Adjusting the PE table for IFR table changes, need expert help!
03-04-2004, 10:31 PM
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Adjusting the PE table for IFR table changes, need expert help! Ok, say you've multipled the whole IFR table by .93 (93%) to richen your cruising Ltrims and bring them down near 0. What would be a good place to start leaning the PE vs RPM table to compensate for the IFR table adjustments (percentage wise)? I'm thinking multiply the whole PE vs RPM table .96-.97 (leaning it by 96-97%)? Is that about right??? You do multiply the whole PE vs RPM table like with the IFR table, correct?
I don't think it's a 1:1 ratio (meaning 93% change on the IFR should not need a 93% change on the PE vs RPM), correct? I think PE vs RPM changes require less actual % of change to correspond with IFR changes, correct?
I don't have a wideband or anything, and am just going to be looking at O2s and KR for WOT, so I just want a good place to start.
Currently, I'm at .95 (95%) on the IFR table, but at cruise FTCs, I'm usually around +3 to +7 LTFT. So I want to try dropping the IFR table 2% more to .93 (93%) and see if that gets me to 0 or so. I have not yet touched the PE vs RPM table, actually I haven't even looked at it yet.
And another issue, I want to make safe changes since there will be no dyno or wideband involved in this process, so I'd rather run a little rich and lose some power than going too lean and facing knock under certain conditions (hot temps, etc.). Therefore, trying to decide if I should leave my LTFTs slightly positive just in case, or maybe just leave the PE vs RPM tables slightly rich? I know the factory O2s aren't exactly super accurate so I'd rather error on the side of a little rich at WOT.
I am really not all that interested in messing with my main VE table any further, because I have finally got it tuned perfect for warm/hot starts, though I might be able to bump my 1200rpm column by 2-5% (currently at 80% for 1200 column, might try 82 to 85%). So what effect would a slight VE change in the 1200rpm range have on low rpm LTFT? Maybe drop them a tad? Or would it even matter? And if I am going to change my VE table further, should I do that before making any more changes to the IFR or PE tables?
Actually, I'm pretty happy with how the car runs as is even with the +3 to +7 LTFT. Oddly enough, the O2 values and timing look pretty good with it like this, and the car runs strong. Idle and cruise are good as well, but I can't help but to think it could possibily be better.
Any opinions or advice is welcome. Sorry, I know it's a lot of questions in one thread but I'm thinking that all these issues need to be addressed/explained together as they all seem to effect one and other. Thanks.
I don't think it's a 1:1 ratio (meaning 93% change on the IFR should not need a 93% change on the PE vs RPM), correct? I think PE vs RPM changes require less actual % of change to correspond with IFR changes, correct?
I don't have a wideband or anything, and am just going to be looking at O2s and KR for WOT, so I just want a good place to start.
Currently, I'm at .95 (95%) on the IFR table, but at cruise FTCs, I'm usually around +3 to +7 LTFT. So I want to try dropping the IFR table 2% more to .93 (93%) and see if that gets me to 0 or so. I have not yet touched the PE vs RPM table, actually I haven't even looked at it yet.
And another issue, I want to make safe changes since there will be no dyno or wideband involved in this process, so I'd rather run a little rich and lose some power than going too lean and facing knock under certain conditions (hot temps, etc.). Therefore, trying to decide if I should leave my LTFTs slightly positive just in case, or maybe just leave the PE vs RPM tables slightly rich? I know the factory O2s aren't exactly super accurate so I'd rather error on the side of a little rich at WOT.
I am really not all that interested in messing with my main VE table any further, because I have finally got it tuned perfect for warm/hot starts, though I might be able to bump my 1200rpm column by 2-5% (currently at 80% for 1200 column, might try 82 to 85%). So what effect would a slight VE change in the 1200rpm range have on low rpm LTFT? Maybe drop them a tad? Or would it even matter? And if I am going to change my VE table further, should I do that before making any more changes to the IFR or PE tables?
Actually, I'm pretty happy with how the car runs as is even with the +3 to +7 LTFT. Oddly enough, the O2 values and timing look pretty good with it like this, and the car runs strong. Idle and cruise are good as well, but I can't help but to think it could possibily be better.
Any opinions or advice is welcome. Sorry, I know it's a lot of questions in one thread but I'm thinking that all these issues need to be addressed/explained together as they all seem to effect one and other. Thanks.
03-04-2004, 11:16 PM
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PS. I just want to confirm, when you're making a change to the PE vs RPM table to compensate for an IFR change, you do in fact highlight the entire PE vs RPM table and apply your percentage change to the whole table, correct? From all the reading I've done, this is what I gather people are doing, but I just want to confirm as I haven't actually ever touched my PE table before......
03-05-2004, 12:24 AM
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Sounds similar to how I began learning this tuning stuff... 
