High LTFT after filter

[Kelp]

Common problem. I noticed this on idle, the WB AFRs are ok open loop and WOT.

After a low resistance filter the LTFTs go (+). As an experiment I removed my air filter to simulate this. Sure enough (for whatever technical reason = I do not care) LTFTs go (+). Maybe up to 15. This is from idle through some RPMs until I go into open loop. Ah so!

I don't think this is harmful, but I like a fuel trim to be as it was intended. Isn't that why they call it "trim"?

I was going to adjust via the "MAF calibration". Simplest most direct route, the other tables are complicated. I have a C6 Z06, so no VE tables.

Any thoughts?

[EC_Tune]

Log a bunch of data and look at the (+) Max values and the (-) Min values at lower airflows. If the range is greater than 15 the hi flo aircleaner is giving the sampling MAF fits. No solution that I have heard of for that problem though...

[Kelp]

Good reasoning. I tried a bunch of various resistance filters, including none, at the intake. Competely open, and free from proximity of obstacles, the MAF reads +10 to +15. With just a _little_ bit of resistance, it resumes in the normal negative range. -2 to -8 where I have it tuned.

I'll research for references about this odd behavior but it might be hard to find. One concern is that popular air charger systems may push the MAF into this range easily and unwittingly to the user.

Fortunately the VCU can compensate, but being compensated already, it does not have far to go until it moves more dangerously lean.

[EC_Tune]

Problem I and a couple others had with an early air charger system was bucking at low throttle. I think they have worked on it and may have a better solution today.
I can see where the sampling MAF's in the 2006 Z06 giving CAI companies fits. Any turbulence induced ahead of the sampling MAF will result in odd fueling issues depending on where the turbulence occurs.

Can't wait for a VE tune fix for these bad boys!