MS3X NB2 above 2K rpm issues
 

I made a post a couple weeks about some idle issues that some users helped me fix in my NB2, but I'm having weird issues with the engine above 2k rpms where it sounds like a mechanical rumbling or knock noise similar to a diesel engine. The ECU is a MS3X built following Braineack's spec, with a AEM X series wideband. Everything else is stock in the car.

Some possible causes that I have tested was non firing spark or injectors, but I tested both and they work OK. For the spark plugs I pulled all of them and ran an output test mode for which they all sparked fine, and then I used the Inj/Spk disabling test mode while the car was running, disabling the coils and injectors one by one while revving to 3K as that's where the issue occurs. When disabling any of the coils/injectors the motor shaked far more than normal leading me to believe that it's another issue. I haven't been driving it at all in case the problem is knock or something else which would cause the engine to deteriorate.

I made a video recording the problem along with a playback of the log side by side. I was flooring it for a while and you can see it is like it hits a rev limiter of 4300 RPM. Acceleration is also half of what it was before running a stock ECU.

Here is another clip revving the motor in the engine bay

You can also check out my tune which is only lightly modified mostly in regard to the idle settings from truboKitty's, and the log. Thanks!

I don't know if I'm much help because we both have extremely similar issues getting our NB2's going on the TruboKitty base map. I've got a fairly lengthy thread going where I've been fighting the same thing. I was able to "fix" mine by pulling a lot of fuel and it was able to rev past 4.5k, but something still doesn't seem right at all. I've actually tried driving mine since my AFR's looked respectable but no matter how much I've tried adjusting my VE fuel tables It's slow as mud. I can't get a solid answer if the timing map for NB2's is just massively conservative to the point it's causing these problems or what. I'm also running an AEM-X series wideband if that helps. For the record my thread was mostly troubleshooting hardware since I bought a dead MS3X by mistake so you can ignore a good chunk. How well does your car start? My "hi res polarity cam" had to be switched from normal to inverted for it to start normally. It's interesting yours is different. Again, please don't look at me as an example because I'm having just as many problems as you are, but maybe the collection of data can help figure it out. Here's my thread: https://www.miataturbo.net/megasquir...x-94637/page6/

Switch that, it started better on "normal" instead of "inverted"

We figured this out. VTCS wasn't opening and our cars were being forced to breathe through a straw 100% of the time. Anyone following this can look here for more details: https://www.miataturbo.net/megasquir...x-94637/page6/

Yep like ungluedflyer said, VTCS was certainly incorrectly set up in the base tune. I still have to try out some of the other advice he posted in his thread like setting the cam to 'normal'.