I have horrible gas mileage, like that of a Ford Expedition. 18 mpg on the highway, ~250 miles per tank. I can smell a faint gas smell under the hood while the engine is running. I wonder if bad injector(s) would cause this gas mileage to be this bad. And the fuel line is not leaking.

I have replaced/done the following:
PCV valve
Fuel Filter
Air Filter
Coolant Temperature Sensor
O2 Sensor
cleaned throttle body
cleaned MAF sensor
ran 2 tanks with Chevron with Techron fuel treatment.

I am in skeptics of what to do next. Fuel injectors, would they cause that bad of gas mileage?

 

check to make sure the lead on the 02 sensor is the same length as the origoinal one. longer length lead would change the resistance and could effect the fuel air mix. I had a gas leak in my 93 GXE, I could smell gas but could not locate a leak. until it got to very cold. Then I found the leak under the top plenum a short rubber hose conecting the 2 injector rails. the fuel would leak when the engine was cold and would expand as the engine got hot and leak less or seal temporarily, the fuel would evaporate so I could never find the darn leak. I fixed that and the 02 sensor lead length and I am getting an average of 22 1/2 MPG or 9.5 KPL, EH.

Hope that helps

 

Are you talking about the wire to the O2 sensor? I just looked at mine and there is like 3 feet of wire that is bundled up down by the sensor and the manifold. Are you sure this would make a difference, and how did you fix it? Did you just splice the wires or what?

 

Check your fuel injection hoses for leaks(ie.. where the rubber lines meet the hard lines) If you have a VG, you have rubber lines UNDER the intake manifold too. Fine times.

If you have a VE, you have no rubber lines under the manifold.

After the car has been off overnight, open the hood, start car and look for gas leaks along the rubber fuel line connections

*how many times have I typed this?*

 

Yea, the after market 02 sensor comes with that bulk length wire. If you go to Nissan the replacement comes with the wire the same length as the origional.

All I know is, as soon as I shortened mine I EMMEDIATELY got better milage. not after 2 or 3 tanks but EMMEDIATLY.

Get some "Heat Shrink BUT Connectors" from Canadian Tire,,,Oops or the American equivalent. Pretty cheap stuff.

Measure the actual distance you will need from the Thread-o-let in the exhaust system to the plug in from the sensor. Use a piece of string or something. Then remove the 02 sensor and make the splice with the but connectors. Be sure you don't make the leads to short!! ""Measure twice cut once"". You know how that can go "But I cut it twice and its still to short"

In my GXE it was about 18" mabey a little less.

Good Luck

 

Are you sure this is going to make a difference? I guess I just figure a wire is a wire no matter what the length, to a certain extent.

 

The wire length actually might make sense. Cause if you think about it, its going to take longer for a reading to go to the ECU with a longer wire as opposed to a short wire. I am going to cut and resolder mine hopefully next weekend. I did get 100 miles on 1/3 of a tank strictly on highway driving, which is a record for me. I replaced my temp sensor, cleaned throttle body and cleaned MAF sensor last week. Might have had something to do. In city, my car is horrible in fuel economy.