Grill Guard Nissan Xterra

How to improve gas mileage in my 2001 Nissan Xterra 4×4 V6?
Any suggestions on how to improve my diet fuel? i the Last summer was 18 to 19 mpg. Now I have an average of 14 to 15. Nothing has changed on the outside to cause this (ie, large tires, a grid), I changed the oil regularly, I just changed the fuel filter, air filter, spark plugs lighting, son, rotor and cap. My tire pressure is good. I tried STP fuel injector cleaner Autozone (which he said is guaranteed to increase the miles .. Not at all!) I sold this thing called Lucus fuel injector cleaner, not sure if it's worth a try or not … I have not noticed a big difference if I have the baby while driving. She sucks the same amount of gas. Any suggestions what could I do to return to 18 of 19 miles per gallon?
Robert M Cleaning mention IAC, IAC has nothing to do with fuel economy? IAC is idle air or solenoid control valve. Its main objective is to regulate the engine idling speed, but it has absolutely nothing to do with highway driving and fuel saving period. Now for the engine oil, Nissan used engine oil from the first regular day, I mean showroom fresh, the day that someone will buy your car and leave. You were getting 18 to 19 MPG last year, so the oil it that has nothing to do with the sudden great loss MPG? My suggestion is to take your vehicle technical experience and explain your concerns. Yes, you may not I like the idea, but please read on. They diagnose your vehicle through the scanner is little chance that it can easily cause bad economy fuel. 1 … Lazy oxygen sensor reading. Normally, oxygen sensors range from 0.10 to 0.90 volts volts quickly. oxygen sensor lazy bed too slow, you can kill your mpg 2. … Partially clogged catalytic converter. Yes, you read right, a semi clogged converter, which can gradually restrict your exhaust system. Your engine can not breathe freely as it used to be. Can be diagnosed in the scanner reading the chat monitors [another name for oxygen is back sensors] and comparing the readings of oxygen sensors front and rear oxygen sensors. 3 … crank sensor and cam shaft sensor, once again, vary the readings can give false computer records. Barometric 4 … MAF sensor new experience …. Technical and sensor to know the differences. You can say, "My Check Engine Light" is not activated and my sensors are in good working condition, unfortunately, which is incorrect. If the sensor is within certain parameters, the computer will not do "Check Engine Light" on. Only experienced technicians know what is happening on the monitor through various sensors of the scanner. You can find something that is not kosher. Example … oxygen sensor lazy sometimes to read between 0.6 volts to 0.9 volts instead of 0.1 to 0.9 volts. A technician then find out why your oxygen sensor is fluctuating high pressure side, technical verification from other sources such as vacuum leaks, pump pressure, timing and other things. If all is well, then you probe just the lazy Oxygen …. high .. there goes the mpg. One last thing stop using much fuel injector cleaning, you will do more harm than good.