My 1998 infiniti qx4 is misfiring on smog and the light was on

Question

My 1998 qx4 is misfiring while in smog with service engine soon lights on but when i put full tank of gasoline with shell with plus or supreme and chemtool additive or shell gasoline only the light of service engine soon suddenly turn off and when i consume the gasoline up to half of the tank the light went back, do you think the pressure of it are the ones affected and also do the cover tank cap of gasoline needed to replace, but how come only shell gasoline can turn off the service engine soon light? Not the other brand, Maybe there is something wrong only the pressure of the gasoline.

Answer 1

Hi there

This code is for multiple misfires. This is normally a problem with the spark plugs, plug wires or distributor. The high test fuel may be helping, but that would only indicate that you possibly have worn out spark plugs here. The fuel cap isn't going to help with this condition. Here is a list of the possible causes for this code

P0300 INFINITI - Cylinder Misfire Detected Random Cylinders

Read more: https://www.autocodes.com/p0300_infiniti.html

Comments

What is incorrect fuel pressure causing and  insufficient cylinder compression due to misfiring, and the only thing that my other mechanic since i smog it, he said wait 2 years to replace my suv before smog or do you think there is more way to fix this misfiring maybe my mechanic never pinpoint exactly the misfiring cause, caused my suv runs well only it misfire and causing failing for smog test but if the light reset it, it will pass the test.