Hey all my girlfriends 2011 honda fit sport has an issue where it stutters and loses power a bit going around corners. We just changed all coil packs, spark plugs, cleaned the throttle, and injectors and put in a new air filter but it's still happening. Any ideas? Spark plugs were pretty nasty looking according to my mechanic.

 

It mostly happens when turning corners but can happen while driving regularly, it definitely seems peppier and the power loss is slightly less since adding new coil packs and plugs but the problem definitely persists

 

I'm never a fan of firing the parts cannon at the problem. A wise mechanic (let's be honest, one with more time) would have taken it for a drive with a data logger active. Introducing lateral loads under normal circumstances wouldn't affect power. I reckon a bad ground or fuel pump but a data logger would make a more accurate diagnosis.

 

Not saying that any of those electrical things didn't need changed (I would have only done the plugs and then do the coils packs if I got a code), but as noted, you still have some version of the same problem. Again, not saying that it isn't another unaddressed electrical problem but.....

If not electrical, could it be mechanical? Going around corners loads the tires, wheels (lug nuts), bearings, suspension differently. Do you hear any 'new' noises when cornering or going over bumps? The shuttering could be something binding up as the clearances change as loading changes left/right.

Continuing in the mechanical line of thinking, you didn't mention what transmission she has. An automatic transmission (AT), is 'busy' all of the time except at highway speeds. So, could the shuttering be related to the AT shifting up/down between gears? If AT, have you ever changed the fluid? Most people stick with the Honda DW-1 ATF but others use other products but seems to me that the costs aren't that different, so I stick with the Honda ATF on both an '09 CIVIC (130k miles) and '11 FIT Sport (80k miles). Others here routinely change their manual transmission (MT) fluid too.