engineermike
Well-Known Member
@Angrey you are correct that the pedal position generally correlates to a torque demand and the pcm determines what throttle angle (cam timing, spark, etc) it takes to make it. Depending on rpm, manifold vacuum, and ambient conditions (or throttle inlet pressure in the case of the ecoboost), the resulting angle could vary greatly from pedal position.
Lots of funny things are going on with spark timing during tip-in, so I won’t go into all that.
For throttle control during tip-in, it’s still controlling torque. There’s your managed tip-in/anti-jerk/oscillation that actually slows response some, to smooth it out a bit. If you log torque source you can see it use oscillation for a moment when you first tip-in. Many tuners turn this off but it’s not a dramatic difference.
Then there’s manifold volume effects. The pcm actually determines the manifold plenum filling rate and how that affects cylinder filling. If the manifold volume is tiny, then it slows down blade response. If the plenum is large, it tips the blade open quicker initially then cuts back. But the goal is still the same; to accurately get a very specific cylinder filling to achieve desired torque.
@Rolls I believe there an ac compressor cutoff as a function of rpm as well.
Lots of funny things are going on with spark timing during tip-in, so I won’t go into all that.
For throttle control during tip-in, it’s still controlling torque. There’s your managed tip-in/anti-jerk/oscillation that actually slows response some, to smooth it out a bit. If you log torque source you can see it use oscillation for a moment when you first tip-in. Many tuners turn this off but it’s not a dramatic difference.
Then there’s manifold volume effects. The pcm actually determines the manifold plenum filling rate and how that affects cylinder filling. If the manifold volume is tiny, then it slows down blade response. If the plenum is large, it tips the blade open quicker initially then cuts back. But the goal is still the same; to accurately get a very specific cylinder filling to achieve desired torque.
@Rolls I believe there an ac compressor cutoff as a function of rpm as well.
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