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View Full Version : lean LTFTs, logs attached (NB "tuning")



Boost
October 2nd, 2010, 11:22 AM
I am trying to figure out why my LTFTs are consistently positive (lean). There are some variables / possibilities, and I am simply looking to learn.

DISCLAIMER: I am aware that I need to install fresh oxygen sensors, get a WB and dial in AFRs, then adjust timing. I know that I am not tuning anything, simply experimenting blindly with theories and ideas. Sorry. (hey lots of manufacturers so the same :hihi:)

I am wondering whether the aged stock narrow band sensors, possible exhaust leaks, or the fact that I need to tune the MAF are causing my positive LTFTs. I have previously run an experimental blind tune that was nice considering even higher LTFTs, some KR, and too much timing. As I am working back towards (blind) sanity - reduced timing and bumped VE (don't laugh :angel_innocent:) KR is eliminated and LTFT is 0.0 under load but there isn't much torque and still overall positive LTFT.

Maybe it's just the low speed / load areas that are causing it?? Also note the insanely high IATs are correct and while they don't seem to be causing ping as expected, I am sure they are robbing big power.

Again, I am simply learning what moves what in which direction. Yes, there are better ways even to learn. But I have a journal with a complilation of all your intellingent responses to base my experiments on :fluffy: (seriously) so please don't hesitate to point anything out if you have time to look, THANKS!!!

WeathermanShawn
October 2nd, 2010, 01:58 PM
Boost, those LTFT's are not that bad.

With your MAF Enabled, you will find almost a 1:1 ratio with LTFT's and MAF Airflow. You could do an entire MAF Calibration (CALC. VE Table) or you could do a +5% LTFT Average to your entire MAF curve.

That is definitely a little more of a 'hack' that way, but with LTFT's at or below +5%..it will work!