the engine, but the AFR shoots up to 17-20 on these occasions.

While the car is usable, the VE table I have to run is very rich and doesn’t really make sense, and even though the AFRs are decent (although they don't really hit the AFR target) and it feels like I’m compensating for either a hardware issue, or another issue on my tune. Whenever I reduce the VE cells by 10, the car starts running very roughly, and reducing them by 20 will shut down the engine.

Thing’s I’ve checked:

• Fuel pressure: maintains a constant 40psi. Clamping the return puts it up to 70-80PSI, so the pump seems to be fine as well. The engine also runs perfectly at high RPM.
• Vacuum leaks: Using a smoke machine, I didn’t notice any smoke coming out of the engine bay.
• Used custom IAT instead of the AFM IAT
• Changed injector deadtime to 1ms from 0.9ms: didn’t make much of a difference
• Changed injector size to 230cc and the required fuel to the calculated 11.7: did not make a massive difference, if anything the lower required fuel made the problem more noticeable.

Does anyone have any idea as to why this might be happening? I have attached my tune, and also a screenshot of the VE table (might be slightly different than the tune as I don't have the latest screenshot) if anyone wants a quick look.

Thanks in advance.

https://cimg9.ibsrv.net/gimg/www.mia...6021a147a8.png

First, go to the "Meet and Greet" forum and introduce yourself. Otherwise, you may not get any answers. It's protocol--they're not being complete assholes.

You need to post a log. Without a log, it will be difficult to do any diagnosis.

I'd say you're worrying too much about the numbers in the boxes in your VE table. That said, the tune you posted shows your injectors are set at 190cc. I believe they're bigger than that. Peruse this thread, especially Post #18. https://www.miataturbo.net/megasquir...ettings-31877/ (I don't understand why anything but 14.7 would be used as the AFR in the Required Fuel calculation unless you're running something besides normal pump gas, since you can use whatever you want in the AFR Table).

Your AFR table goes rich very early. I have a Rotrex in my track car pushing just shy of 10 psi and I don't start going richer than 14.7 until 90 kPa.

WTFuck does this mean? Vacuum leaks: Using a smoke machine, I didn’t notice any smoke coming out of the engine bay.