VersaTune User Forum

Dear everyone using VersaTuner,

Hello there! I’m quite a noob in this world, but I’ve been having a headache diagnosing power loss above 5k rpm. The issue with this is that it is intermittent, so I have never been able to truly diagnose the problem.

At first I thought the mx5 things roof controller was causing this, because it hasn’t happened again since I uninstalled that. But it recently started happening again, and I’ve been logging the same thing. So maybe it’s something else? Whatever it is, this thing is really inconsistent making it an absolute pain to find what the issue is.

I can share the CSV of a log I pulled where you can clearly see relative throttle position closing from 100% to roughly 30%, which results in a complete lack of power and a complete loss of chair pushing in your back.

Can anyone please help me find out what this might be, or at least give me a couple tips of what to log further? This problem really has been a thorn in my fun and makes me worry about the car.

It’s a 2020 RF and the problem appeared in the98 RON, 95 RON OST AND stock tunes. Even a complete VersaTune uninstall had this occurring, meaning it’s not the tune which is kind of a bummer because that would be an easier fix.

If anyone would like to help me and needs more information to do so, please ask and I will oblige.

Log CSV attached.

Kind regards,

RustyDusty

Can you take a similar log but also log the control module voltage?

How many miles on the car?

You're MAF signal is very messy.. Do you have an intake on the car or is it stock? MAP signal is also a bit messy.. Sometimes this can indicate a miss fire. You're also knocking right from the get go..

Can you add control module voltage, and Fuel trims to the log.. You can remove HPFP, intake and exhaust cam advance data, intake air temp, and coolant temp.. This will help with logging resolution.

CrazyCanadian wrote: ↑December 11th, 2025, 2:02 am You're MAF signal is very messy.. Do you have an intake on the car or is it stock? MAP signal is also a bit messy.. Sometimes this can indicate a miss fire. You're also knocking right from the get go.. .

A misfire will not affect the MAF sensor readings, only the O2 readings (and then as a result also the fuel trims).
As for the jumpy MAF signal... this is how it looks on pretty much all these skyactiv engines.

Thank you for the quick responses!

Interesting that the MAF sensor graph is supposed to look like this for skyactiv.

I bought the car in February with 149k km and I’ve driven it so far to 167k km which would be roughly 104k miles.

I’ll try to trigger the condition again today and add the control module voltage.