My G37s has recently started to bog down and run poorly. Acceleration is mediocre, and shifting of the automatic is poor at the lower speeds. At the same time, the brakes have gotten extremely touchy and hard to modulate. It really reminds me of how the car drove with the initial flash for the 7 speed where there was incredible engine braking and hard downshifts, but this time there are no hard downshifts on a regular basis. The car feels all crossed up. I'm strictly stock right now, so not sure what could have caused this. I'm still under warranty, so I can take it in, but was curious if there were any recommendations to try to sort it out before taking it in. I've already done the ECU reset from the DIY post, which appears to be the accelerator mapping function, and i've also done the DIY brake booster process, but still no progress. Would appreciate any suggestions since this one is a mystery to me.

 

Have you cleaned your throttle bodies?
That will clean out all the unburnt carbon.
Try having brake system flushed, if your brake fluid has been heated up to the boiling point,it has since you drive aggresive like I do, it has lost some of its ability.

Tb is a 15 min fix.
Having brake line flushed, any decent mechanic can do that.
Dealers never flush line unless you pay them otherwise they just bleed them.
Had to go back 4 times for the same front brakes, tech working on my car was a newbie.

 

I haven't cleaned the throttle bodies, but that's definitely worth a try since it's running so bad. I figured if the brake fluid was old, it just wouldn't work as well...what I have is hyper sensitive braking...very weird. Thanks for the input...

 

if its still under warranty i would just take it in...getting into the throttle bodies and everything sounds like too much. should never have to do that on any car with less than 150k miles or so.