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-   -   DIY MS3x hitting limiter 2000 rpm? (https://www.miataturbo.net/megasquirt-18/diy-ms3x-hitting-limiter-2000-rpm-98657/)

acey 12-02-2018 06:46 PM

1 Attachment(s)
So I went and did some tuning to the VR pots. This is for sure the issue! I was able to get the car revving freely.

After messing with the pots I was able to get the car running all the way up to redline. But I am still having some weird behavior as my tach in car was readying 7000rpm and now as I look at the log I am seeing 7800rpm. My hard limiter in tuner studio is set to 7200 so I don't know how or why it was able to climb this high. Or whats causing my tach and tuner studio to read a differential RPM. After adjusting the pots the car was having trouble staying running on its own. 4.8v on R11 and 1.1 on R56 is where both pots current sit at. This is significantly different than the 2.5v specified in the Manuel which throws me off. Is there a better method I should be using to tune these pots other than guess and check?

Big thanks to everybody who has chimed in thus far. Hoping to gain a bit more understanding of this before I continue or potentially damage anything. Here is the log I took while adjusting r56 where the engine gets to a alarming 7800rpm. My VE table right now is a joke, I haven't really touched it since I have been focusing on this issue. So AFRs are kinda all over the place.

gooflophaze 12-02-2018 07:23 PM

You have a hard rev limit set, but no method as to how - you haven't enabled spark or fuel cut.

And the stock tach is pretty inaccurate.

acey 12-02-2018 08:08 PM


Originally Posted by gooflophaze (Post 1513168)
You have a hard rev limit set, but no method as to how - you haven't enabled spark or fuel cut.

And the stock tach is pretty inaccurate.

which is better or more commonly used. spark or fuel cut?

SpartanSV 12-02-2018 08:19 PM


Originally Posted by acey (Post 1513172)
which is better or more commonly used. spark or fuel cut?

Your basemap had it turned on. Maybe you should look at what it used......

acey 12-02-2018 08:24 PM


Originally Posted by SpartanSV (Post 1513174)
Your basemap had it turned on. Maybe you should look at what it used......

oh... duh. thanks

gooflophaze 12-02-2018 08:24 PM

Fuel cut - possibility of lean condition as you're bouncing off the limiter.
Spark cut - possibility of backfire pop when the spark comes back on.
Retard - high cylinder EGT's.

Pick your poison. I ran spark cut without a cat.

acey 12-03-2018 08:03 PM

Problem is officially solved. The issue ended up being incorrectly tuned VR pots. As I mentioned above both r11 and r56 had to be moved pretty far from the documented turns specified both on trubokitty and the megamanuel. Big thanks to all of you who have responded to my dumb questions. Now onto tuning!


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