05 coupe AT 184k miles
cold air intake, aftermarket exhaust and/or cats (not sure what kind, they were on the car when i bought it)

trying to diagnose my p0300 code
only misfires from about 4500 rpm and up then it will make a sputtering sound and rpms drag slow and dont really increase upon full throttle (higher the rpm the worse it gets)

4k rpm and under it runs good tho, no bad sound, has good power

its the only code im getting and im using a bluetooth obd2 scanner with torque app

-ive done all the relearning procedures
-its not the spark plugs (no fouling or oil, and i swapped em and its no difference)
-correct gas, using 91
-no oil on coils or plugs, checked em all
-wiring is correct, everything is plugged in the correct spot
-cat, evap, and 02 monitors stay not ready.. not sure if that matters
-pulled the vct solenoids and checked em out (look good as new no blockage)
-i dont think its an air leak, intake pressure stays around 26 or so
-pcv valve checked out ok

some things i am suspecting it might be are: fuel injectors, fuel pump, fuel pressure, 02 sensors, cats, coils (doubt it tho bcuz its multiple misfire), cam sensors, crank sensor....

i doubt its a sensor bcuz i would think i would be getting another code on my obd2 scanner corresponding to a bad sensor or reading

anyone have suggestions or experience?
anyone have experience with the torque app and what numbers or readings i should be looking at?
could it possibly be bad cats or 02's even tho im only getting p0300?

thanks in advance. im determined to get this solved

 

Here's a link to the P0300 diagnosis. http://www.engine-codes.com/p0300_infiniti.html

Quoted from the info there:

"When is the code detected? The control module monitors the crankshaft speed and has detected a misfire condition Possible symptoms - Engine Light ON (or Service Engine Soon Warning Light) - Lack/loss of power - Hard start - Engine hesitation P0300 Infiniti Description When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position (CKP) sensor signal to vary, the Engine Control Module (ECM) can determine that a misfire is occurring.

Read more: http://www.engine-codes.com/p0300_infiniti.html"

So it could be a faulty crank sensor or I've also heard it pop up when one of your cats is bad. HTH

 

the same problem my car is throwing codes p0011 n p0300 it's bad to the point i dont know what to do it spudders n causing it to 2 step while I'm driving it already went into limp mode once