Nissan Repair Questions? Ask a Mechanic for Answers ASAP
Hello, my name is***** you tell me if it is only the 300 code that you are getting or are there others?
Thank you. If the engine has been tuned up and it did not take care of the issue then I would clean out the air flow meter and check the fuel pressure. It may be a weak fuel pump. It can also be deposits on the intake and the injectors so if the issue is subtle you should run some seafoam through the intake to see if it will clean up and run better.
You will need a fuel pressure gauge with the correct fuel pressure adapter for the fuel line. Do you have access to one?
Does it show the fuel trim readings for long term and short term?
The one that bounce back and forth to 25 makes me suspect low fuel pressure. Would you be able to test the pressure? It should be around 50 psi.