Poor gas mileage ?

[tduval]

I recently replaced the MAF sensor and injector coil (Cylinder #5) on my 2000 Maxima. It runs well........but I have noticed a significant decline in miles per gallon.

Any thoughts on what could be causing this?

Any help appreciated.....

[jltibbs]

Welcome to NICO!

is your check engine light on, or are you just getting bad gas mileage? if your CEL is off, then i would look into changing the air filter, spark plugs, and cleaning out the throttle body with some throttle body cleaner.

[Double E]

If you're over 100K miles you're about due for the knock sensor to be replaced. IO was down to less than 300miles per tank when I figured it out. It will not throw a CEL code unless another emissions-related code is also present. Google it and also look at maxima.org for more info.

If you pull the codes, it might be there as a ghost code. PM me if you need add'l info on how to replace it. It's DIY but you'll need to get creative.

I would also recommend pulling the TB and cleaning it.

[ZGadson]

If you live in the same type of climate I do (in Northern Indiana), you're probably just getting low mileage because of the cold weather. Believe it or not, cars run best when its slightly humid, which makes for optimum gas mileage in the summer.

Zach

[lucasjsr]

The Maxima site has instructions for testing the KS it should measure 550K ohms + - 5%.

[edpapaj13]

I noticed a decline too for some time now, maybe a year or two. Last time I waited until it was under E and filled it up with 89. It lasted me for around 260miles, it was 80% city driving, and the heater barely on. I wasn't abusing the car, although i put a CAI i avoided flooring it just to get a better estimate. I'm replacing my ypipe with either a warpspeed or stillen. I heard that can help bring the numbers higher. Needless to say i averaged about 16mpg and it lasted me 4 days!!!

[tduval]

All good tips - thanks.

In the past 3 weeks, the weather in Fargo has been ranging from +5 deg F to -25 deg F. There were 2 days last week that managed highs temps around 30 deg F. Mileage was noticeably improved just in those 2 days.

Just kinda frutstrating that it performed better before changing the MAF and injector coil#5.

I need to wait for a warm up before I attempt much else as I do not have a heated shop/garage to work in.

[Mike G]

Don't quote me on this, but you could always stop by the dealership and have them re-flash the computer, for a few $$$. Seems that there is a window of opportunity where the MAF replacements may require that. Some get away with not needing it, some require it.

Just an additional thought... --Mike

[oilerftbll84]

All good tips - thanks.

In the past 3 weeks, the weather in Fargo has been ranging from +5 deg F to -25 deg F. There were 2 days last week that managed highs temps around 30 deg F. Mileage was noticeably improved just in those 2 days.

Just kinda frutstrating that it performed better before changing the MAF and injector coil#5.

I need to wait for a warm up before I attempt much else as I do not have a heated shop/garage to work in.

Dang thats cold. that could be the problem so wait till it warms up but if you see no difference then do as the other guys said.Good Luck