Air/Fuel ratios... is this normal?
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From: Hurley, VA
Air/Fuel ratios... is this normal? I just installed a wideband and honestly I have no idea what normal a/f ratios are. About all I know is the higher the number the leaner and the lower the number the richer. Well at idle my car goes full lean and displays - - - on the gauge. With just a touch of fuel it will drop into the 16s-17s but with constant 2k rpms it goes full lean again. If I stab say 1/4 throttle and let off it will go to somewhere in the 11.9-12.0 range and while driving and going wot it will drop into the high 11s low 12s and occasionally only down into the 13.0s. Is this normal? I'm confused about the fuel lean at idle and steady unloaded rpm, is it possible my wide band isn't accurate? Its a brand new AEM.
N/A car 12.5 to low 13's depending on the build.
Boosted cars 11.0 to 12.0 also depending.
Every car cruising is around 15.2. Most cars will fluctuate between 14.2 and 15.8 Nothing wrong with 16's or even 17's flickering every now and then.
Aem's usually never have problems or give in accurate readings. How does the car feel?
My innovate has been doing weird things lately. It pegs at 22.2 after the sensor heats up then all of a sudden goes to 12.8 until it warms up like normal. Also pegs 22.2 at wot as well now. Car is tuned and seems like it runs the same as always. Innovate sucks so far as my experiences have been.
Boosted cars 11.0 to 12.0 also depending.
Every car cruising is around 15.2. Most cars will fluctuate between 14.2 and 15.8 Nothing wrong with 16's or even 17's flickering every now and then.
Aem's usually never have problems or give in accurate readings. How does the car feel?
My innovate has been doing weird things lately. It pegs at 22.2 after the sensor heats up then all of a sudden goes to 12.8 until it warms up like normal. Also pegs 22.2 at wot as well now. Car is tuned and seems like it runs the same as always. Innovate sucks so far as my experiences have been.
Seems like you need to 1) get tuned and 2) check for exhaust leaks around the area where the wb is plugged into the exhaust.
As long as you have properly operating o2 sensors and fueling, there's no reason to be running that lean at part throttle. And since you're not getting codes for trims being lean, then you aren't really running that lean just the wb is being fed the wrong information due to exhaust leaks
As long as you have properly operating o2 sensors and fueling, there's no reason to be running that lean at part throttle. And since you're not getting codes for trims being lean, then you aren't really running that lean just the wb is being fed the wrong information due to exhaust leaks
Thread Starter
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From: Hurley, VA
Exhaust is actually brand new with band clamps around the header connections and they aren't even leaking the slightest bit. Is it possible I've got it to far away from the engine? Its welded in the first turn of the Y pipe on the passengers side and I have a 3" to 4" custom Y with a dynomax bullet dumped. Is it possible the exhaust isn't getting hot enough for the sensor since its so free flowing and far away?
There's no such thing as "too far from the engine"
with a LSU4 type wideband sensor. Its heat comes
from the controller and the controller needs to be
in charge. You could put it up the tailpipe if you
wanted to. So forget about that.
These widebands are as susceptible to spoofing as
the regular narrowband sensors. Any residual air in
the exhaust will bend the reading lean. You can get
this from cam overlap at idle, you can get it from
misfires anywhere in the operating range.
Now if that "bullet dumped" back end is only a couple
of feet past the sensor, that could hose your readings
by reversion. Might go get some extra flex pipe and
add it to the back, and see what that does to the
readings, apples-apples; if it makes a difference, then
there's your pony.
with a LSU4 type wideband sensor. Its heat comes
from the controller and the controller needs to be
in charge. You could put it up the tailpipe if you
wanted to. So forget about that.
These widebands are as susceptible to spoofing as
the regular narrowband sensors. Any residual air in
the exhaust will bend the reading lean. You can get
this from cam overlap at idle, you can get it from
misfires anywhere in the operating range.
Now if that "bullet dumped" back end is only a couple
of feet past the sensor, that could hose your readings
by reversion. Might go get some extra flex pipe and
add it to the back, and see what that does to the
readings, apples-apples; if it makes a difference, then
there's your pony.
Thread Starter
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From: Hurley, VA
I'll try the extra piping but the sensor is probably 2-3 feet behind the header collector and roughly a foot or so from the flowmaster merge and then roughly 2 to 2 1/2 feet of I pipe. So its at least 3 -4 feet away with 2 small bends between it. I didn't calibrate the sensor. I honestly didn't know you were suppose to. I thought power ground and hook up the 02 and it worked. If reversion is the problem would putting the sensor closer to the engine eliminate the problem? I'm assuming the reversion is the outside air being let into the exhaust and hitting the sensor.
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I didn't calibrate the sensor. I honestly didn't know you were suppose to. I thought power ground and hook up the 02 and it worked.
Try reading the instructions that hopefully came with the sensor, or look online on the manufacturer's website. It outlines step by step what you need to do from unpackaging the sensor to installation.
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Verdad Gallardo Thread Starter
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From: Hurley, VA
This is all I could find in the instructions and from what I get out of it (I'm an idiot). Its set to the right calibration on the default setting. I don't know what the nernst and what not means. They are a dial on the back of the gauge that reads P0, P1, P2 and so on.