I'm no expert (look to NoGo et.al. for true expert advice), but I have done wayy too much reading about tuning and quite a bit of experimenting on my own vehicle. If you haven't yet, check out ls1tuning .
The typical order for tuning seems to be:
1) tune IFR for negative LTFTs at part throttle (fuel trim cells 6-14)
2) tweak VE table to tune any idle or cruise issues
3) adjust PE table to the edge of knocking, then add 1-2% fuel for safety margin (since your tuning using the knock sensors instead of a wideband)
4) bump timing up in WOT range, backing off if knock occurs, of course
5) verify AFR and fine tune with wideband
Some folks probably switch things around on that list. I'm sure experienced tuners who have tuned lots of vehicles can probably successfully adjust several or all of those things in one pass. The list I gave is really more for the DIY tuner who is learning and wants to play it safe.
Hope this is helpful. I imagine somebody else will speak up too...
good luck tuning
I'm no expert (look to NoGo et.al. for true expert advice), but I have done wayy too much reading about tuning and quite a bit of experimenting on my own vehicle. If you haven't yet, check out ls1tuning .
The typical order for tuning seems to be:
1) tune IFR for negative LTFTs at part throttle (fuel trim cells 6-14)
2) tweak VE table to tune any idle or cruise issues
3) adjust PE table to the edge of knocking, then add 1-2% fuel for safety margin (since your tuning using the knock sensors instead of a wideband)
4) bump timing up in WOT range, backing off if knock occurs, of course
5) verify AFR and fine tune with wideband
Some folks probably switch things around on that list. I'm sure experienced tuners who have tuned lots of vehicles can probably successfully adjust several or all of those things in one pass. The list I gave is really more for the DIY tuner who is learning and wants to play it safe.
Hope this is helpful. I imagine somebody else will speak up too...
good luck tuning
03-05-2004, 06:54 AM
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Originally Posted by deezel
Sounds similar to how I began learning this tuning stuff...
I'm no expert (look to NoGo et.al. for true expert advice), but I have done wayy too much reading about tuning and quite a bit of experimenting on my own vehicle. If you haven't yet, check out ls1tuning .
The typical order for tuning seems to be:
1) tune IFR for negative LTFTs at part throttle (fuel trim cells 6-14)
2) tweak VE table to tune any idle or cruise issues
3) adjust PE table to the edge of knocking, then add 1-2% fuel for safety margin (since your tuning using the knock sensors instead of a wideband)
4) bump timing up in WOT range, backing off if knock occurs, of course
5) verify AFR and fine tune with wideband
Some folks probably switch things around on that list. I'm sure experienced tuners who have tuned lots of vehicles can probably successfully adjust several or all of those things in one pass. The list I gave is really more for the DIY tuner who is learning and wants to play it safe.
Hope this is helpful. I imagine somebody else will speak up too...
good luck tuning
I'm no expert (look to NoGo et.al. for true expert advice), but I have done wayy too much reading about tuning and quite a bit of experimenting on my own vehicle. If you haven't yet, check out ls1tuning .
The typical order for tuning seems to be:
1) tune IFR for negative LTFTs at part throttle (fuel trim cells 6-14)
2) tweak VE table to tune any idle or cruise issues
3) adjust PE table to the edge of knocking, then add 1-2% fuel for safety margin (since your tuning using the knock sensors instead of a wideband)
4) bump timing up in WOT range, backing off if knock occurs, of course
5) verify AFR and fine tune with wideband
Some folks probably switch things around on that list. I'm sure experienced tuners who have tuned lots of vehicles can probably successfully adjust several or all of those things in one pass. The list I gave is really more for the DIY tuner who is learning and wants to play it safe.
Hope this is helpful. I imagine somebody else will speak up too...
good luck tuning
LS1tuning is a great site, and I've read a lot over there. If I don't get the answers I need here then I'm gonna post it over there......
I drive the car three seasons of the year, with a variance in temp of as much as 50-60 deg., and I run my engine temps in the 194-210* range, so I'd rather stay on the rich side and not tune for the "edge of KR" so to speak. I'm not worried about leaving a couple HP on the table (I know I'll never get it perfect without a wideband), I just want to get "close" to peak potential.
I guess my big worry about adjusting the LTFTs too far with the IFR table is what effect it'll have on my VE table adjustments? And the reverse, what effect any further changes to the VE table would have on LTFT? I was finally able to dial in my warm starts perfect and I don't want to mess that up....
I guess I'm still left with the question of, what should be my "safe" ratio of PE adjustments to compensate for IFR adjustments? I'm thinking that my IFR table will likely be at 90% to 93% to get the LTFT in line, so would say a 96-97% PE adjustment be a good "safe" place?
PS. My MAF is 100% stock down to the screen. I have not touched the MAF tables at all and don't really plan to as the MAF is stock....
Thanks again for whatever help you guys can give.....
Last edited by RPM WS6; 03-05-2004 at 07:05 AM.
03-05-2004, 07:17 PM
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Ok, so how about I try this, keep in mind that my LTFTs are about +5 on average:
Take the IFR table down another 3% (already took it down 5% to get the LTFT where they are now). IFR table will now be at a total of .92 x stock (92%).
PE vs RPM table (whole table) multiply by .96 (96%) to offset the IFR changes (keep in mind I have never touched the PE vs RPM table before so this adjustment will be compensating for the full 8% change on the IFR table).
So basically what I'll be doing is a 2:1 ratio on percentage changes to IFR vs the PE table just to be safe (no wideband). For each 2% richer I run the IFR table, I'll be running the PE table 1% leaner, for a total of stock X .92 (92%) on the IFR and stock X .96 (96%) on the PE.
How's that sound? Or should I maybe do 94% on the PE for a 92% on the IFR???? Or can I do a 1:1 deal pushing both the IFR and PE to 92% and still be safe (no KR and such)????
Help! 
Take the IFR table down another 3% (already took it down 5% to get the LTFT where they are now). IFR table will now be at a total of .92 x stock (92%).
PE vs RPM table (whole table) multiply by .96 (96%) to offset the IFR changes (keep in mind I have never touched the PE vs RPM table before so this adjustment will be compensating for the full 8% change on the IFR table).
So basically what I'll be doing is a 2:1 ratio on percentage changes to IFR vs the PE table just to be safe (no wideband). For each 2% richer I run the IFR table, I'll be running the PE table 1% leaner, for a total of stock X .92 (92%) on the IFR and stock X .96 (96%) on the PE.
How's that sound? Or should I maybe do 94% on the PE for a 92% on the IFR???? Or can I do a 1:1 deal pushing both the IFR and PE to 92% and still be safe (no KR and such)????
Help!
03-06-2004, 09:09 AM
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If you're happy with part throttle transitions and "feel" then I'd say you're done with the VE table for now. At first, I tried to tune my IFR to get LTFTs right at 0. This was tricky because they drift around. So I ended up going about 2% lower on the IFR to keep the LTFTs at or below 0 all the time. LTFTs from 0 to -5 in cells 6-14 should be good. Mine tend to sit at -2.xx to -4.xx.
If you think the O2s and timing look good, and are getting zero knock, then just start leaning out the PE table 1 or 2% at a time until you do get knock. Then give it 1 or 2% back in the PE table to be on the safe side.
If you think the O2s and timing look good, and are getting zero knock, then just start leaning out the PE table 1 or 2% at a time until you do get knock. Then give it 1 or 2% back in the PE table to be on the safe side.
03-06-2004, 09:26 AM
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Originally Posted by deezel
If you think the O2s and timing look good, and are getting zero knock, then just start leaning out the PE table 1 or 2% at a time until you do get knock. Then give it 1 or 2% back in the PE table to be on the safe side.
My concern is, the O2s look decent now with the IFR table at 95% of stock and the LTFTs averaging +5% (stock PE table for now), so if I'm going to drop the IFR table another 3-5% or so (90-92%), this will cause the car to go richer at WOT as it will think the injectors are smaller, correct? So even though I've gotten rid of the extra +5% fuel being added to WOT by the LTFTs, I'm still going to be overly rich at WOT considering the 8% change of the IFR table with only a 1-2% change in the PE, correct?
So this is why I think, for an overall change in my IFR table of say 92% of stock, that I should start the PE table at 96% of stock. Does this sound about right? I think doing 98 or 99% on the PE table would be a waste of time if I've already gone 92% on the IFR table, correct?
I just hate to beat the car (WOT logs) for no reason, and I really think that a 1-2% PE change is way too small to compensate for a 8% IFR chage. What do you think?
Thanks again for the replies.
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03-06-2004, 09:38 AM
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I have seen some guys post that they did a 1 to 1 change - lower IFR 5% and lower PE 5% also. They seemed to think it got them pretty close to where they wanted to be. So, I don't think its unreasonable to try that.
03-06-2004, 09:54 AM
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Originally Posted by deezel
I have seen some guys post that they did a 1 to 1 change - lower IFR 5% and lower PE 5% also. They seemed to think it got them pretty close to where they wanted to be. So, I don't think its unreasonable to try that.
Looking at my LTFT averaging +5, I think I will probably try going 5% lower on the IFR tables (total of 90% of stock), and start at 95% of stock on the PE table.
While a 1:1 change might have worked for some, since I've only got the O2s and the KR readings to work with and I run my motor a little hotter than most (as high as 210*) I'm gonna try 2:1 to start with. If 95% still has me way too rich at WOT, I'll do 93% and see how that works.
Thanks again for your help.
PS. When I do the PE vs RPM table changes, I do multiply the whole table by whatever percentage I decide to use, correct? I'm not just picking certain rpms for this, but all of them on the PE, correct? Just want to be sure as I haven't even looked at that table yet. Thanks.
