Fuel trims swinging wildly rich at 0° VTC

K-Series Programmable ECU installation questions / support issues
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Ecky
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Joined: Sun May 26, 2019 11:35 am

Fuel trims swinging wildly rich at 0° VTC

Post by Ecky »

I have an issue with my fuel trims swinging wildly rich at 0 degrees VTC. Attached are my kal and a log.

Last year I meticulously corrected my fuel maps, such that they were generally within 1-2% in all cells at all cam angles. This summer I've been playing with different cam angles at part throttle, chasing fuel economy. I've noticed that at 0 degrees VTC, something weird happens that I had not observed at 10, 20 or 30 degrees: I can be driving along at a steady speed, and randomly the AFR will begin to drop, to the point that my fuel trims max out and AFR starts swinging rich. I've seen AFR drop by more than 20% with no noticeable changes to any other sensors. However, if I toss it in neutral and blip the throttle, it will return to normal for a few minutes.

In the screenshot below you can observe this.

Image


Is this possibly the evap system feeding fuel vapors? I can't think of anything else that would cause it.
Attachments
TSX v4.2 91 octane ethanol free-200730-002.kdl
(4.54 MiB) Downloaded 134 times
TSX v4.2 91 octane ethanol free.kal
(164.61 KiB) Downloaded 113 times
Ecky
Posts: 22
Joined: Sun May 26, 2019 11:35 am

Re: Fuel trims swinging wildly rich at 0° VTC

Post by Ecky »

Verified this morning, it doesn't happen with 10 degrees of cam advance. Fuel trims stayed right where they were supposed to, rather than drifting wildly like they do on 0 degrees.

This morning:
Image

Yesterday:
Image
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Spunkster
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Joined: Fri Sep 20, 2002 5:06 pm
Location: Hondata

Re: Fuel trims swinging wildly rich at 0° VTC

Post by Spunkster »

Are you using live tuning, and if so what tables are set for live tuning?
Ecky
Posts: 22
Joined: Sun May 26, 2019 11:35 am

Re: Fuel trims swinging wildly rich at 0° VTC

Post by Ecky »

No live tuning tables.
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Spunkster
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Posts: 22737
Joined: Fri Sep 20, 2002 5:06 pm
Location: Hondata

Re: Fuel trims swinging wildly rich at 0° VTC

Post by Spunkster »

Have you discussed this with your tuner?
Ecky
Posts: 22
Joined: Sun May 26, 2019 11:35 am

Re: Fuel trims swinging wildly rich at 0° VTC

Post by Ecky »

I am the tuner.

This is a basically stock TSX motor with a 40° VTC, running the modified basemap for a K24A2.
yaggs89
Posts: 22
Joined: Tue Jan 26, 2021 9:32 pm

Re: Fuel trims swinging wildly rich at 0° VTC

Post by yaggs89 »

Glad it worked out, but why is this a problem on 0 degree only? I have similar issue...also what would the live tuning have to do with it?
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