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Old 10-31-2009, 02:15 PM   #118
Scooby Specialist
Member#: 163445
Join Date: Nov 2007
Chapter/Region: MWSOC
Location: Effingham IL (Central IL)
l33t *******


You need to be able to tune your car from scratch to use this SD rom.... Plain and simple.

Here is my best explanation.

Maf based systems meter the amount of air ingested into the engine based on density/volume. A maf sensor should not need to be compensated for intake air temperature changes, when you see a compensation this is more for the engines volumetric efficiency @ a given temperature. << Last sentence is my thoughts on it.

Speed density does not know how much air is ingested nor the density. It simply knows the pressure at which the manifold is at. You, using the speed density load compensation map and intake air temp compensation determine the density of the air at a given manifold pressure in absolute form.

Your speed density map should look relevant to your engines VE at a given manifold pressure. Below 14.7psiA your peak torque is going to be a higher value because of cam design and general engine design. Using speed density YOU must determine the airflow and density of the air.

In the end the same value is used to determine fuel injector pulse width, Grams of air per revolution. In the end that is simply all that matters, using SD is just using a different sensor and a different approach to determine how many grams of air per revolution you are at.


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