Don Terrill’s Speed-Talk

I've not seen "pure alpha N" used in....probably 20+ years because it just doesn't work very well. I think it died with 8 bit ecus. All recent implementations include an air temp and pressure ....but that doesn't make it SD, it makes it functional.

The pressure used is normally barometric, but MAP can be used and in that case, it does become a blend of alpha-N and SD. I've tried this before, some ecus love it, others not so much.

mk e wrote: ↑Wed May 09, 2018 7:17 am I've not seen "pure alpha N" used in....probably 20+ years because it just doesn't work very well. I think it died with 8 bit ecus. All recent implementations include an air temp and pressure ....but that doesn't make it SD, it makes it functional.

The pressure used is normally barometric, but MAP can be used and in that case, it does become a blend of alpha-N and SD. I've tried this before, some ecus love it, others not so much.

I wonder when a "pure" alpha-N (as Grumpy calls it) last rolled off the factory assembly line. Ever?

For a turbo ITB engine, it would in my opinion make sense to measure load using both Alpha-N (with the standard temperature and pressure corrections from measurements upstream of the throttle plates) and manifold density (measuring pressure and temperature from a vacuum/pressure manifold downstream of the throttle plates) and then blend those two with different weights.

Explanation on ITB-mode can be found here : http://www.msextra.com/doc/pdf/html/Meg ... p-1.5.html

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