LTFT's (again)

[Plums]

What is the ideal LTFT value?
I've read that neg at idle and part throttle, and zero WOT seems to be the go, but what neg value is the best? Does it matter as long you have zero at WOT?
I assume you should aim for as close to zero as possible while still retaining zero at WOT???

My current tune has them well into the negatives (-10 at idle).

Any thoughts?

Cheers,

Plums...

[CatSkynr]

Different strokes, different folks.

#1 priority: 0 KR

My ‘personal’ settings set my FTCs 6-14 average LTFTs @ (-3). That got my car where it wanted to be. “Ideal” is 0 in a perfect world. That means that the car is running 100% spec, fuel is 100% spec and the weather never changes. (I want to live in this world!) The internal combustion engine is a complex, dynamic collection of different systems working together to convert the stored power in gasoline into mechanical energy to push a car down the road. Any variation in one of these systems will also indirectly affect the other systems, as well. 0 means that the PCM doesn’t need to make any adjustment to ‘compensate’ for variations in this system. So I would say the ‘accepted’ value to shoot for is as close to 0 as possible somewhere on the negative side. It is better to run rich, than it is to run lean.

[jimmyblue]

Idle has a lot of nonidealities at play - running partly
on SD inputs (which is why messing VE around has
effect, for your post-cam tuning, etc.), O2s barely lit,
and so on.

The midband, but below PE MAP threshold, cells are
a better indicator of the "normal" MAF and fuel tables'
combined accuracy. That would be cells 0,1, 2, 3 if you
have the stock MAP=15 threshold, and on an F-body
you will never see cells 2&3. So that kinda narrows
that down; Cell 1 is the indicator of baseline accuracy
in metering.

Above that you see the PE coming in and affecting the
trims, depending on you fat it's made, how early. I know
trimming is supposed to cease once a =/=1 multiplier
is in play but I've seen the Predator push my upper-
FTC trims around, substantially. So ???

I have -7-10 LTFTs at idle too, and pretty much disregard
that set of cells; they don't relate much to the primary
interest. As long as there's still plenty of room for the
PCM to adjust them right (the limits are +/-25%) there
is no particular reason to fuss over these - they just
have to get by.