The FIA has closed a loophole that allowed Red BullRed Bull RB8Austria, 2012 > 201210 photos
to decrease torque and increase engine emissions in the middle RPM range. The exploit allowed Red Bull to decrease wheel spin and allowed more gases to exit the car to affect aerodynamics. 

The new rules will force teams to nominate an engine map must the first four races of the season as a benchmark for the rest of the season. The engine maps for all subsequent races must match the original to within 2% when above 6000rpm.

The new rule allows for teams to ask for exceptions during "exceptional atmospheric conditions."

"Obviously we had what we had in the car in Hockenheim because we believed it was quickest, so it is a little bit different for here. But it is hard to give you a figure: if it is two tenths, half a tenth, or nothing. We cannot measure," said Sebastian Vettel. 

The problem with the whole situation is that Red Bull was not technically breaking the rules. There was no rule covering what it was doing, and it was exploiting that. The rule only said that the relationship between the throttle position and torque curve must be linear. The Red Bull engine map limited torque but did not decrease it. 

Source: Autosport (1,2)