High Positive STFT spikes on throttle lift-off

[smdarmon]

2023 Civic SI, 12,000 miles. I have a TSP-Stage 1 tune, typically run map 1 or 2. Shortly after installing the tune and monitoring, I was noticing fairly high positive STFT spikes off-throttle in excess of 20%. I did a once over the car for vacuum leaks and cleaned the MAF with no change. I had a K&N typhoon intake, and after seeing the step in the air pipe right after the MAF, I assumed this was contributing to some of the issue as I have up to 6% STFT correction at idle that will increase the LTFT if left to idle. As I would drive, the LTFT will equalize out, typically around 1-3%, but I've never seen it trend zero. No real driveability issues, so I have accepted for what it is and have been monitoring here and there with tunerview.

I since replaced the intake with the PRL HVI stock-MAF unit with a PRL Turbo inlet pipe. This does not appear to have changed this trend. I've walked the car up and down for vacuum leaks, and replaced the vacuum hose clamp the rear of the valve cover as this hose was fairly easy to pull-off but I couldn't verify a leak. This appears to be present across several tunes on the Ktuner platform on my car, including the stock one. I have not yet tried a tune with rev-hang re-enabled yet. I have attached two data logs, one from april, and one from today. The april log was with the old intake (50F outside), and today was with the new one (87F outside and humid). I've never seen STFT spike this high on other cars that I have owned, but I am also not sure if I have datalogged to this level of resolution, either. I would appreciate another set of eyes for those willing to take a look.

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[fenix-silver]

Sounds pretty normal to me. On my 10th gen Si, the STFTs would spike into the 20s. As long as your LTFT is around +/- 5% (i think mine sometimes hovered around -6% with the TSP Stage 1 tune) and you don't see the STFT spike to +/- 35%, which IIR is the max, I'd say your car is running perfectly fine.

 

[V3N0M_VZL4]

I were having the same question, and I contacted the guys from tsp and they said that is pretty much Normal as long as the LTFT trend to 0~3%, 8 upgrade my map to the latest one btw and with more time driving has been improved the STFT spikes, for how long the map has been running in your car?

 

[Two Step Performance]

This is standard behavior and there is nothing changed in the tune that would impact fuel trims.

 

[smdarmon]

I appreciate the feedback. Overall, as I have driven the STFT spikes seem to have settled down. I just didn't have a good stock baseline to compare to since I purchased the car with an aftermarket intake already. I took both logs the same day after an ECU reflash. I did want to point out with the PRL intake my IATs do trend a little closer to ambient than the K&N Silver Typhoon so that is encouraging.

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