03-24-2010, 06:40 PM
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#11 (permalink)
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A True Z Fanatic
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Quote:
Originally Posted by stormcrow
The point that you are missing is that even though you may be able to tune for the miscalculated intake air temps to quell knock, these are canned tunes at sea level and in different ambient temps. The ECU, in situations like this, need to be able to adjust for variables. Without knowing the exact temperature of the air from the MAF (measuring colder are due to 'draw through' that does not equate the hotter, compressed air going into the intake) the ECU cannot make the adjustments. This is why a "blow through' setup on a canned tune is a better option (though not close to perfect) than a canned tune on 'draw through'.
It's all well and good to have a custom tune on an OEM N/A car using 'draw through', but when it's a singular map shipped all over the world and in drastically different environments, not so much. This setup should come with a warning of recalibration is recommended. We've had this debate over on NAGTROC quite a bit when discussing "e-tunes." Even on an OEM F/I car that is calibrated for 'draw through', a one-size-fits-all approach to tuning is a bad idea.
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Oh I definitely agree that it is much better to have engine custom tuned, I missed that that was the issue, I thought you were just worried about the MAF location.
But that aside what they probably do on a canned tune is run the engine hot and then make sure they tune for the save side (compensate for the real air temp, compared to the measured), you'll loose some power, but avoid ruining your engine. Additionally you've got a feedback loop from for instance the knock sensors which the ecu will use for self-learning and will use to compensate. Finally I don't know the algorithms that the Nissan ECU will use, but on top of the standard measures the car has VVEL, so it has some pretty powerful potential to compensate. Too bad this hasn't been cracked so they can make this custom as well, but I'm sure even the standard algorithms will assist here.
As Stillen is the one who actually does the canned tune, maybe they can comment on their approach. Maybe my above description is totally off, this would just be how I would do it.
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