VersaTune User Forum

^ that. I've installed the tune like 1 month ago, drove the car for a good 300-400 miles, and I get nothing but 0, no matter of what. What could it be?

I changed the MAF for a new one at the start of the year(stock MAF), changed the precat o2 sensor 4 months ago (stock).

I'm on my phone here so I will be brief.

There are several areas where the RX8 ECU builds long term fuel trim.

It is not necessarily a bad thing to have zero LTFT. People will often try and achieve 0% LTFT at idle.

Some keeners try for the entire Maf/Load range.

In short it matters where you are looking at the LTFT. Are you looking at the idle LTFT?
This would be good then.

Often the other parameters used when evaluating LTFT is STFT, Maf g/s or volts, RPM, and LOAD.

If you could provide a bit more detail and or a log file would help people answer your concern.

On the surface tho I am thinking ok no problem what's the concern? Zero is good right. Why do you think it's not?

Post a log.
If the STFTs are lower than -20 or higher than 20 then the LTFTs won't learn.

mituc wrote: ↑August 22nd, 2024, 4:24 am Post a log.
If the STFTs are lower than -20 or higher than 20 then the LTFTs won't learn.

Indeed. STFTs are actually min -12 max 9

mituc wrote: ↑August 22nd, 2024, 4:24 am Post a log.
If the STFTs are lower than -20 or higher than 20 then the LTFTs won't learn.

Nvm, solved. I don't know how, but after so much driving, the fuel map wasn't ready yet. Now it reads both LTFT and STFT.

0124alexrx8 wrote: ↑August 26th, 2024, 6:49 am I don't know how

The defect is still there, you just got lucky getting the fuel trims below the threshold above which the ECU does not learn.