Use STFT to modify VE
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TECH Resident
Joined: Aug 2004
Posts: 875
Likes: 2
From: Portland Oregon
Use STFT to modify VE I have been tuning with a wideband for a few years and my A/F runs mid 14's cruising. All of this tuning was with no MAF, and a few months ago the LTFT was turned off. I thought my VE was right on, now I am looking at the STFT and seeing that I am lean on the low end, and the STFT is adding fuel in quite a few cells. WOT is right on 12.7
Looking at the historygram I see that I can copy STFT and paste special into the VE table and multiply. If I copy STFT and paste to modify the VE, should I paste it 1:1, or multiply by percent 50%. This looks too easy, is this how everyone else tunes the VE?
Looking at the historygram I see that I can copy STFT and paste special into the VE table and multiply. If I copy STFT and paste to modify the VE, should I paste it 1:1, or multiply by percent 50%. This looks too easy, is this how everyone else tunes the VE?
You could, and I have, done it this way but you want
to do it with a critical eye. Every time you step into a
new airflow cell, STFTs reset and crawl back; you need
the "settled" STFT, not some transient / bogus waypoints
in the mix. Basically you have to "human filter" the data,
histogram / average numbers can contain a high garbage
content especially in street driving.
Then, too, you need to determine whether the "lean" is
real or a sensor / thermal artifact. Gauge this by whether
STFT drifts big-positive after sitting at idle, after initially
settling to a stable sane trim, following drop-to-idle.
to do it with a critical eye. Every time you step into a
new airflow cell, STFTs reset and crawl back; you need
the "settled" STFT, not some transient / bogus waypoints
in the mix. Basically you have to "human filter" the data,
histogram / average numbers can contain a high garbage
content especially in street driving.
Then, too, you need to determine whether the "lean" is
real or a sensor / thermal artifact. Gauge this by whether
STFT drifts big-positive after sitting at idle, after initially
settling to a stable sane trim, following drop-to-idle.
