A/F ratio
 

I logged some air fuel ratio after reading about having Mods without getting a tune. Below are 3 main screen grabs I thought can be useful. I don't know how accurate these are, I used OBDII + Torque app

Idle
http://i35.photobucket.com/albums/d1...ps1d138d52.jpg


20% to WOT
http://i35.photobucket.com/albums/d1...ps5d45b4d5.jpg

6th Gear 100+KM/h throttle on/off. reading goes all the way up when I let off throttle
http://i35.photobucket.com/albums/d1...psbc2237f2.jpg

Does this look normal? anyone knows a better way to use the torque app?

depends on whats going on within those dips.

At idle and low load, it's going to hover around 14.7:1.

On tip in, AFR might enrichen (or briefly skew lean, then enrichen, which I believe is what you found in 20% TPS to WOT), then move towards target (depends on load -- richer at moderate to high load).

On throttle lift, fuel will cut, so it will read lean on coast down, returning to stoich as you approach idle.

Anyway, unless you have changed the diameter of the MAF tubes from OEM, or have a sensor issue or vacuum leak, it should trim (without issue) to various targets in ECU fueling map, depending on load, air temps, oil temps, etc.

When trims get too high, you'll get a CEL.

EDIT: Everything you posted looks normal...

Pick up this book http://www.amazon.com/Engine-Managem.../dp/1932494421

You will learn a LOT about tuning and be much more able to interpret sensor data :tup:

Thanks Jordo! So I'll skip the tune for now :)

:tiphat:

What are your mods?

You can almost definitely leave things alone, at least based on those brief snapshots, but you can probably milk more power and improve driveabilty over stock with a tune.

You might also data log Long term fuel trims to see how much correction the ECU is applying. If you can log two parameters (say, load or MAF voltage along with LTFT's or AFR) it will be easier to see if there's someplace with room for improvement. Another good variable to log is ignition timing.

You always want to have a load reference point (you sort of did that informally by noting "idle", vs "low load to WOT" vs "tip-in" vs "throttle lift"). You could also use TPS to scale, but load or MAF voltage will be better.

If you have only a catback and OEM airbox with high flow filters and/or smooth tubes, you should have very nominal trims. If you have a CAI, or anything that replaces the cat, it's a bit more hit and miss.

I have the basic stuff: CBE, HFC, drop in filters+tubes. I'll post more logs when I get a chance. Appreciate the help :tiphat:

If this is a weekend warrior, its not so.bad if u don't tune it.
If this is your DD...i would highly recommend a tune with those mods brother:driving: