Exhaust leak maybe?

Driving habits also make a big difference...do you drive agressively?

 

I know that our cars are not going to get outstanding mileage but anything below 15 MPG in "normal" driving seems awfully low. I average 19 from month to month with a mix of driving, city and highway, and a mix of style - ***** out on occasion and a bit spirited most of the time. I got 28 on the highway yesterday over 260 miles, cruise set at 70-75 most of the time. I don't fault the OP for his post - I think he has a problem somewhere.....

 

just curious. how much is the gas up there in Vancouver OP?

 

These threads always just amaze me! I have an 03 with nearly 75k on it, and I get mid to high 20's! In fact if I drive 60 mph which I hardly ever do, but I have tested it just for curiosity's sake, and I get very low 30's.

I also know as soon as you turn on the mpg it will always be higher, so I always wait a few miles until it completely settles to get the correct reading.

Oh and op you do probably need a retune, and check your o2 sensor. Those stretched tires of yours is also dropping you a couple mpg is my guess. Tire pressure is also a big deal.

 

My daily commutes get me 19 MPG with "normal" driving with an occasional heavy foot sequence.

I drive to Monterey every year from Los Angeles, and average between 28 and 30 MPG. Just set the cruise control at 3,100 RPM and cruise it.

Car is FI and a 6MT. before the FI I could get nearly 33 MPG on a good cruise without traffic.

 

O2s were checked by nissan, and im planning on getting an osiris. And yes i realized the tire situation is not helping. I will be putting on a set of wider tires in the spring.

I fill up at $1.38 a litre (94 octane)
If i did my calculations right thats $5.26 a gallon...

i agree, there has to be a problem somewhere, and it may turn out to be something so small that its gonna be real hard to find.

I do from time to time. But when i tested the gas mileage, i did not drive aggressively at all.

Those numbers surprised me lol. Damn inefficient gov't regulations! haha Thanks for the info.

Injectors are going to be cleaned as soon as spring comes around and the car comes out of the garage, thanks.

Yes, im thinking of getting an osirs tune done, with a fuel map specifically designed for what i use. And if i play with mine..id estimate about 11mpg

My 02s are running fine, i had one replaced recently (checked by nissan)
No siezed calipers or brake drag
Transmission fluid was changed with the nissan one about 3000kms ago. (same mpg before and after change)
Fuel injector cleaner - i was gonna use seafoam
The diff oil.. i dont know if that has ever been changed on the car, i will look into that. Thanks.

My average mph would be.. im not sure. i never checked. But speed limits are 50km/h so id say the most i normally go at is about 60km-65 km/h.

Gas mileage was never a top priority, and never was it stated as such, having the car in proper working order is the top priority. Thanks for the well wishes.

 

i think the gauge closest to driver should have an option for mpg and underneath that it says mph. at least it does on mine and i have an 03 perf...

i got like high 20s low 30s mpg when my avg mph was in the 40s-50s.
when my avg mph dropped down to 20s (indicates more local driving) my mpg dropped to low 20s high teens.

imo mph is pretty good for getting an idea (i think its over time, not distance since mine drops when i idle >> distance constant but time increasing) of what youre doing

gluck

 

Manual transmission, cruise control @ 70, premium gasoline only, and completely stock. I've gotten over 30mpg on the highway, but it usually levels out at 24-27mpg overall (city and highway). I'm guessing it's those mods that kill you mpg.

 

The mods are actually supposed to increase your mpg, but in reality when you have more power you tend to use it, so realistically your correct. But when i was testing my mpg i was easy on the gas.

 

I'd change the other O2, you never know it could be going bad but it's still putting a signal out. Check and double check everything. Is your car reaching proper operating temp? A faulty thermostat could keep things running rich. Follow down the line starting at the maf and ending to the fuel injectors. Make sure your spark plugs aren't fouled. Check the ignition system, fuel injection and emissions system.

 

I am really surprised at some of your claims you all receive.
I have an 07 HR with 18k miles. Mobile 1 5w30 changed every 2k miles. 6 spd. I do play with it in town getting on it, no doubt about that. and deff while getting on the highway. Ive not see high 20's or low 30s for quite some time because all i do is play in it when it gets out. But even around town and highway, half/half i get 21 lowest. but then again im not driving around in 1st all the time too. i do shift after the acceleration and play time.

 

I have an 03 with almost 75k 6spd. I use castrol full synthetic 5w30, which I change every 4k miles. I also have a cold air intake. I get around 22-25 city and 29-31 hwy. I'm putting exhaust on Monday! I'm hoping it may give me a couple extra, but it also may make it a bit worse. I guess I'll just wait and see what happens.

 

yea same here i have gotten 41 mpg going 70 highway, but city i mostly get around 16 if my average mph is like 15-20, and my car is completely stock

 

After i had removed my cats, my car threw a CEL, so i went to nissan and they cleared it for me, but the tech said it was my o2 sensor bank 1 sensor 1, the one thats in the header, and that even if they cleared it, it would come back. Which it did. So i changed that 02 And then i took it back to clear the light, which they did and it never came back on. I dont remember the exact error code but i remember it said i was running lean not rich.

The car gets to proper operating temp, atleast thats what my gauge is telling me.

Fuel injectors will be cleaned in spring, when i take the car out of storage. In the meantime ill check the sparkplugs.

Im a bit scared to touch the MAF, i heard they break easily and cost a lot to replace.

And what do you mean by ignition system and emissions? Could you be a bit more specific please.

 

I didn't know that. A friend at work said the same thing not long after I made that post.

At least I have better mileage to look forward to.

 

Haha, yeah its pretty surprising, but you only get better mileage if you drive like grandma! So..dont count on it. haha.

 

I have an 08, bone stock I was averaging 22-24 mpg.

Since 19" rims, intakes, exhaust, hfc, fuel remap I'm getting 19 mpg.

Then after 4.083 gearing, Quaife I'm getting 17.

 

Simply put, I'd check all the connections to the spark plugs and the plugs themselves. If you're positive it's not the O2 sensors then leave them be. Somehow I don't trust exactly what the dealer did to yours. If I had spare time I'd personally climb underneath and dismantle, clean, inspect/replace all the O2 sensors. But that's just me. They could be sending a signal out, but not tripping the CEL.

As far as the ignition system goes, there's not much the DIYer can do except to inspect and the plugs and make sure there's no oil coming up the spark plug tubes, fouling the plugs and hampering the conduction. Make sure there's nothing wrong with each coilpack.

Here's some other random stuff: Make sure your air filter isn't clogged or dirty. Make sure your tires are properly inflated, check. Brakes are not binding, checked previously, right? Inspect for fuel leakage. Check all the connections, lines and all the components in the fuel system. Inspect your fuel injectors. Make sure your thermostat is properly working and not stuck open. Make sure your manual transmission is running the proper 75W-85 GL4 oil and the rear diff is 80W-90 GL5. Make sure your motor oil is at least 5W or 0W-30.

 

Just curious, are you guys getting your MPG from the screen built in the 350z? I'm getting pretty low mileage driving in the city, 14-15mpg. Does having test pipes have anything with low mpg? It's not like I drive aggressively either.. I'm close to 45k, which is time for a transmission/differential oil change also. VQDriver, did you get any results from the redline system cleaner?

 

I used to use it on my old maxima so I decided to try it out last month because the car was idling a tad rough and I was seeing low 19mpg on my nav. I blame crappy ethanol blend winter gas! The car started driving more smooth that same tank and mileage is back up to 19.5-19.7 despite WOT every other commute (damn holiday/weekend drivers) lol.