Pretty lean across the board, IFR or VE table adjustment?
11-15-2004, 01:18 PM
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Pretty lean across the board, IFR or VE table adjustment? Quick background: high LTRIMS across the board in every MAP/rpm quadrant, some as high as 19, minimum of 7, only KR is some tip-in KR in 6th gear in the 1800-2200 RPM range.
I understand this to mean that the computer is having to add fuel to correct for a lean condititon. Question is, should I initially attempt to smooth out the LTRIMS w/ the IFR table (I do have SVO 30 injectors - and have corrected for them in the IFR, but have made no other adjustments to the IFR other than this initial correction) or should I start scaling the VE table up in the affected quadrants, or should I scale one and then the other (make big across-the-board changes w/ the IFR and follow up with VE tweaks or vice-versa)?
I have 5.3L heads, TR224 cam and the LS6 MAF (running the truck MAF table w/ no mods).
Thanks!
I understand this to mean that the computer is having to add fuel to correct for a lean condititon. Question is, should I initially attempt to smooth out the LTRIMS w/ the IFR table (I do have SVO 30 injectors - and have corrected for them in the IFR, but have made no other adjustments to the IFR other than this initial correction) or should I start scaling the VE table up in the affected quadrants, or should I scale one and then the other (make big across-the-board changes w/ the IFR and follow up with VE tweaks or vice-versa)?
I have 5.3L heads, TR224 cam and the LS6 MAF (running the truck MAF table w/ no mods).
Thanks!
11-15-2004, 01:26 PM
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The cam / heads / headers probably want your high end
VE raised and your low end VE reduced. But the VE has
nothing to do with >4000RPM, steady state conditions
(though you also will see no trimming here, only residual
trims locked in from below).
If you have high low-flow trims that get better as airflow
increases this indicates to me a VE focus; if the trims get
worse with more airflow that implicates the MAF. I think
if the MAF is clean, that truck table should have put you
right. But if there's a K&N in the picture the first thing
the MAF wants, is a bath.
VE raised and your low end VE reduced. But the VE has
nothing to do with >4000RPM, steady state conditions
(though you also will see no trimming here, only residual
trims locked in from below).
If you have high low-flow trims that get better as airflow
increases this indicates to me a VE focus; if the trims get
worse with more airflow that implicates the MAF. I think
if the MAF is clean, that truck table should have put you
right. But if there's a K&N in the picture the first thing
the MAF wants, is a bath.
11-15-2004, 03:44 PM
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Jimmyblue,
You are right... the LTRIMS go closer to their minimum value as the throttle is pushed down and airflow increases. I'll try working with the VE table a bit and see where it takes me. The MAF is new, so it shouldn't be dirty, but I'll check it nonetheless.
So - you leave the IFR table alone, right? If most of everything needs to be done in the VE table, under what circumstances (outside of what I've already adjusted for) would I want to work with the IFR table?
Thanks again for your help.
You are right... the LTRIMS go closer to their minimum value as the throttle is pushed down and airflow increases. I'll try working with the VE table a bit and see where it takes me. The MAF is new, so it shouldn't be dirty, but I'll check it nonetheless.
So - you leave the IFR table alone, right? If most of everything needs to be done in the VE table, under what circumstances (outside of what I've already adjusted for) would I want to work with the IFR table?
Thanks again for your help.
11-15-2004, 04:15 PM
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IFR represents everything to do with the fuel delivery side.
A mixture error or modification relating to the injectors,
pump, regulator, plumbing etc. belongs there.
But most engine mods aside from those specific things,
are aimed at airflow and the airflow sensors / calibrations
are the more appropriate way to re-true the system.
A mixture error or modification relating to the injectors,
pump, regulator, plumbing etc. belongs there.
But most engine mods aside from those specific things,
are aimed at airflow and the airflow sensors / calibrations
are the more appropriate way to re-true the system.
