New to LS1 Edit and have LTFT ?'s, I searched for hours.
09-21-2003, 04:33 PM
#1
Launching!
Thread Starter
Join Date: Sep 2003
Posts: 240
Likes: 0
Received 0 Likes
on
0 Posts
New to LS1 Edit and have LTFT ?'s, I searched for hours. Me and my friend that has a 2001 Corvette went in together and bought LS1 Edit and EFI Live. I'm kind of new to it, but not retarded. I'm just confused. I know that to get my LTFT's in check, which read in the +20 range, I need to scale my MAF table (ported), and then play with the IFR table. But that just does not make sense to me.
Here is why. My friends cam is a custom 230/232, his LTFT's are about where mine are. His MAF is descreened, so I scaled the table by about 3% up, which helped the smell of fuel at idle go away and the car ran a little better at part throttle. But, the LTFT's did not move (well, shortly, but went back to where they were). So, no big deal, I need to play with the IFR table. This is where I don't understand what you guys are doing.
It seems to me that adjusting to get the LTFT's in the 0/-1.0 range by adjusting the IFR, you are really just dumping more fuel to trick the 02's into thinking the car is not running lean, when in reality it is not running lean. I think, from what I know, that the 02's may get a lot of false readings at idle and part throttle on cars that have cams with a lot of overlap because of the dirty air/fuel mixture, which does not completely burn and some of the intake charge gets sucked right out to the exhaust, which the 02's see as the engine running lean because of the clean air. Right?
The only way that makes sense to me to really get it right is through the VE table, right?
Oh, and I tried the IFR table to fix it just to see and his car felt VERY sluggish at part throttle, which to me meant that it was getting too much fuel, but the LTFT's looked much better. My car did not bog as bad as his did when we adjusted it (tried 99.5%, 99%, 98.5%, etc., down to 96%) and it either did nothing to help the LTFT's or made the car bog.
Sorry for the long post, I read every post made for like the last 5 months last night (about 7 hours if you feel like trying it, just FYI), and didn't really find anything to help me. Thanks in advance.
My mods are in the sig if you need to know them.
Here is why. My friends cam is a custom 230/232, his LTFT's are about where mine are. His MAF is descreened, so I scaled the table by about 3% up, which helped the smell of fuel at idle go away and the car ran a little better at part throttle. But, the LTFT's did not move (well, shortly, but went back to where they were). So, no big deal, I need to play with the IFR table. This is where I don't understand what you guys are doing.
It seems to me that adjusting to get the LTFT's in the 0/-1.0 range by adjusting the IFR, you are really just dumping more fuel to trick the 02's into thinking the car is not running lean, when in reality it is not running lean. I think, from what I know, that the 02's may get a lot of false readings at idle and part throttle on cars that have cams with a lot of overlap because of the dirty air/fuel mixture, which does not completely burn and some of the intake charge gets sucked right out to the exhaust, which the 02's see as the engine running lean because of the clean air. Right?
The only way that makes sense to me to really get it right is through the VE table, right?
Oh, and I tried the IFR table to fix it just to see and his car felt VERY sluggish at part throttle, which to me meant that it was getting too much fuel, but the LTFT's looked much better. My car did not bog as bad as his did when we adjusted it (tried 99.5%, 99%, 98.5%, etc., down to 96%) and it either did nothing to help the LTFT's or made the car bog.
Sorry for the long post, I read every post made for like the last 5 months last night (about 7 hours if you feel like trying it, just FYI), and didn't really find anything to help me. Thanks in advance.
My mods are in the sig if you need to know them.
09-21-2003, 04:53 PM
#2
FormerVendor
iTrader: (1)
Join Date: Feb 2002
Location: Waldorf, MD
Posts: 3,059
Likes: 0
Received 0 Likes
on
0 Posts
Re: New to LS1 Edit and have LTFT ?'s, I searched for hours. Is your maf de-screened ported or stock. If it is stock revert back to the stock MAF table and tune for the LTFT's via IFR and for smaller more minute adjustments tune using the VE table. There is a forumla for figuring out VE while the car is running maybe you should use this formula
to see if it corresponds with your VE table in edit. LTFT's are the computers way of keeping the car running at a target A/F ratio. If the program (stock) cant meet the requirements the computer adjust accordingly. This causes problems during WOT runs because the computer then dumps fuel indiscrimantly to acheive the target A/F ratio. sometiems it isnt enough and causes high rpm pinging (KR). also when adjusting your "tune" be sure and turn COT (catylitc Over temp protection) off. This is also the computers way of dumping uneccesary fuel into the mix anbd preventing a lean condition which may be desirable in some cases. So as much as you tune the computer will disagree with you and add more fuel causing you to rack your brain about the changes you have made
here is the thread with VE?IFR tuning and the formulas associated with it
https://ls1tech.com/threads/showflat...=7&fpart=1
to see if it corresponds with your VE table in edit. LTFT's are the computers way of keeping the car running at a target A/F ratio. If the program (stock) cant meet the requirements the computer adjust accordingly. This causes problems during WOT runs because the computer then dumps fuel indiscrimantly to acheive the target A/F ratio. sometiems it isnt enough and causes high rpm pinging (KR). also when adjusting your "tune" be sure and turn COT (catylitc Over temp protection) off. This is also the computers way of dumping uneccesary fuel into the mix anbd preventing a lean condition which may be desirable in some cases. So as much as you tune the computer will disagree with you and add more fuel causing you to rack your brain about the changes you have made
here is the thread with VE?IFR tuning and the formulas associated with it
https://ls1tech.com/threads/showflat...=7&fpart=1
09-21-2003, 05:01 PM
#3
Launching!
Thread Starter
Join Date: Sep 2003
Posts: 240
Likes: 0
Received 0 Likes
on
0 Posts
Re: New to LS1 Edit and have LTFT ?'s, I searched for hours. I did, I put the stock MAF on, and know how to get the LTFT's close, but I just don't understand why are we supposed to use the IFR table? Why do the 02's think they need more fuel at idle and part throttle in a car with a cam?
Also, forgot to mention this, on his (the '01 Vette), we multiplied the IFR by 99.5%, which helped a little on the LTFT's, but anything more than 99% the car bogs really bad on take off. I brought the VE table down 15% from 400-1200 rpm too, all the MAP readings. It bogs BAD, like undriveable. So on his car, I can't scale the IFR table any more and not have the car bog, but the LTFT's are still way off. This makes sense to me, because the car does not actually need more fuel, it just thinks it does, right?
Also, forgot to mention this, on his (the '01 Vette), we multiplied the IFR by 99.5%, which helped a little on the LTFT's, but anything more than 99% the car bogs really bad on take off. I brought the VE table down 15% from 400-1200 rpm too, all the MAP readings. It bogs BAD, like undriveable. So on his car, I can't scale the IFR table any more and not have the car bog, but the LTFT's are still way off. This makes sense to me, because the car does not actually need more fuel, it just thinks it does, right?
