LS1TECH - Camaro and Firebird Forum Discussion

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-   -   How EXACTLY are LTFT's calculated? (https://ls1tech.com/forums/pcm-diagnostics-tuning/108194-how-exactly-ltfts-calculated.html)

sbrown99TA Oct 18, 2003 08:46 PM
How EXACTLY are LTFT's calculated?
 
Does anybody know exactly how the LTFT's are calculated? I have been helping a few friends (and they helping me too, thanks Mark :) ) and this just seems to keep us all kind of confused. We've come to the conclusion that the finer points of PCM tuning are about tricking the PCM, but it would be a lot easier to trick it if we knew what it was looking for.

I know how to do all the stuff...IFR tables, MAF tables, blah blah, but how does the PCM calculate it? When watching my friends Z06 on the dyno with a wideband, the computer puts the AFR at 14.7 too damn quick to just be reading the 02's (I think). Any thoughts or input would be appreciated. Thanks.

Bink Oct 18, 2003 10:20 PM
Re: How EXACTLY are LTFT's calculated?
 
Does anybody know exactly how the LTFT's are calculated? I have been helping a few friends (and they helping me too, thanks Mark :) ) and this just seems to keep us all kind of confused. We've come to the conclusion that the finer points of PCM tuning are about tricking the PCM, but it would be a lot easier to trick it if we knew what it was looking for.

I know how to do all the stuff...IFR tables, MAF tables, blah blah, but how does the PCM calculate it? When watching my friends Z06 on the dyno with a wideband, the computer puts the AFR at 14.7 too damn quick to just be reading the 02's (I think). Any thoughts or input would be appreciated. Thanks.
PCM uses the O2 sensor input and adjusts via the Injector Base PulseWidth (IBPW) equation. We don't know what the Inj.Base PW Equation is ( well, I don't). The VE table is used to modify (factor) the IBPW equation. Here's an excellent explanation of LTFT cells and VE. VE Thread Hope this helps some.
joel


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