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Its determined via manifold pressure, air speed and throttle position. Obviously temperature is involved, but assume the engine is up to temp.
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Good work...
But temperature of the inlet charge IS involved at all times....even if only to ****** timing as temperature climbs.
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Obviously at the same time the MAF, temp, MAP, knock sensors etc are monitoring the situation so the ECU knows how much ignition advance and fuel to supply as well.
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...and inlet temperature, and - I'm led to believe -the ESP system is tied in, monitoring wheelspin and torque shift to maximise throttle opening vs requested throttle where there is grip available to utilise the torque..where the wheels spin, the ECU throttles back to re-gain grip - on ESP equipped card obviously.
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As far as I know the system doesn't measure how quickly the throttle plate turns as the MAP will know due to the pressure changes.
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I believe it does...
I think the system knows how quickly the throttle is opened by the drivers right foot, and will attempt to match the desired throttle opening as long as grip is available and the engine parameters are acceptable.
Assuming all the engines parameters are OK, the ECU will open the throttle plate in line with the requested position (although it may be slower, or even faster, if all other parameters are in a healthy state)
As for measuring how fast the throttle plate turns, the ECU knows this by having the throttle body calibrated (Adaptation in VAG Com talk) for closed and wide open - assuming the TB is not faulty the ECU then knows it's 'zero' point, and 'full span' point, and can assume with reasonable accuracy that a signal 50% of the way between will equate to 50% throttle opening.
I believe the MAP, MAF, TB position, pedal position, knock sensor, charge temperature, coolant temperature, N75 and engine speed (and ESP inputs on such equipped cars) are all used to determine the power delivery based on the revs/fuel/ingition/boost maps.
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DBW engines are slightly less intelligent as they do not have the MAP sensor. I think this type rely more on the MAF and throttle position. Not read up much on these (even though I have one!!).
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Did I read you right there?
DBW LESS intelligent?
Surely not...
DBW cars have a MAP sensor...on the S3 it's in the hard boost pipe from the second SMIC to the TB.
Look at the control algorithms for a DBW car (also an ESP car) and they are far more advanced than a non-DBW car...and far more intelligent....although the ECUs ability to regulate throttle position relative to its control parameters and not always what you want it to do, can (and do) make for slightly erratic behavoiur.
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Hope that helps a bit, and someone correct me if I've got it all wrong
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...and correct me if I'm wrong too... /ubbthreads/images/graemlins/smile.gif
