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mass air flow

EFI Tuning Fundamentals

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Discussion and questions related to the course EFI Tuning Fundamentals

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I didn't see where he said how to recalibrate the mass air flow after changing air intake components. Please give me some more information. Also curious how i can tune without a dyno.

If you could give some idea why you feel the AFM would need re-calibration?

You can get a rough tune by checking lambda (AFR) and listening for detonation/pre-ignition, some ECUs will log/warn of the latter which helps. If you're looking at something like sprints, where you have elapsed time and trap speeds to compare, or speeds at different parts of a track or climb to compare, it helps. Then there's driveability - idle, light throttle, cold/hot running, etc.

You can reduce dyno' time by getting an approximation on the street, but it's just that, an approximation, and you may be leaving a lot on the table.

On GM with 6.0LS engine, how do i recalibrate the maf sensor after changing intake piping from air filter to intake manifold? after changing piping the engine runs horrible. changed frequencies out of just guessing and it runs better, but like to know the proper way to recalibrate correctly.

Do you mean when the size of the intake piping has been changed?

To get the calibration in the ball pack, you need to calculate your intake tube area change using basic maths. ie. π x radius (squared)

So if you go from a 2.5in pipe to a 3in pipe

2.5in area = π x 1.25(squared) = 4.9087in

3.0in area = π x 1.5(square) = 7.0685in

Difference in area is: 7.0685 - 4.9087 = 2.1598in

Percentage increase is: (2.1598 / 4.9087) x 100 = 43.999%

So for a given frequency you will have 44% more air passing the sensor.

ie. if 50hz previously = 5.86g/s

then 50hz will now = 8.43g/s

Where this gets ugly is dependant on how accurate the sensor is, and how much airflow it needs across the element to give an accurate reading. If the pipe increase is dramatic, you may have very little air speed across the element, and the 44% will not be accurate. You will also run into issues it the sensors location is more or less prone to turbulent air than the original pipe.

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