Hi,

Newb, here. I have a new to me 1996 I30. I am getting about 20MPG, I thought my gas mileage would be better. More like 25 MPG, since most of my driving is highway driving. Anyway, I have replaced an O2 sensor and have been told that my knock sensor is bad, per the ECU codes. Could the knock sensor cause me to be having this poor gas mileage. The car runs very smoothly right now.

TIA

Lisa

 

The KS will cause this, try reading the FAQ's very thoroughly

 

The FAQ's have a lot of good stuff, take a few minutes to read them.

There are so many things that can affect fuel economy though - almost anything regarding the car's condition can change this. Are your tires under/overinflated? Is your suspension properly aligned? Do you use cruise control on the highway? How many miles has it been since your spark plugs have been changed? since your fuel filter was changed? since your air filter was changed? Are you using fuel with a low (less than Premium 93) Octane rating? Also, try running some STP fuel injector cleaner fuel additive when you fill up next time. Just a few thoughts to get you started...good luck!

 

Nissan does not recommend fuel additives.

 

no company recommends them but that doesnt mean there not good to use every so often

 

I use STP every oil change (5,000) and it has not done any harm what so ever.

 

i have the same problem...getting 18 mpg changed the spark plugs, air filter, fuel filter, knock sensor, used STP a few times, tires are properly inflated... the only thing is that rear o2 sensor code came up for one day, then just went away... and i am getting code 0505 which means there are no codes at this time...

also i heard that when you are replacing spark plugs, you need to adjust them somehow? I did it my self, and didn't adjust anything, could that be a problem?

what else is causing low mpg?

 

well i guess I get around 21~23 mpg but it's like 60% city driving. The specs for 98 I30 says that the mileage is 21/28 in city/hwy and so i was expecting around 24~25 on 50/50 city/hwy but seems like my car is getting old (~7 yrs!) and hence the drop.

 

Haha, I get 9 miles to the gallon haha ...

 

I thought my 17-ish was bad. I went down to a little below 17mpg for a while, and when I changed my brakes I discovered they were sticking. Now I can hit 19-20 mpg (with a good amount of city driving). Not great, but I am happy I can hit over 300 miles a tank now (about 325 or so, it was a little over 280 before).

 

those things you buy over the counter are a waste of money that dont do anything. Go to a dealership and get a real bg flush or sun flush

 

i get 13mpg, and its not fixable since ive tryed everything

 

Well I personally blame my fmu and fuel pump !

 

I get abt 330 to 350 miles a tank (I mean for abt 16 to 16.5 gallons). I gotta change fuel filter, get new spark plugs as well. Maybe I'll drop in a K&N sometime next year.