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maffrequencylimits [2009/07/20 07:59]
twdorris
maffrequencylimits [2009/07/20 08:00] (current)
twdorris
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-===== GM MAFs ===== 
  
-The two most common ​GM MAFs used on our DSMs are the 3" and 3.5" MAFs, part numbers 25180303 and 25179711, respectively. ​ These sensors ​operate fundamentally different than the Mitsubishi MAFs.  The GM MAFs work by measuring mass airflow directly. ​ They do not need temperature and baro data because they'​re not measuring volume. ​ They are reporting air mass directly as a frequency.+===== GM MAF sensors ​=====
  
-The biggest problem, IMO, with these MAFs is that this frequency to mass mapping is non-linear. ​ So as airflow increases, it takes less and less change in frequency to present a larger and larger change in air mass.  This makes the system very sensitive to fluctuations in frequency output from the sensor.+The two most common GM MAF sensors used on our DSMs are the 3" and 3.5", part numbers 25180303 and 25179711, respectively. ​ These sensors operate fundamentally different than the Mitsubishi MAF sensors. ​ The GM MAF sensors work by measuring mass airflow directly. ​ They do not need temperature and baro data because they'​re not measuring volume. ​ They are reporting air mass directly as a frequency. 
 + 
 +The biggest problem, IMO, with these MAF sensors ​is that this frequency to mass mapping is non-linear. ​ So as airflow increases, it takes less and less change in frequency to present a larger and larger change in air mass.  This makes the system very sensitive to fluctuations in frequency output from the sensor.
  
 Neither a MAF Translator nor the ECMLink V3 GM MAF cable allow you to see the raw GM MAF sensor frequency directly. ​ The MAF Translator provides a translation to stock DSM-like frequencies,​ while the ECMLink V3 GM MAF cable provides a simpler translation that produces raw frequencies that are quite different (but that the ECMLink V3 ECU code knows how to handle). ​ So it's best to avoid talking about limiting-frequencies when discussing a GM MAF sensor when used on a DSM and rather just talk about air-mass metering capability. Neither a MAF Translator nor the ECMLink V3 GM MAF cable allow you to see the raw GM MAF sensor frequency directly. ​ The MAF Translator provides a translation to stock DSM-like frequencies,​ while the ECMLink V3 GM MAF cable provides a simpler translation that produces raw frequencies that are quite different (but that the ECMLink V3 ECU code knows how to handle). ​ So it's best to avoid talking about limiting-frequencies when discussing a GM MAF sensor when used on a DSM and rather just talk about air-mass metering capability.
maffrequencylimits.txt · Last modified: 2009/07/20 08:00 by twdorris