GoMaxVroom

Hi,

I was averaging 20-21 (90/10 highway to city) for my 200 Nissan Maxima- 5 speed. Have 4 new tires with proper inflation. I'm not an aggressive driver.

I went to a Nissan dealer to get my fuel injectors flushed, throttle chamber service, new air filter and transmission fluid changed.

That's when the problem started!!

After I left, I filled up with a full tank of Plus gas and drove for about 1 hour on the highway. Immediately, I noticed I wasn't getting the mileage boost I was expecting. In fact, I was getting 2-3 miles "less" per gallon, which really ticked me off after spending $280!! I was hoping for 25-28mpg, instead I was getting 17-19 mpg highway. My father's V8 - 15 year old Ford station wagon gets 19 mpg highway!!

I appreciate any ideas on why this is happening and how to fix it.

I assume the dealer incorrectly reset (messed up), some setting, valve, hose etc... These "mistakes(s)" more than offset any benefit from the fuel injector cleaning which is inexcusable, but I have no evidence besides crappy gas mileage.

What is a normal range for highway driving and mixed driving (city/highway)?

Thanks in advance!!

Spence

CCx

iTrader: (2)

my friend.... I've had a 2000 Max for almost 8 months now....extreme heat, extreme cold, etc. never had more than 21.5 MPG...after different tire pressures, some BG44k, never any gas except 93 or 94 octane, mobil 1 oil changes, etc...never, ever,ever over 21.5MPG except on a 700 mi. roadtrip got 22.4MPG....never been able to figure it out, and i've learned to just suck it up and live with it, which is unfortunate....but it is what it is as for driving, it's probably 70/30 city-type/highway

GoMaxVroom

Thanks for your response!

Why is this so? I was in the dealer's lot last week looking at the 2k4 models.
Looking at the sticker they had a range of 23-33mpg highway with an average of 28 mpg. Now I understand the 33mpg is in optimum driving conditions, but that model also has a bigger engine - 265HP. Has Nissan fined tuned the engine that much so it gets 7-8 mpg on average? That's almost a 33% improvement.

Surely, there has to be a way to fine tune the engine to eek out another 1-2 mpg.

NYCe MaXiMa

iTrader: (9)

i've been getting crappy milage lately too
and it was abrupt.. one tank it was good, the next it sucked

seems like everyone gas milage in the northeast has crapped out becuse of the new gasoline they use now..

DAVE Sz

iTrader: (2)

You're basing all this after driving on the highway for just an hour? Get real. Wait a few weeks or a few fill-ups before you start having panic attacks. It's normal to see this stuff after engine services. Also that comment about the 2k4 maxima, that is should have worse fuel economy cause the engine has bigger displacement, just stupid.

GoMaxVroom

So how long should I wait until I see some positive effects? I would think if you flush the fuel injection system you would notice an immediate positive impact. I agree that a bigger engine would perform worse than this car. I guess this is false advertising.

What range should I be getting on the highway in the winter for a 5 speed?

Thanks.

spirilis

iTrader: (2)

Keep in mind, it could take days for your ECU to properly adjust to changes in the fuel or induction system...
I used to get an average of 25mpg during the summer, now I usually average 23-24mpg in my 2000... I assume it's just the weather, and more importantly, the changing fuel formulas.

Cutler

iTrader: (3)

OK, Spirilis usually isn't too smart but on this case he hit it just right. You had the flushing done, good choice. Why didn't they change your fuel filter as well? Also the gas mixtures in winter make for lousy gas mileage as earlier stated. So in conclusion:
-Get new OEM fuel filter
-Few days for ECU to relearn
-Mileage gets better when warmer




Vote Al Sharpton in 2k4

Colonel

Because Nissan BELIEVES WHOLEHEARTEDLY that their filter will last 100K and is a "non-servicable" item. Whoever heard of a filter lasting that long? In almost ANY car I have read a manual to, FF is replaced around 30-50K...so what makes Nissan any better...surely they dont have some new fangled technology that allows...oh wait...its in the gas tank. Thats why. DumbAss Design.

I also was chasing a fuel mileage problem at 29K or so miles. I ended up replacing the FF and that did the trick. My FF was NASTY and the fuel in it was gel like from all the debris.

I did it myself, and while not hard, there are a few tricks to it. Depends on if you are a DIY kinda person.

Good Luck!

Cutler

iTrader: (3)

I totally forgot about the placement of that filter on 5th gens, I had the SER on the brain. Regardless 100k for FF, don't think so. Good call on saying it can be done. I would have tried it.

GoMaxVroom

I new to these abbreviations.
What's a ECU? Is this a computer?

And since the fuel filter in the fuel pump, how will anybody know when it has to be replaced? Is replacing the whole FF a good thing to do after 40k, 80k??? Are we talking about 1-2 mpg difference if done?

I spoke with the dealer today. Part of the drop in the mpg was an O-ring out of place or something like that. My mechanic said the flushing may have jolted it loose disrupting the fuel line to the injectors. Seem plausible, but is it a lot of hooey?!

Thanks.

Raf2kMax

iTrader: (2)

woww..ive been getting REALLY bad gas mileage for about 5,000 miles now probably..2000 max is prolly at only like 35,000 miles..replacing the fuel filter is a good idea good posts guys

Colonel

ECU = Electronic Control Unit (I think)

As for the FF, you really dont know if it needs replaced. I would replace it at the same interval you would any other car. The FF is NOT that special. The placement is stupid and lousy and I think its a brain fart of a design. When I did it I got 2-3+ MPG back..I was really hurtin. But the service center said emphatically that it did not need replaced.

As for the fuel line story...seems plausible...but if that really did happen, I would suspect a tech that did you system incorrectly.