Negative LTFT's (I have searched)
Thread Starter
Staging Lane
Joined: May 2005
Posts: 66
Likes: 0
From: Indianapolis, IN
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
Chris
Last edited by Wilds; Nov 14, 2005 at 11:23 PM.
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.
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.
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.
Thread Starter
Staging Lane
Joined: May 2005
Posts: 66
Likes: 0
From: Indianapolis, IN
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! 
