First off, thanks for all replies!!
Originally Posted By: Trav
Try cleaning the MAF sensor and running a bottle of techron in the fuel.
I wouldn't worry too much about at this point. You can check the fuel pressure, if the regulator has a hose pull it off and see if any fuel is present if there is its gone.
Check the pressure with the hose on and off you should see a rise with the hose off.
Check the vacuum hose for leaks.
MAF is clean, I recently cleaned it and it was clean before as well. Techron gets run every once in a while (last bottle was 8K miles ago)
Originally Posted By: punisher
Nothing to worry about. Pay attention to SFT and LFT and notice under what conditions the SFTs change rapidly, or if they change rapidly. If it gets worse:
MAF concerns and fuel pressure (too high at idle) can mirror each other, rich idle trending leaner under load). Might be a good idea to take a look at the MAF hotwire and see if it has a case of the "fuzzies". Don't know if that year has an actual regulator or a returnless fuel system. Either hook up a fuel pressure gauge, or see if there is a fuel pressure PID available in your scanner software.
Relax.
Fuzzies?? - I hope not.
I am 99% sure it is returnless, yet there is a gizmo on the fuel rail with a vacuum tube going to it- Looking it up it is listed as Fuel Injection Pressure Damper- no idea what it is. The Fuel pump is new OEM if the actual regulator is in that.
Originally Posted By: Vikas
1) Check the air cleaner for restriction.
2) Check fuel pressure regulator or any vacuum hose connected to the regulator for leakage.
These are the the only two things which will make LTFT go negative. When MAF goes bad, it will usually read less and not more.
BUT, I have had -7% LTFT on my Maxima for a decade without any ill effect or tripping any codes. So there is really not much to worry about at this stage. If the MAF starts getting old, your LTFT would start becoming less negative!
Interesting you mention the Air Filter. I change it yearly and it is just shy of a year. I always use a MC Air filter, and I would normally get the FA1658, and this last time, they gave me the new part number FA1744. There are some differences between the two, and I haven't exactly been thrilled with this filter.
I am pretty sure the trims go to zero as I drive, but I'll look. It just seems to be at idle.