LTFT +5 & +6 bad?
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LTFT +5 & +6 bad? I checked my LTFT's today and from cells 4-16 I am getting +5 and +6 LTFTs. My mods are below. Is this ok for now?
I am going to be installing MAC headers with carsound cats soon, so I am trying to get a baseline reading before I make any changes.
Thanks!
Tommy <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
I am going to be installing MAC headers with carsound cats soon, so I am trying to get a baseline reading before I make any changes.
Thanks!
Tommy <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Re: LTFT +5 & +6 bad? could be worse...
I believe I read somewhere on here the stock cars LTRIMS come from the factory with like 0 to +4 or so readings?? Maybe I read it wrong though...
also i think headers usually richen the car so they should drop some after headers... again i could be wrong <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
I believe I read somewhere on here the stock cars LTRIMS come from the factory with like 0 to +4 or so readings?? Maybe I read it wrong though...
also i think headers usually richen the car so they should drop some after headers... again i could be wrong <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
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Re: LTFT +5 & +6 bad? So... the $10,000 question is:
Should installing Mac headers cause the ltrims to go more toward the negative side, or just go higher on the positive side?
Thanks.
Tommy <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Should installing Mac headers cause the ltrims to go more toward the negative side, or just go higher on the positive side?
Thanks.
Tommy <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Re: LTFT +5 & +6 bad? The limits for LTFT are -23% to +23% before the DTC goes set, but the STFT has to ALSO be at its' limit in the same direction either rich or lean as the associated LTFT for the DTC to go set. STFT limits are -5% to +5% to make the DTC go set. The ideal value is 0% of course for both LTFT and STFT, but this in NOT the ideal world. It's like playing the "Price is Right" with a twist. The right price is 0%, but you can't go over OR under to achieve the ideal. There is no penalty if you don't achieve the ideal UNLESS you excede the LIMITS which is your MIL comes "ON".
Staging Lane
Joined: Feb 2002
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From: Newport, Michigan
Re: LTFT +5 & +6 bad? TaTommy: If you make another mod like headers, then it makes little difference where you are now on LTFTs. You must have a scanner device, so make your next mod and report back to this board what you found.
It would be interesting to know what the addition of headers does to your LTFTs by themselves.
It is my understanding that factory stock cars will run +4% to +6% on LTFTs, FWIW.
It would be interesting to know what the addition of headers does to your LTFTs by themselves.
It is my understanding that factory stock cars will run +4% to +6% on LTFTs, FWIW.
Re: LTFT +5 & +6 bad? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Doc99SShome:
<strong> It is my understanding that factory stock cars will run +4% to +6% on LTFTs, FWIW. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">i knew I heard that before <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
<strong> It is my understanding that factory stock cars will run +4% to +6% on LTFTs, FWIW. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">i knew I heard that before <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
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Re: LTFT +5 & +6 bad? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by The Dragon:
<strong> Actually our cars come rich from the factory <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Try and get your Lterms -1. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">ahh gotcha... i swore I saw something about them having slightly positive LTRIMS though..
but either way it is ideal to have them in the -4 or -3 range...
<strong> Actually our cars come rich from the factory <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Try and get your Lterms -1. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">ahh gotcha... i swore I saw something about them having slightly positive LTRIMS though..
but either way it is ideal to have them in the -4 or -3 range...
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Re: LTFT +5 & +6 bad? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 98TAauto:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Doc99SShome:
<strong> It is my understanding that factory stock cars will run +4% to +6% on LTFTs, FWIW. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">i knew I heard that before <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I get negative integers on the Collector. Got similar results on her previous car, a '01 WS6.
FWIW
I don't know . . . maybe the fact that I did both taps when each car had very little break-in miles affected the readings <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
<small>[ February 03, 2003, 05:11 PM: Message edited by: The Dragon ]</small>
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Doc99SShome:
<strong> It is my understanding that factory stock cars will run +4% to +6% on LTFTs, FWIW. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">i knew I heard that before <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I get negative integers on the Collector. Got similar results on her previous car, a '01 WS6.
