deciphering LTFT and others
Thread Starter
Melting Slicks
Joined: Aug 2002
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From: Tacoma WA your Junk Yard Dogg
deciphering LTFT and others
i recently installed a predator programer and her are some of my numbers on a 70degree day at around 60mph rpms 2000 can anybody help explain what the numbers mean......short = +2.0 thru +3
long = +9.3 thru +10.0
short = -3.0 thru +1.0
long = +10.0 thru +14.0
m a p = 4.9 thanks
long = +9.3 thru +10.0
short = -3.0 thru +1.0
long = +10.0 thru +14.0
m a p = 4.9 thanks
Racer
Joined: Aug 2001
Posts: 469
Likes: 0
From: Pasadena MD
Re: deciphering LTFT and others (corvette184)
long = +9.3 thru +10.0
long = +10.0 thru +14.0
m a p = 4.9 thanks
long = +10.0 thru +14.0
m a p = 4.9 thanks
map= manifold air pressure... looks ok
[Modified by jawsski, 8:16 PM 9/8/2003]
Thread Starter
Melting Slicks
Joined: Aug 2002
Posts: 2,103
Likes: 0
From: Tacoma WA your Junk Yard Dogg
Re: deciphering LTFT and others (jawsski)
is this dangerously lean......
long = +9.3 thru +10.0
long = +10.0 thru +14.0
m a p = 4.9 thanks
You're running lean..nice to be just above 0...around +2/+3
map= manifold air pressure... looks ok
[Modified by jawsski, 8:16 PM 9/8/2003]
long = +10.0 thru +14.0
m a p = 4.9 thanks
You're running lean..nice to be just above 0...around +2/+3
map= manifold air pressure... looks ok
[Modified by jawsski, 8:16 PM 9/8/2003]
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
Re: deciphering LTFT and others (corvette184)
Don't pay attention to the STFT's
YOur LTFT's are WAY lean....you need to add more fuel... You really want your LTFT's to show -1 to -5 Which is a good range.. The reason it's better be negative is that when you go WOT (PE) mode you won't be adding the extra fuel that the LTFT's were trying to add.. As long as they are negative you just get the fuel that is in the WOT table..
I don't know how the predator programs more fuel.. But with LS1edit it is best to change the injector pulse to make it a tad richer..
YOur LTFT's are WAY lean....you need to add more fuel... You really want your LTFT's to show -1 to -5 Which is a good range.. The reason it's better be negative is that when you go WOT (PE) mode you won't be adding the extra fuel that the LTFT's were trying to add.. As long as they are negative you just get the fuel that is in the WOT table..
I don't know how the predator programs more fuel.. But with LS1edit it is best to change the injector pulse to make it a tad richer..
Racer
Joined: Aug 2001
Posts: 469
Likes: 0
From: Pasadena MD
Re: deciphering LTFT and others (chuckster)
[QUOTE]Don't pay attention to the STFT's
You really want your LTFT's to show -1 to -5 Which is a good range.. The reason it's better be negative is that when you go WOT (PE) mode ....QUOTE]
This is OK if you are going to WOT often..and I mean very often like on the track...for a daily driver the car will not have that SOTP pep at lower rpm unless you are slightly lean ..ALSO...running that rich you will get soot all over the butt end :nonod:
You really want your LTFT's to show -1 to -5 Which is a good range.. The reason it's better be negative is that when you go WOT (PE) mode ....QUOTE]
This is OK if you are going to WOT often..and I mean very often like on the track...for a daily driver the car will not have that SOTP pep at lower rpm unless you are slightly lean ..ALSO...running that rich you will get soot all over the butt end :nonod:
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Thread Starter
Melting Slicks
Joined: Aug 2002
Posts: 2,103
Likes: 0
From: Tacoma WA your Junk Yard Dogg
Re: deciphering LTFT and others (jawsski)
i just uninstalled the predator program and my numbers came back down to +1thru+5.... and i can feel the tires activate traction control again....at about 4300rpm.....i think i will avoid using the predator....i can still watch my nubers with it tho.....thanks for the help guys......ps mods are halltech t1-c,stainless works headers and a shaner t/b......i am going to the dyno monday and i will get some real numbers then hook up predator again and compare :party:
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
Re: deciphering LTFT and others (corvette184)
Dude, trust me..
You want your LTFT's negative.. Even if you don't spend a lot of time at WOT..
The LS1 performs better when the PCM is Pulling fuel (Negative) to achieve Stoich conditions.
If you have positive LTFT's when the PCM goes to WOT, that extra fuel gets added to the PE value.. this makes it difficult to tune because that value changes.
If you have negative LTFT;s when the PCM goes to WOT, the trims will LOCK out to 0 and ONLY the fuel value in the PE table will be used.
That being said, the Predator is a poor tool to make really good LTFT and PE changes. LS1edit rules... ;)
You want your LTFT's negative.. Even if you don't spend a lot of time at WOT..
The LS1 performs better when the PCM is Pulling fuel (Negative) to achieve Stoich conditions.
If you have positive LTFT's when the PCM goes to WOT, that extra fuel gets added to the PE value.. this makes it difficult to tune because that value changes.
If you have negative LTFT;s when the PCM goes to WOT, the trims will LOCK out to 0 and ONLY the fuel value in the PE table will be used.
That being said, the Predator is a poor tool to make really good LTFT and PE changes. LS1edit rules... ;)
Racer
Joined: Aug 2001
Posts: 469
Likes: 0
From: Pasadena MD
Re: deciphering LTFT and others (chuckster)
Charlie, Never mind,, I misread your thread
[/QUOTE]The LS1 performs better when the PCM is Pulling fuel (Negative) to achieve Stoich conditions.
If you have positive LTFT's when the PCM goes to WOT, that extra fuel gets added to the PE value.. this makes it difficult to tune because that value changes.
If you have negative LTFT;s when the PCM goes to WOT, the trims will LOCK out to 0 and ONLY the fuel value in the PE table will be used.
[/QUOTE]
[Modified by jawsski, 8:57 PM 9/9/2003]
[/QUOTE]The LS1 performs better when the PCM is Pulling fuel (Negative) to achieve Stoich conditions.
If you have positive LTFT's when the PCM goes to WOT, that extra fuel gets added to the PE value.. this makes it difficult to tune because that value changes.
If you have negative LTFT;s when the PCM goes to WOT, the trims will LOCK out to 0 and ONLY the fuel value in the PE table will be used.
[/QUOTE]
[Modified by jawsski, 8:57 PM 9/9/2003]
Melting Slicks
Joined: Feb 2001
Posts: 3,360
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From: DFW TX
Senior Member
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Cruise-In IV Veteran
Re: deciphering LTFT and others (chuckster)
Don't pay attention to the STFT's
So yes, the STFT's do have some relevance to understanding what is happending with the LTFT's.
Drifting
Joined: Apr 2001
Posts: 1,763
Likes: 24
From: Austin TX
Re: deciphering LTFT and others (Godspeed)
Jeremy, I use EFILive and one of the PID's that is available is a LS1 specific STFT Average. I have started watching this since it changes slower than the STFT, but faster than LTFT.
Normally when I see a positive or negative STFT Average it will eventually change the LTFT in that cell and reset the STFT Avg to zero.
Eric
Normally when I see a positive or negative STFT Average it will eventually change the LTFT in that cell and reset the STFT Avg to zero.
Eric
