Quote:
Originally Posted by 1stnewcar
Interesting - do you know why? how much error there could be etc?
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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.