When changing PE vs RPM my LTRMS change
11-24-2003, 10:20 AM
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When changing PE vs RPM my LTRMS change I'm having an issue when fine tuning my WOT. I have my LTRMS set so that they zero out at WOT. I did this by adjusting the MAF table as I have a ported MAF. At WOT my 02s are .930-.960. I logged this at the track during a 1/4 mile run with autotap. When I mult my PE vs RPM table by 96% to make it leaner what happens now is my LTRMS no longer zero out, they go positive which dumps fuel at WOT thus making it even richer like .970....What do I do now?
My mods on my 99 vette are: vararam, headers, borlas, ported maf and tb, TQ converter, I still have stock cats and gears.....
My mods on my 99 vette are: vararam, headers, borlas, ported maf and tb, TQ converter, I still have stock cats and gears.....
11-24-2003, 10:38 AM
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this is from chrisB's site:
.
In tuning part throttle we will tweak the MAF transfer function according to the l-trim values we logged. There are 2 ways of doing this, the simplest is to simply view your l-trim values/average them, and scale the entire MAF table by a percentage which will give you l-trims of -2 to -8. L-trims are in units of percent so this is easy. If our average l-trims are around +5 and we want to shoot for say, -4, then we would just multiply the entire table by 109% (or an increase of (+5 - (-4))=9 percent). Likewise if we were at -10 and wanted to shoot for negative 4 we would decrease the entire table by 6 percent, or multiply by 94%.
basically, scale your entire maf table, and moniter your LTFT's. this should solve that issue.
.
In tuning part throttle we will tweak the MAF transfer function according to the l-trim values we logged. There are 2 ways of doing this, the simplest is to simply view your l-trim values/average them, and scale the entire MAF table by a percentage which will give you l-trims of -2 to -8. L-trims are in units of percent so this is easy. If our average l-trims are around +5 and we want to shoot for say, -4, then we would just multiply the entire table by 109% (or an increase of (+5 - (-4))=9 percent). Likewise if we were at -10 and wanted to shoot for negative 4 we would decrease the entire table by 6 percent, or multiply by 94%.
basically, scale your entire maf table, and moniter your LTFT's. this should solve that issue.
11-24-2003, 10:43 AM
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Originally Posted by Vents
this is from chrisB's site:
.
In tuning part throttle we will tweak the MAF transfer function according to the l-trim values we logged. There are 2 ways of doing this, the simplest is to simply view your l-trim values/average them, and scale the entire MAF table by a percentage which will give you l-trims of -2 to -8. L-trims are in units of percent so this is easy. If our average l-trims are around +5 and we want to shoot for say, -4, then we would just multiply the entire table by 109% (or an increase of (+5 - (-4))=9 percent). Likewise if we were at -10 and wanted to shoot for negative 4 we would decrease the entire table by 6 percent, or multiply by 94%.
basically, scale your entire maf table, and moniter your LTFT's. this should solve that issue.
.
In tuning part throttle we will tweak the MAF transfer function according to the l-trim values we logged. There are 2 ways of doing this, the simplest is to simply view your l-trim values/average them, and scale the entire MAF table by a percentage which will give you l-trims of -2 to -8. L-trims are in units of percent so this is easy. If our average l-trims are around +5 and we want to shoot for say, -4, then we would just multiply the entire table by 109% (or an increase of (+5 - (-4))=9 percent). Likewise if we were at -10 and wanted to shoot for negative 4 we would decrease the entire table by 6 percent, or multiply by 94%.
basically, scale your entire maf table, and moniter your LTFT's. this should solve that issue.
11-24-2003, 11:29 AM
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FWIW there is definitely controversy regarding that - some people preferr to scale the IFR table to achieve the same ends - it really depends on what works the best for you .
Your L-Trims should not change in regards to the PE changes - you sure the changes are directly in response to this, and not just normal fluctuations?
Your L-Trims should not change in regards to the PE changes - you sure the changes are directly in response to this, and not just normal fluctuations?
11-24-2003, 11:34 AM
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Because PE affects some closed loop cells; it is a load
based forward fuel push, and the closed loop still wants
to pull back to make 14.7 in these cells, so it adjusts.
If you don't this, you will have to be more surgical in the
PE adjustment, do further adjusts to the higher-RPM,
higher-load areas and leave the midband alone. You
don't -have- to multiply the whole table, that's just the
way to start.
If the PCM was pulling out (say) 5% to compensate for
midband PE effects, and you reduced the PE some, the
LTFT would become less negative.
based forward fuel push, and the closed loop still wants
to pull back to make 14.7 in these cells, so it adjusts.
If you don't this, you will have to be more surgical in the
PE adjustment, do further adjusts to the higher-RPM,
higher-load areas and leave the midband alone. You
don't -have- to multiply the whole table, that's just the
way to start.
If the PCM was pulling out (say) 5% to compensate for
midband PE effects, and you reduced the PE some, the
LTFT would become less negative.
11-24-2003, 11:49 AM
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Originally Posted by ChrisB
FWIW there is definitely controversy regarding that - some people preferr to scale the IFR table to achieve the same ends - it really depends on what works the best for you .
Your L-Trims should not change in regards to the PE changes - you sure the changes are directly in response to this, and not just normal fluctuations?
Your L-Trims should not change in regards to the PE changes - you sure the changes are directly in response to this, and not just normal fluctuations?
11-24-2003, 11:54 AM
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Originally Posted by jimmyblue
Because PE affects some closed loop cells; it is a load
based forward fuel push, and the closed loop still wants
to pull back to make 14.7 in these cells, so it adjusts.
If you don't this, you will have to be more surgical in the
PE adjustment, do further adjusts to the higher-RPM,
higher-load areas and leave the midband alone. You
don't -have- to multiply the whole table, that's just the
way to start.
If the PCM was pulling out (say) 5% to compensate for
midband PE effects, and you reduced the PE some, the
LTFT would become less negative.
based forward fuel push, and the closed loop still wants
to pull back to make 14.7 in these cells, so it adjusts.
If you don't this, you will have to be more surgical in the
PE adjustment, do further adjusts to the higher-RPM,
higher-load areas and leave the midband alone. You
don't -have- to multiply the whole table, that's just the
way to start.
If the PCM was pulling out (say) 5% to compensate for
midband PE effects, and you reduced the PE some, the
LTFT would become less negative.
And that is exactly what happened. Because I had my LTRMS very close to "0" already when I made the WOT changes it made the LTRMS go positive. Perhaps I should just lean out say 4000 on up.
