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The Terminator
Engine/Tuning
Self Tuning With SCT Pro Racer
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<blockquote data-quote="JAJ" data-source="post: 16415411" data-attributes="member: 131874"><p>The ECU uses manifold volume to calculate how long it waits to increase or decrease fuel injector timing after the throttle position changes. If you're idling with the throttle almost closed, and then you open the throttle, it takes a while for the manifold to fill up with air (it's only milliseconds, but it's not instantaneous), and the manifold volume number tells the ECU how long it needs to wait before increasing fuel flow. If the volume setting is set too high, the fuel delivery change that follows a throttle movement will happen too late and you'll have a lean surge. If the volume is too small, it'll happen too fast and you'll have a moment of richness. The difference is milliseconds, but it affects driveability at low throttle openings (like city driving). It doesn't matter as much at higher throttle openings because once the bypass valve closes, everything changes.</p></blockquote><p></p>
[QUOTE="JAJ, post: 16415411, member: 131874"] The ECU uses manifold volume to calculate how long it waits to increase or decrease fuel injector timing after the throttle position changes. If you're idling with the throttle almost closed, and then you open the throttle, it takes a while for the manifold to fill up with air (it's only milliseconds, but it's not instantaneous), and the manifold volume number tells the ECU how long it needs to wait before increasing fuel flow. If the volume setting is set too high, the fuel delivery change that follows a throttle movement will happen too late and you'll have a lean surge. If the volume is too small, it'll happen too fast and you'll have a moment of richness. The difference is milliseconds, but it affects driveability at low throttle openings (like city driving). It doesn't matter as much at higher throttle openings because once the bypass valve closes, everything changes. [/QUOTE]
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