IS MAF Freq output proportional to air volume?
04-09-2005, 06:36 PM
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IS MAF Freq output proportional to air volume? I'm getting P103 after WOT (wheelspin) in 1st gear. I do run a K&N & have for about a year. I cleaned the inside of the MAF with a little Brakeclean & compressed air. This has started this spring, maybe coincides with LSX install & recent tune. Using my HP Tuners logs from last year compared to this year I see my MAF Air Flow is up from about 39lb/in last year to 41lb/in this year at near red line (6800 RPM). Changes are LSX intake & reworked exhaust. I'm thinking of scaling my MAF fail threshold up by about 5% to cover the increased airflow, is this correct? The threshold is currently set at 23040. Any guidence will be appreciated.
04-09-2005, 06:52 PM
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Originally Posted by Mark98SS
I'm getting P103 after WOT (wheelspin) in 1st gear. I do run a K&N & have for about a year. I cleaned the inside of the MAF with a little Brakeclean & compressed air. This has started this spring, maybe coincides with LSX install & recent tune. Using my HP Tuners logs from last year compared to this year I see my MAF Air Flow is up from about 39lb/in last year to 41lb/in this year at near red line (6800 RPM). Changes are LSX intake & reworked exhaust. I'm thinking of scaling my MAF fail threshold up by about 5% to cover the increased airflow, is this correct? The threshold is currently set at 23040. Any guidence will be appreciated.
04-09-2005, 07:03 PM
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If the MAF is failing does that mean it's going into SD mode? If so why is the car still as quick as last year? Or could the new mods be making up the difference?
04-09-2005, 07:04 PM
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Originally Posted by Mark98SS
"103 - Mass Air Flow (MAF) Sensor Circuit High Frequency", straight from HP Tuners. I assume more air flow = higher frequency?
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04-09-2005, 09:28 PM
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Changing your MAF fail threshold is not needed. It is like changing your gas cap because your a headlight is out. Your change in airflow is because you are making more power, and your engine is breathing better. Unless you trims were affected, there are no changes to make. Your MAF frequency output is directly proportional to airflow through the MAF, however the MAF is not always accurate, and unmetered airflow can get past. If your MAF fails you car falls back on dynamic airflow or "SD", and you will end up riding the low-octane fuel table. It sounds like you have a bad MAF. The only way you are going to max out your MAF is with forced induction.
04-09-2005, 09:43 PM
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Frequency increases with airflow but it's not proportional in a
linear sense. The function looks more logarithmic, a power
series fit comes out messy.
According to the Helm book P0103 sets if the MAF frequency
is greater than 13500Hz for more than 1.2 seconds. It
mentions that water getting into the MAF could cause the
code (water I suppose grossly cooling the sense resistor
and wanting more heater power = frequency than makes
sense). Also says that a poor connection in the "Ignition 1"
voltage circuit can cause DTCP0103 to set. Lastly it
mentions that EMI can induce this problem and warns
against the harness being routed near solenoids and spark
plug wires.
linear sense. The function looks more logarithmic, a power
series fit comes out messy.
According to the Helm book P0103 sets if the MAF frequency
is greater than 13500Hz for more than 1.2 seconds. It
mentions that water getting into the MAF could cause the
code (water I suppose grossly cooling the sense resistor
and wanting more heater power = frequency than makes
sense). Also says that a poor connection in the "Ignition 1"
voltage circuit can cause DTCP0103 to set. Lastly it
mentions that EMI can induce this problem and warns
against the harness being routed near solenoids and spark
plug wires.
04-09-2005, 10:07 PM
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Originally Posted by jimmyblue
Frequency increases with airflow but it's not proportional in a
linear sense. The function looks more logarithmic, a power
series fit comes out messy.
According to the Helm book P0103 sets if the MAF frequency
is greater than 13500Hz for more than 1.2 seconds. It
mentions that water getting into the MAF could cause the
code (water I suppose grossly cooling the sense resistor
and wanting more heater power = frequency than makes
sense). Also says that a poor connection in the "Ignition 1"
voltage circuit can cause DTCP0103 to set. Lastly it
mentions that EMI can induce this problem and warns
against the harness being routed near solenoids and spark
plug wires.
linear sense. The function looks more logarithmic, a power
series fit comes out messy.
According to the Helm book P0103 sets if the MAF frequency
is greater than 13500Hz for more than 1.2 seconds. It
mentions that water getting into the MAF could cause the
code (water I suppose grossly cooling the sense resistor
and wanting more heater power = frequency than makes
sense). Also says that a poor connection in the "Ignition 1"
voltage circuit can cause DTCP0103 to set. Lastly it
mentions that EMI can induce this problem and warns
against the harness being routed near solenoids and spark
plug wires.
04-10-2005, 09:36 AM
#16
just use this spreadsheet, it's something me and TXhorns281 figured out like 2 months ago (and btw, i got a new version out, it does historical compounding of data, check it out everybody)
http://www.allmod.net/hpt/
http://www.allmod.net/hpt/
