ARM1 or AF9
02-28-2004 | 09:38 AM
#1
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From: Los Angeles
ARM1 or AF9
has anyone tried mounting ARM1 or AF9 on their cars? both of which are air/fuel mixture indicator.. anyway, when i start and warm up my car, the led bar stays on 5 ...but when the car actually warms up and running, the bar keeps going left and right ..it's not stable ... is it supposed to be like that? is there something wrong with the fuel mixture?
02-28-2004 | 09:43 AM
#2
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post this on the turbo board, a lot of those guys have used ARM1
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02-28-2004 | 12:57 PM
#3
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From: Santa Barbara, CA
"but when the car actually warms up and running, the bar keeps going left and right ..it's not stable ... is it supposed to be like that? is there something wrong with the fuel mixture?"
That's correct. It's the computer continually re-adjusting the air-fuel mixture so that it's stays centered around 14.7:1 air-fuel ratio on average. It's a Heisenberg Principle or sorts when it comes to measuring the reading at the O2-sensor. Due to time-delays and different distances, there's no way to do an you can analyze the mixture that's burning in the combustion chamber and at the same time, make adjustments.
So the O2-sensor reads the output over 5-feet after the combustion chambers, which is after the fact. Then the computer makes an adjustment at the injectors, which is 5-feet away from the O2-sensor. However, the computer is not even calculating fuel for the air that's going into the engine right now. It's calculating that based upon air-flow readings of air another 5-feet way at the AFM. Which will take another 10-15 engine revolutions to make it into the combustion-chambers. So you've got three far-fetched locations where different stuff is happening. So the computer makes an adjustment, then measures the result, then adjusts the other way to compensate and back & forth. It's perfectly normal!
Now with more modern computers, this dithering action back and forth occurs much, much faster. Such that the back& forth motion becomes almost a blur and the extreme ranges at each end is also much tighter.
That's correct. It's the computer continually re-adjusting the air-fuel mixture so that it's stays centered around 14.7:1 air-fuel ratio on average. It's a Heisenberg Principle or sorts when it comes to measuring the reading at the O2-sensor. Due to time-delays and different distances, there's no way to do an you can analyze the mixture that's burning in the combustion chamber and at the same time, make adjustments.
So the O2-sensor reads the output over 5-feet after the combustion chambers, which is after the fact. Then the computer makes an adjustment at the injectors, which is 5-feet away from the O2-sensor. However, the computer is not even calculating fuel for the air that's going into the engine right now. It's calculating that based upon air-flow readings of air another 5-feet way at the AFM. Which will take another 10-15 engine revolutions to make it into the combustion-chambers. So you've got three far-fetched locations where different stuff is happening. So the computer makes an adjustment, then measures the result, then adjusts the other way to compensate and back & forth. It's perfectly normal!
Now with more modern computers, this dithering action back and forth occurs much, much faster. Such that the back& forth motion becomes almost a blur and the extreme ranges at each end is also much tighter.