LTERMS ?
Thread Starter
Staging Lane
Joined: Jan 2002
Posts: 53
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LTERMS ? I'm trying to get my LTERMS down to zero using a MAFT and keep seeing a discrepency between one bank and another of about 4-10 %. Is this normal or is one of my 02's dead.
Thanks.
<img border="0" alt="[Chevrolet]" title="" src="graemlins/camaro.gif" />
Thanks.
<img border="0" alt="[Chevrolet]" title="" src="graemlins/camaro.gif" />
Re: LTERMS ? LTERMS? I hope you didn't get that word from one of my posts... We use that term at work quite a bit and I could have easily got mixed up. The correct term would be LTRIMS (for Long-term fuel TRIM). Anyway, It's normal for the two banks to be out of balance but I'd say a 10% difference is abnormal. I usually see a 2-5% difference.
Teching In
Joined: Feb 2002
Posts: 44
Likes: 0
From: Willow Springs, IL
Re: LTERMS ? You may also be fighting a losing battle by trying to do this with a MAFT.
It is only a device to fool the fuel tables long enough so that you see results and then the PCM will relearn fuel trims based on the existing fuel tables in the program.
What you can do to get around this is to change your MAFT to get the desired LTRIMS and then disconnect your battery every 3-5 startings and you should see fairly consistant results. Otherwise, the PCM will just relearn the LTRIMS and you'll be off again.
I hope that wasn't too confusing. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
It is only a device to fool the fuel tables long enough so that you see results and then the PCM will relearn fuel trims based on the existing fuel tables in the program.
What you can do to get around this is to change your MAFT to get the desired LTRIMS and then disconnect your battery every 3-5 startings and you should see fairly consistant results. Otherwise, the PCM will just relearn the LTRIMS and you'll be off again.
I hope that wasn't too confusing. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
Teching In
Joined: Feb 2002
Posts: 16
Likes: 0
From: Arizona
Re: LTERMS ? BV,
Im not sure I buy your argument with the MAFT.
Its only a device that adds an offset to a normal PCM input, e.g., MAF. So how is an offset, "fooling the PCM"? That statement assumes that the MAFT offset is outside some lookup table value and after so many cycles utilizing a value outside the expected range, then the PCM opts to another algorithm and what? ignores the MAF offset (MAFT) or ingores the MAF input completely?
Just trying to figure out why you think the MAFT is worthless. Then again, Im using one and have always thought that the inconsistancies in my Atap data were not the MAFT but the data collection device.
Tks
Rick 99FRC heads,cam,Z06 intake, UD pulley, Headers, tuning with maft and hpp3, soon to be tuned with ls1edit.
Im not sure I buy your argument with the MAFT.
Its only a device that adds an offset to a normal PCM input, e.g., MAF. So how is an offset, "fooling the PCM"? That statement assumes that the MAFT offset is outside some lookup table value and after so many cycles utilizing a value outside the expected range, then the PCM opts to another algorithm and what? ignores the MAF offset (MAFT) or ingores the MAF input completely?
Just trying to figure out why you think the MAFT is worthless. Then again, Im using one and have always thought that the inconsistancies in my Atap data were not the MAFT but the data collection device.
Tks
Rick 99FRC heads,cam,Z06 intake, UD pulley, Headers, tuning with maft and hpp3, soon to be tuned with ls1edit.
TECH Resident
Joined: Jan 2002
Posts: 754
Likes: 0
From: USA
Re: LTERMS ? The PCM does not relearn back to where it was before the MAFT.
The PCM is still getting a constant live valid signal, its just higher or lower freq depending on the MAFT setting, thus the PCM acts the same as without the MAFT.
What seems like relearn is people making MAFT changes, doing a PCM scan before proper engine run time and then later do a scan and see the LTFT is not the same and assume PCM is learning around the MAFT signal. Also weather temp changes would require a fine tune of MAFT to maintain a zero LTFT value.
I had a MAFT in for 1 year and it never went back to the LTFT values it had before the maft and I also have helped at least 40 other C5 owners and monitor their PCMs all the time and their's also have not reverted back.
The PCM is still getting a constant live valid signal, its just higher or lower freq depending on the MAFT setting, thus the PCM acts the same as without the MAFT.
What seems like relearn is people making MAFT changes, doing a PCM scan before proper engine run time and then later do a scan and see the LTFT is not the same and assume PCM is learning around the MAFT signal. Also weather temp changes would require a fine tune of MAFT to maintain a zero LTFT value.
I had a MAFT in for 1 year and it never went back to the LTFT values it had before the maft and I also have helped at least 40 other C5 owners and monitor their PCMs all the time and their's also have not reverted back.
Re: LTERMS ? I noticed after extensive tuning with the MAFT.That it took alot of timimg out at WOT.
With MAFT-L-trims around -2 - +2 Timing would top out at 23deg.
Stock tuning (no MAFT) and 100 mile learn time L-trims would be +5% and timing is at 28deg.
Needless to say,I tossed the MAFT because without it gave a much better seat of the pants feeling.
Dynoing Saturday to compare.
With MAFT-L-trims around -2 - +2 Timing would top out at 23deg.
Stock tuning (no MAFT) and 100 mile learn time L-trims would be +5% and timing is at 28deg.
Needless to say,I tossed the MAFT because without it gave a much better seat of the pants feeling.
Dynoing Saturday to compare.
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Verdad Gallardo Re: LTERMS ? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Nic00Z28M6:
<strong>Thats why I tune my Ltrims to be around +7 to +10 because my timing seems to be best around there.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I learned that the long way <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
<strong>Thats why I tune my Ltrims to be around +7 to +10 because my timing seems to be best around there.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I learned that the long way <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />