Ok my friend has a 98 maxima and it gives him about 12.5 mpg. Were in the process of taking care of that.

Well when ever i goto the gas station i fill up 94 octane(highest we can get around here) So he gets 93. But my car is turbochaged dsm and im boosting high so it can knock and thats why i get the higher octane but with a maxima i dont think running 93 is necceray with 10:1 compression. and the thing is you get knock at wot he just does city driving he barely floores it and when he does it because im making fun of how slow he drives.

What do you guys think? but the thing is i have talked to people on the west cost they run like 91 i think because thats the highest they could find so im sure it would not give any negative effects on it right?

 

So his engine's knocking a lot more than it should, and he's getting poor fuel economy, right?
FYI, I do run 93 in my 2k, not sure what the compression ratio on the VQ30DE-K is though... but even when I ran 87 or 89 one time, I wasn't getting extremely poor fuel economy, maybe 1-2mpg lower than normal.

 

He might need to replace his fuel filter or knock sensor. Those can cause bad gas mileage

 

The owners manual states that he should run at least 91 octane.

 

Will a bad knock sensor through a code?

 

no, not unless you check for it...

 

yea, we run that because we CANT get better. the higher octane seems to help my gas mileage and helps with all those infamous knock sensor problems. have you change your KS recently or got the car serviced?