LS1TECH - Camaro and Firebird Forum Discussion

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-   -   Negative LTFT's (I have searched) (https://ls1tech.com/forums/pcm-diagnostics-tuning/409631-negative-ltfts-i-have-searched.html)

Wilds Nov 14, 2005 11:08 PM

Negative LTFT's (I have searched)
 
I was wondering if someone can tell me why my LTFT's and STFT's would both be in the negatives at idle. If I unplug my O2's then they are all around 0 and the LTFT's jump around from +10-12 to -5,-10 and the STFT's stay around 0. When the O2's are plugged in and you give it gas then the LTFT's go way down around -13,-18 and the STFT's dip to around -3,-8. Any insight as to what's going on or is that about normal? I was also wondering what the MAP should be reading at idle. When I'm watching this on my Predator the MAP is around 3 or 4 psi at idle and get has high as 13-18 psi while driving. I have checked for vacuum leaks and haven't found any as of yet. I didn't know if the LT,STFT's have something to do with that or not. Can anyone tell me about what the O2's should be reading at idle? I was also wondering if anyone can tell me what the code Nd0650 might have to do with. Thanks a lot.

Chris

CAT3 Nov 15, 2005 01:48 AM

There is a lot of your questions and answers in the stickies on tuning, the how to is a good one.
Anyway, O2 are going to jump around unless your WOT, at least they should. At WOT they will stabilize, something like 880 or 920 etc.
LTFTs are a little more negative than I prefer, but as long as they are negative your still good. The more time you drive, the closer they will be to the STFT's.

SSpdDmon Nov 15, 2005 11:14 AM

Negative LTFT's mean you're running rich. Unplugging the O2's puts you into open-loop and the computer has no way of knowing/correcting your AFR. If the STFT's don't stay within +/-3, it means one of two things. Either your LTFT's haven't been learned yet or your tune is un-even throughout the different driving conditions you are seeing. Unless you're near someone (like RWTD) who can tune your car on a finite level through some software that works with the Predator, I'd highly suggest putting your car back to stock, selling the hand-held and picking up a copy of EFI Live, HP Tuners, etc.

Wilds Nov 15, 2005 12:58 PM

OK, thanks a lot guys. I'm headed home to drive it a bit more and we'll see what happens. I plan on getting a copy of EFI Live soon. It's hard to put my truck back to stock seeing has how I just spent the summer droppin that LS1 into my S-10 4x4! :devil:


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