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A/f Ratios

|PRESA|

By |PRESA|,
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|PRESA| Proficient

|PRESA|

Posted
Posted

I just fitted an A/R Ratio gauge and it's showed me something thats concerned me a bit..

On idle or if I'm driving then release the throttle completely it runs all the way towards Lean and then off the LED dial thingo.. Does it mean that it's running that lean??

Cos thats surely not a good thing right?

I just had a PFC fitted and tuned and when the car is hot it makes a funny noise out the exhaust on idle - it's not like a clean idle it sorted makes a popping sound or gargle.

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Duncan Grand Master

Duncan

Posted
Posted

It is very normal to run lean on a trailing throttle. You only need to run nice and rich at full throttle, in normal driving the O2 sensor is designed to run the ECU at around 14.1

And assuming you have a AFR gauge running off the standard O2 meter, they aren't much use :D The gauge is only accurate around 14.1, it can't accurately measure 10 v 11 v 12 etc etc

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elbee111 Proficient

elbee111

Posted
Posted

I would tend to trust the tuner, but.....

My Apexi turbo timer shows A/F ratios while running, and shows lean as when you back off going down a hill for instance. I beleive that this is nothing to worry about at all.

Your guage showing lean on idle is something that I am not familiar with as mine shows mid 14's on idle.

All the best.

El Bee

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PHaT MR30 Grand Master

PHaT MR30

Posted
Posted

yeh remember that a normal o2 sensor only reads a 1 volt spectrum of accuracy... i wouldn't pay much attention to it

we had a mates old soarer on the dyno a few weeks back which was doing weird stuff according to an autometer a/f guage, and yeh found it to be perfectly normal to go lean on decelleration and idle (mind you on the high side of lean)...

read Sydneykids article on the Tech Edge wide band A/F thingo

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raz0r$harP.UK Grand Master

raz0r$harP.UK

Posted
Posted

^^ Yeah I know that, but (as I only realised the other day), you are supposed to enter the A/F and O2 sensor parameters on the Auto Timer so it can properly estimate the A/F..otherwise you'll end up like mine where it constantly flashes '---'

eg A/F can be 'set' between 10-and 20

and the 02 sensor voltage between 960 and 002

Would you mind taking a look on yours and telling me what it's set to?

//edit: all I need is for you to is

1. While A/F selected, hold the knob to the right and tell me what it's set to

2. Hold knob to the left to cancel adjustment

3. Move down to display O2 sensor voltage, hold knob to right and get the setting for me.

4. Hold knob to the left to cancel adjustment

It's straight from the AutoTimer instructions.. I'm just not sure what they should be set to on skylines..

Thanks! :)

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benl1981 Grand Master

benl1981

Posted
Posted (edited)

on decel - i.e as soon as you take your foot off accelerator fuel is cut. i.e no injectors are pulsed

Therefore 02 sensor voltage = 0 i.e. completely lean - i.e. there is no problem.

Cars use this to pass emissions and increase fuel efficiency

Edited by benl1981
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Sydneykid Grand Master

Sydneykid

Posted
Posted
I just fitted an A/R Ratio gauge

Waste of time and money, disconnect it and move on with your life.

:) cheers :)

PS; obviously this doesn't apply to fast and wide lambda sensors and properly calibrated A/F ratio meters.

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rob82 Mentor

rob82

Posted
Posted

Have seen them play havoc as well with standard computers ie poor grounding/wiring leading to wrong voltage bias on narrow band O2 sensors. Its always cool when the standard computer is trying to trim the wrong amount of fuel in or out.

We use this ability of altering the 02 sensor bias with our Xede processor to enable a lean cruise function(with the right conditions of course).

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Sydneykid Grand Master

Sydneykid

Posted
Posted
We use this ability of altering the 02 sensor bias with our Xede processor to enable a lean cruise function(with the right conditions of course).

we.....our.......Xede :)

Oh goody, someone who knows about Xede's.

I feel a new thread coming on.

:) cheers :)

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