Configuring Calibration Outputs
The AEM default position is (P0). When set to (P0) (Figure 10A), the gauge displays
AFR values. (P1) is the same as (P0), except the gauge displays lambda values. These
settings (P1 and P0) implement a linear calibration with the most useful voltage range
possible (0-5V). The AFR calibration (P2) is linear and similar to (P1) with a smaller
voltage range (1-2V). The AFR calibration (P3) emulates the Autronic Wideband O2
Sensor calibration (0-1V). The AFR calibration (P4) emulates a non-linear Nernst Cell
calibration (0-1V). Refer to the Table 3 and figure 9 for specific calibration details
Configuring Calibration Outputs
The AEM default position is (P0). When set to (P0) (Figure 10A), the gauge displays
AFR values. (P1) is the same as (P0), except the gauge displays lambda values. These
settings (P1 and P0) implement a linear calibration with the most useful voltage range
possible (0-5V). The AFR calibration (P2) is linear and similar to (P1) with a smaller
voltage range (1-2V). The AFR calibration (P3) emulates the Autronic Wideband O2
Sensor calibration (0-1V). The AFR calibration (P4) emulates a non-linear Nernst Cell
calibration (0-1V). Refer to the Table 3 and figure 9 for specific calibration details
Also it sounds like you are only 3 feet from the end of the exhaust, at lower engine speeds fresh air will actually be sucked up into the exhaust and this will cause the sensor to read lean. at higher rpm's it will read correctly as there will be enough exhaust to not let fresh air back in (reversion)
also just a note. it should idle at 14.7 and cruise down the road at 14.7, not 15.2 like mentioned above, unless you have turned on lean cruise or something. Narrow band sensors will always adjust the car to 14.7 as this is all they can read.
oh and with a new wide band always do a fresh air calibration.
also just a note. it should idle at 14.7 and cruise down the road at 14.7, not 15.2 like mentioned above, unless you have turned on lean cruise or something. Narrow band sensors will always adjust the car to 14.7 as this is all they can read.
oh and with a new wide band always do a fresh air calibration.
Thread Starter
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From: Hurley, VA
Well I called AEM and explained exactly how it acted. He said that I shouldn't get the display of - - -. He said it sounds like for some reason once the sensor got hot it was fouling out. He issued something (forget the name) for me to send the 02 sensor back for inspection and if it was bad he would send me a new one. And I asked about needing to calibrate it and he said it was preset that all I would have needed to have done was power, ground, and the 02.
it should idle at 14.7 and cruise down the road at 14.7, not 15.2 like mentioned above, unless you have turned on lean cruise or something. Narrow band sensors will always adjust the car to 14.7 as this is all they can read.
It's not even a matter of "perfection" - the sensor has
temperature based variation and a slopt to the transfer
function about stoich, and depending on where you set
the switching threshold you can pull idle AFR by a point
up or down, by changing the thresholds in the tune by
100-150mV.
You've got a multi-layer onion here and have to decide
what to trust. A consumer grade wideband does not
deserve absolute trust. Now if you had a near-stoich
reading up at (say) 3000RPM steady running, with the
narrowbands switching nice and tight, I'd call the
instrument good and look to other causes of error at
the low end. Such as the plumbing questions.
temperature based variation and a slopt to the transfer
function about stoich, and depending on where you set
the switching threshold you can pull idle AFR by a point
up or down, by changing the thresholds in the tune by
100-150mV.
You've got a multi-layer onion here and have to decide
what to trust. A consumer grade wideband does not
deserve absolute trust. Now if you had a near-stoich
reading up at (say) 3000RPM steady running, with the
narrowbands switching nice and tight, I'd call the
instrument good and look to other causes of error at
the low end. Such as the plumbing questions.
Thread Starter
10 Second Club
Joined: Jan 2010
Posts: 2,317
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From: Hurley, VA
Last night I played with what could be causing it and inspected my exhaust for leaks. I have absoultely no exhaust leaks anywhere on the system. Its a little less than a 1 1/2 feet from the header collector and I have about 4 feet of piping between the sensor and the end of the exhaust with two slight turns in that 4 feet. Holding steady throttle between 2500-3000 within say 20 seconds the gauge will start swinging lean and then display - - -. When the car is dead cold it seems to work fine for the first 30 seconds its running but then will go full lean and stop working.
Hey,just to let you know i am having the exact same issue with my AEM wideband, that is brand new out of the box. and my exhaust is all brand new as well and i have my wideband installed in my header collector on my drivers side. If you send your sensor into AEM, let me know what they say, because mine may be bad as well.
at initial start up and idle it will read fine for the first 2-3 minutes, but the it will start acting wacky and sweeping everywhere, and when driving it will go full lean and ----- out on me and go back and forth between reading, and that
Yea please do. i know its not a install error on my part, 12v switched power, and chassis ground are hooked up right. 02 sensor is installed in the bung that is in my kooks headers. I know i dont have a exhaust leak in my headers. I have new kooks true duals installed and i have not checked for a leak downstream since i installed them, but i would think that the leak would have to be before the sensor not after to lean it out that much.
