LTFT's positive, STFT's negative???

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May 1, 2005 | 07:05 PM

My90Iroc

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LTFT's positive, STFT's negative???

I'm trying to learn tuning with HP Tuners and I've been logging and tweaking a little bit. I began by just logging everything that was going on to get a baseline data log. Next I disconnected and turned off the MAF and logged the STFT's. Logging STFT's and looking at the histogram (set on average) showed negative. I made changes according to this, plugged everything back in, logged again and my LTFT's were worse than when I started.

I noticed that my LTFT's are positive but when I logged STFT's they were negative. Why are these opposite if they're both demonstrating how the computer is compensating for the tune? Shouldn't they both be on the same side of zero?

May 4, 2005 | 05:43 AM

My90Iroc

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BTW I have both histograms (LTFT and STFT) set to average for the playbacks.

Can someone explain why LTFT's show high positive numbers and STFT's show high negative numbers?

May 4, 2005 | 08:33 AM

txhorns281

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You LTFTs learn to bring your STFTs to zero. Ideally, we want both of these to be as close to zero as possible. Your MAF is the culprit of your ill effects.

May 4, 2005 | 06:35 PM

My90Iroc

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Quote:

Originally Posted by txhorns281

You LTFTs learn to bring your STFTs to zero. Ideally, we want both of these to be as close to zero as possible. Your MAF is the culprit of your ill effects.

I made changes after logging the STFT's with the MAF disconnected. The STFT's that I logged were negative and I cut the values in half then added them to my VE table. I then hooked the MAF back up and let the LTFT's relearn themselves to see the effects of my changes. My changes actually moved the LTFT's farther from zero rather than closer, so this is where my confusion lies.

Did I do anything wrong here?

May 5, 2005 | 09:28 AM

txhorns281

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Quote:

Originally Posted by My90Iroc

In SD (Mafless) some people tune with their STFTs, but this is after their LTFTs are very very very close. I personally never did, I used a wideband and tuned, but essentially I was aligning my LTFTs. If you do not have a wideband then you want to pull your MAF off, tune with your LTFTs, get them close, and when you plug your MAF back in, expect your trims to be off again, you can either do some MAF scaling to bring your trims back inline, or do a full MAF recalibration which will be more accurate.

May 6, 2005 | 09:10 AM

soundengineer

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Quote:

Originally Posted by txhorns281

You LTFTs learn to bring your STFTs to zero. Ideally, we want both of these to be as close to zero as possible. Your MAF is the culprit of your ill effects.

I thought your STFT's teach your LTFT's to get them closer to zero ???

I tuned with STFT's only...
and my LTFT's are always at 0/-2... my stft's are within 0/-4... all the time!!

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