Bring back from the dead with update. New brake switched seems to have resolved my lagging throttle and poor low end acceleration issues I've been dealing with since '09.
The shimmy added to the brake pedal helped with the brake switch contact 2 years ago, but it did not eliminate the hesitation and rough acceleration feeling as if the engine wasn't sure what to do.
So I convinced my dealer to install a new brake switch since I was told some Altima owners experienced similar issues. Plus, some users here complained about difficulty accelerating which felt like limp mode. The week prior, I was in a situation where all of a sudden the car lost power. I floored it in 1st and 2nd to redline, and it took awhile to get there. Plus, boost wasn't building up at all. With the pedal to the floor, it felt like the throttle was as barely 1/4th and wouldn't ramp up past 50% (enough to get the turbos to spool).
Anyhow, the car feels great for the past week. Acceleration is brisk and smooth. From tip in I can feel the car want to scoot, and as I slowly press down on the pedal power kept building up without hitting the wall. I'm also able to get the car moving fast from a stop when making a left turn.
So for everyone out there with such issues, try to convince your dealer to change out the brake switch. Vibration might cause some sort of intermittent behavior, or the signal out of the switch is wonky.
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