AF Alpha Learn (LHS)

Discussions concerning the M7790 cpu

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PL
 

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Re: AF Alpha Learn (LHS)

Post by PL »

Theoretically yes!

If STFT is close to 100% then LTFT should also remain at 100% = happy days.

PL
Matt
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Re: AF Alpha Learn (LHS)

Post by Matt »

Yes it will

Final injection = TP x STFT x LTFT x fuel coefficients (fuel map + temp enrich + throttle enrich) + injector latency

As you can see any change to STFT/LTFT affects final injection pulsewidth. Seems to be +/- 28% limits
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Re: AF Alpha Learn (LHS)

Post by PL »

That's the idea!
UNISA JECS
 

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Re: AF Alpha Learn (LHS)

Post by UNISA JECS »

Hey Matt I have a concern on the B13 SR20DE are you sure that this target number isn't 128? Because on a stock B13 SR20DE by default these number start off at 128 on both STFT and LTFT
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Re: AF Alpha Learn (LHS)

Post by Matt »

It depends on ECU type. Some Nissans have 100% (64hex) and others are 128 (80hex) which shows as 128%

There is a bit flag in the ECU part number which says if it is 100 or 128 for 100%. We do read this but it appears the intepretation may not be working correctly for some models. I've seen I think it was a S13 had LTFT at 128
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Re: AF Alpha Learn (LHS)

Post by UNISA JECS »

Matt wrote:It depends on ECU type. Some Nissans have 100% (64hex) and others are 128 (80hex) which shows as 128%

There is a bit flag in the ECU part number which says if it is 100 or 128 for 100%. We do read this but it appears the intepretation may not be working correctly for some models. I've seen I think it was a S13 had LTFT at 128
Well I did some tuning on my B13's today and I learned/discovered that the target STFT is 100 and LTFT is 128, I was really able to dial this in quit quickly and nicely and while doing so I watched my O2 sensor come alive and start oscillating like it never has before at idle all the while mainting STFT @ 100 and LTFT @ 128.

Now my P11 G20 is different it wants STFT @100 and LTFT @100.
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Re: AF Alpha Learn (LHS)

Post by Matt »

I've been going through S13 SR20 code today and indeed LTFT is 0x80 when it is cleared (128% value) so it changes with some models

I'm out of time this week but will go through all models and update accordingly which ones need correction. Will change all to 0% and without the +28 offset in those difficult models
UNISA JECS
 

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Re: AF Alpha Learn (LHS)

Post by UNISA JECS »

Matt wrote:I've been going through S13 SR20 code today and indeed LTFT is 0x80 when it is cleared (128% value) so it changes with some models

I'm out of time this week but will go through all models and update accordingly which ones need correction. Will change all to 0% and without the +28 offset in those difficult models

That's cool either way once you turn the car engine off and connect Nistune it display the target trims for LTFT and STFT and then you just aim to hit the marks, I really love this feature works awesome that combined with Active Test and Clear Self Learn and its childs play.
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