A/F ratio

zefaulter · 10-03-2014, 12:58 PM

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

20% to WOT

6th Gear 100+KM/h throttle on/off. reading goes all the way up when I let off throttle

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

iceman21_23 · 10-03-2014, 01:39 PM

depends on whats going on within those dips.

Jordo! · 10-03-2014, 02:37 PM

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

zefaulter · 10-03-2014, 05:41 PM

Quote:

Originally Posted by Jordo!

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

On tip in, it might enrichen (or briefly skew lean), 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

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

Jordo! · 10-03-2014, 06:09 PM

Quote:

Originally Posted by zefaulter

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

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.

zefaulter · 10-03-2014, 11:29 PM

Quote:

Originally Posted by Jordo!

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

Luciano13 · 12-07-2014, 04:06 PM

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

10-03-2014, 12:58 PM	#1 (permalink)
zefaulter A True Z Fanatic Join Date: Jan 2013 Location: Toronto, Canada Posts: 1,983 Drives: 40th 370Z Rep Power: 27	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 20% to WOT 6th Gear 100+KM/h throttle on/off. reading goes all the way up when I let off throttle Does this look normal? anyone knows a better way to use the torque app?

10-03-2014, 01:39 PM	#2 (permalink)
iceman21_23 Track Member Join Date: Jan 2009 Location: league city, tx Posts: 757 Drives: 09' Solid Red 370z Rep Power: 17	depends on whats going on within those dips. __________________ Zele front bumper cf front lip, Seibon TS Hood, Work GS2, Ings+1 side skirts Takeda CAI Litespeed Exhaust

10-03-2014, 02:37 PM	#3 (permalink)
Jordo! A True Z Fanatic Join Date: May 2010 Location: nirvana Posts: 6,394 Drives: 2023 NATM Rep Power: 418	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 GaleForce, zefaulter and olddudesrule like this. __________________ Enjoy it. Destroy it. Last edited by Jordo!; 10-03-2014 at 06:15 PM.

12-07-2014, 04:06 PM	#7 (permalink)
Luciano13 A True Z Fanatic Join Date: Mar 2013 Location: Canada Posts: 2,130 Drives: 2016 Solid Redz Rep Power: 245	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 zefaulter likes this. __________________ http://www.the370z.com/members-370z-...lid-red-z.html

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