FWIW
I don't know . . . maybe the fact that I did both taps when each car had very little break-in miles affected the readings <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
<small>[ February 03, 2003, 05:11 PM: Message edited by: The Dragon ]</small>
Re: LTFT +5 & +6 bad? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by roadrunner-r:
<strong> My qestion is if iam at plus LTS+5-8 iam rich or lean? Or what if there -5-8? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Technically, you are not rich or lean. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> The PCM is compensating, and its compensation is to shoot just a tad more fuel in than theorhetically calculated. So the engine is not running lean, the PCM is keeping it at stoich by 'learning'. However, the *trend* on a (+) LTRIM is that you are starting to run towards lean, but the PCM is compensating. If you start railing out the trims (like at +23 where it won't go any higher), THEN you are lean. But if you're within the 'moving' area of the trims, the PCM keeps you OK.
Remember, trims are a *compensating* factor. If your trims are moving around, that is *fine*. I personally like to see them slightly negative (PCM pulling fuel out slightly - aka PCM thinks it's running slightly rich). That's just my personal preference, based on my LT1 experiences. A few points on either side is nothing to make a fuss about. But if you see it getting out one way or the other (I'd say outside of +/- 10-15% or higher), you need to do some work.
-Andrew
<strong> My qestion is if iam at plus LTS+5-8 iam rich or lean? Or what if there -5-8? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Technically, you are not rich or lean. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> The PCM is compensating, and its compensation is to shoot just a tad more fuel in than theorhetically calculated. So the engine is not running lean, the PCM is keeping it at stoich by 'learning'. However, the *trend* on a (+) LTRIM is that you are starting to run towards lean, but the PCM is compensating. If you start railing out the trims (like at +23 where it won't go any higher), THEN you are lean. But if you're within the 'moving' area of the trims, the PCM keeps you OK.
Remember, trims are a *compensating* factor. If your trims are moving around, that is *fine*. I personally like to see them slightly negative (PCM pulling fuel out slightly - aka PCM thinks it's running slightly rich). That's just my personal preference, based on my LT1 experiences. A few points on either side is nothing to make a fuss about. But if you see it getting out one way or the other (I'd say outside of +/- 10-15% or higher), you need to do some work.
-Andrew
Re: LTFT +5 & +6 bad? Pos + means ADDIND fuel. Neg - means SUBTRACTING fuel. The PCM does this by increasing OR decreasing the pulsewidth of the signal to turn your injectors on. Both LTFT and STFT jump around while your driving. STFT is going to be much more active than LTFT because LTFT is the RANGE you fuel management is in. The STFT is the small changes that are made to pulsewidth WITHIN that LTFT range. If your STFTs get to the limit on one side of the LTFT range or the other the range MOVES to get the STFT back in the center of the range again. It keeps doing this until it can't move any more without reaching the limits which is when the DTC MIL comes "ON". You can't make LTFTs and STFTs go where you want them to go UNLESS you do it thru software like LS1Edit which means you FOOLING the PCM into believing that a condition exists that is NOT present in you engine.
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Re: LTFT +5 & +6 bad? I think I understand the whole "PCM compensating" thing, but I also thought the LTFTs have some influence on WOT.
EX.
if PCM is adding fuel during regular throttle (+LTRMs) then it will add a little more during WOT (causing it to be richer)
if PCM is subtracting fuel during regular throttle (-LTRMs) then is will take a little away during WOT (causing it to be leaner)
Thanks for all the insights!
Tommy <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
EX.
if PCM is adding fuel during regular throttle (+LTRMs) then it will add a little more during WOT (causing it to be richer)
if PCM is subtracting fuel during regular throttle (-LTRMs) then is will take a little away during WOT (causing it to be leaner)
Thanks for all the insights!
Tommy <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Re: LTFT +5 & +6 bad? It only works one way.
If the LTerms are positive they get factored in to the WOT fueling, adding fuel, causing the car to run richer than your tune.
If the Lterms are negative they will be dismissed when the car goes WOT.
Just to give you an idea. LTerms of ~6 will drop the a/f from ~13.0 to ~12.4
Good Luck,
Kevin
If the LTerms are positive they get factored in to the WOT fueling, adding fuel, causing the car to run richer than your tune.
If the Lterms are negative they will be dismissed when the car goes WOT.
Just to give you an idea. LTerms of ~6 will drop the a/f from ~13.0 to ~12.4
Good Luck,
Kevin
