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      03-18-2008, 03:52 AM   #124
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England
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Drives: see above.
Join Date: Apr 2005
Location: Yorkshire, UK

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2005 320D SE  [10.00]
2005 645  [9.00]
Quote:
Originally Posted by Ti Rich View Post
Becuase the MPG is normally calculated by the injector pulse width (open time) for a given fuel pressure. The tuning box fools the ECU to run at a higher pressure but the ECU doesn't see the actual pressure. Running the same injector pulse width at a higher pressure will use more fuel.

Remapping normally ajusts the pulse width keeping the fuel pressure the same so the MPG calc is accurate.

I can't say 100% it's the case with this tuning box but on all the ones i have used before the MPG was 5-15% optimistic. Only way to check is to do a manual calculation.
Thanks - I didn't know this. Anyone with the box done any calculations?
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