04 AWD Fx35 LOW MPG

H

husam96

Member
Hello, my dad got a 04 FX35 a few months ago, and the mpg has been really bad..

He drives 6 miles to work and back everyday and the computer is showing 12 mpg most of the time.. Now as it started snowing, he's getting 9 mpg!!

He changed the spark plugs, checked air filter, and still no improvement...

Is there anything i can do or is it this low because of his daily commute?
//Driving 55 miles an hour on the highway shows around 20 mpg

Tire pressure is good, all season tires 18"

Any hope? It's quite the change coming from a car that does 25 mpg city..
 
If it's 6 miles of nothing but stop and go driving then that might be right. I have an 07 35 and get about 24 hwy and 15 city.
 
The 55 MPH on the freeway seems a bit low which would lead me to believe there may be an issue all around with fuel consumption. Has he cleaned out the fuel system?
 
husam96 said:
Hello, my dad got a 04 FX35 a few months ago, and the mpg has been really bad..

He drives 6 miles to work and back everyday and the computer is showing 12 mpg most of the time.. Now as it started snowing, he's getting 9 mpg!!

He changed the spark plugs, checked air filter, and still no improvement...

Is there anything i can do or is it this low because of his daily commute?
//Driving 55 miles an hour on the highway shows around 20 mpg

Tire pressure is good, all season tires 18"

Any hope? It's quite the change coming from a car that does 25 mpg city..
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While it is most definetly on the low end of the mileage spectrum. it is not unusual mileage.

The FX's (and all infiniti models for that matter) have a higher emphasis on performance rather than economy. Gas mileage is not exactly pretty for these things.

---------- Post added at 10:40 PM ---------- Previous post was at 10:35 PM ----------

Maybe the other guys are right, check the rails, and some of the other fuel systems. I guess I didn't think it was so bad because I drive with a heavy foot, so my mileage is terrible.
 
He didn't do anything to the fueling system.. A friend of his also had a FX35 and he sold it because of the low mpg.. Yet when i asked him how bad it was, he said he was getting 17 mpg!

Also forgot to say that it has around 95K miles. Changed oil with Mobile 1 5W30 synthetic a month ago.

Run 93 octane fuel from random stations.


So how would i go on checking the fueling system? I have a OBD2 reader in case i can use that to monitor sensors or something..
 
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Based on my driving patterns, I would see optimum mpg on speeds between 60-70 which would get me 22 highway and 17-19 city. But I have a heavy foot :-(


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---------- Post added at 03:42 AM ---------- Previous post was at 03:41 AM ----------

While I was still in NY I average 12-15mpg



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Reset the ecu by disconnecting the battery for a little bit. Same thing happened to my 07 when I changed my plugs: fuel economy went to crap.
 
STIBungy said:
Reset the ecu by disconnecting the battery for a little bit. Same thing happened to my 07 when I changed my plugs: fuel economy went to crap.
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+1. I recently changed my spark plugs and the mpg was horrible for like a week. So I decided to disconnect the battery overnight and everything came back to normal. I live in Canada so right now my mpg is 13.8L/100km and it's a good mpg. Before the battery reset it was 17L/100km
 
I get about 19-20 doing avg of 80mph...city is bad 12, in I'm luck 13.

I did notice a bit of an increase on mpg when I used the injector cleaner for my other cars with higher mileage.
 
I just disconnected the battery. As of now it's getting 10.2 MPG and reading 158 miles till empty..

Will reconnect tomorrow or when ever i'm going for a drive again.. and drive normally, and will post mpg then..


Hopefully it works! thanks for the recommendation

Also, my dad bought these costco matts that block the accelerator from going WOT -.-! I think it can barely go 60% in :(

good for MPG i guess
 
Unfortunately, the mpg hasn't changed much.. 8 MPG for 5 mile round trip with snow mode on.. I know snow mode kills mpg but it was my dad driving..

Will try to go somewhere today and drive on normal mode.
 
If it's stop and go w/ lots of idling, you're not that far out of the ordinary. I commute ~8 mi. each way and I live in the city, so no highways, all surface streets. I average 12.2 mpg (measured by fillups, not the computer). The FX just has terrible fuel economy and the AWD doesn't help. The 5 spd. auto is a drag as well, notice newer FX's with the 7 spd. have better economy even with more power. On road trips of all highway, the best I've ever gotten was ~19 mpg at 80 mph average. Nothing has really changed my average economy, none of the mods did anything, none of the usual maintenance has done anything, reset the ECU does nothing. It's really because the FX is heavy and slightly underpowered so the engine has to work relatively harder than a lighter car with more powerful engine. If you ever look at your bar chart showing current mpg on the highway, just to maintain speed on a tiny hill, the bar drops below 10mpg immediately then goes back up. On my old Lexus IS350, the bar wouldn't even budge on small hills to maintain speed. Lighter car, more power. Same with my 335i, probably 120 whp over the FX, about 600 less lbs, and about 5mpg better in the city and 9 mpg better on hwy.

---------- Post added at 10:29 AM ---------- Previous post was at 10:20 AM ----------

I don't think snow mode would effect anything? It really just limits rapid throttle inputs which actually should help fuel economy, it's those quick throttle inputs that lower economy, so smooth should be better. It does go 50/50 on the AWD, but kicks out at 12mph so economy impact should be minimal.
husam96 said:
Unfortunately, the mpg hasn't changed much.. 8 MPG for 5 mile round trip with snow mode on.. I know snow mode kills mpg but it was my dad driving..

Will try to go somewhere today and drive on normal mode.
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I wouldn't rely too much on the car computer. Best to calculate mileage by hand. Car computer can be off, especially if you're just driving short distances.
 
i use to get 15mpg city i was happy now it drinks up gas just like my m3 12mpg city. I recently cleaned my fujita air intake filter it helped for a while but now its down again. I havent had time to install the front plastic undertrays, having a shortram intake is not helping at all. The filter got thirty in matter of days. Next up is spark plugs i havent changed them
ever on my ride. I do mostly city stop and go traffic commute. Hopefully i can get it back to 15mpg having rwd
 
My brother had a G sedan until last month. He lives down the street from me and in all city driving, he'd average 18 mpg. That basically tells me that the engine just works so much harder in the FX than a G. It's like the episode of Top Gear where they had an M3 chasing a Prius around the track and the M3 got better mileage because the Prius had to work so hard to get around while the M3 was cruising. My friend's X5M gets about 11-12mpg in the city even though it weighs almost 1000lbs more. But it has 555hp so he's basically barely on the throttle in the city.
 
pmanliu said:
I wouldn't rely too much on the car computer. Best to calculate mileage by hand. Car computer can be off, especially if you're just driving short distances.
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^:plus1: My screen display 28 mpg. In reality (manual calculation) I gets 17 mpg with 80% highway. Stop and go traffic has major impact on the mpg displayed.
 
shadow191 said:
My brother had a G sedan until last month. He lives down the street from me and in all city driving, he'd average 18 mpg. That basically tells me that the engine just works so much harder in the FX than a G. It's like the episode of Top Gear where they had an M3 chasing a Prius around the track and the M3 got better mileage because the Prius had to work so hard to get around while the M3 was cruising. My friend's X5M gets about 11-12mpg in the city even though it weighs almost 1000lbs more. But it has 555hp so he's basically barely on the throttle in the city.
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My gsedan gets about 16-17 mpg before my tune. After my tune I'm 18-19.

My display normally says 16.

Still sucks compared to many newer cars that make similar power.

Sent from my SGH-I337
 
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