370z Dumping Fuel into Cylinder 2,4,6.. WHY??!?

Z34Life

Hi all,

we are mystified as to why my 370z is dumping fuel into the left bank (2,4,6) and then causing it to misfire. Short Term Fuel trim on Idle starts at about 10% and gradually over the space of 5 minutes climbs to 25% and then misfires, reset's back to 0% and then starts again ( 10 -14-10-12-16-14-20-22-20-24- 25). It's throwing the fault code p0300 and it also on two seperate occasions said misfire fault in cylinder 4 and then 2.


trying to figure out why it's doing this

What have we done so far

Via the TORQUE app we were able to monitor most things.

- O2 Sensors are fine
- Air Flow Sensors were swapped around and didn't make a change to the fuel trim dumping fuel
- We couldn't find any cracked or torn pipes.
- we ruled out coil packs as the code is across multiple cylinders and we know its dumping fuel so ignition is not going to cause it to dump further fuel.
- Timing is between 10 to 11 Degrees when idle.



Mods are

Stillen Gen3 Intakes
Titanium Amuse Exhaust ( After the Y pipe)
Berk High Flow Cats

All mods were installed 2 years ago, so its not like anything has been added new to the car since.


Any thoughts guys??