I don't know about anyone else but when I down shift my car revs up not down. I have a 6MT and when my engine rpm's spiked I had my clucth all the way down. I thought it was my foot catching the gas pedal as I was braking, but it happened a couple times.

As the RPM spikes it puts more presure on the brakes to stop so why would it make sense to down shift durring braking. Imo the car should not change gears untill the gas is reapplied.

 

When I've got the car in DS, it will downshift and rev-match under hard braking. This is fine IMO. However periodically, when downshifting under braking, the car will lurch forward. I think that power is being applied to the transmission (just a little bit) even though my foot is nowhere near touching the gas pedal.

 

Is your car auto trans???? if it is, the car tries to use engine brake to help you get better braking to avoid any possible accidents.

 

^^ +1

its normal, also happens periodically when braking while going down a hill.

 

This is not normal, just had my TSB honored for this. Go to this site Infiniti G37 Technical Support Bullitins, scroll down and find the "2008 G37; INTERMITTENT/SHORT DURATION SMALL RPM INCREASE DURING BRAKING"...i think its the third one from the top. Print off the TSB and take it to the dealer and they will reset the ECU for you.