First Tank -10.8 MPG REALLY?

[disallow]

The best thing to do now is be vigilant. Monitor your FE over several tanks and see if you get the same results. I wouldn't advise taking a calcuation off of one tank, especially given the track record our pathys have with regards to the level sending units.

My 08 honda civic has a ridiculously huge top 1/2 of the tank. If you really work at it, you can get an extra 8-10 L of fuel in, which means that I can usually get 400-450km from 1/2 a tank. However, this is inadvisable, as I'm probably overfilling, which the manufacturers never recommend.

Once you have the data, the next step is diagnosis (provided the FE is still unacceptable). Start with easy stuff, plugs, seafoam, check for diagnostic codes. I have a superchips tuner that gives you a good look at the internal functioning of the engine, including engine load, and readings from the O2 sensors.

From there, you can look at replacing aged hardware on the engine. MAFs are known to go bad, as well as primary O2 sensors.

[Rapscallion]

The best thing to do now is be vigilant. Monitor your FE over several tanks and see if you get the same results. I wouldn't advise taking a calcuation off of one tank, especially given the track record our pathys have with regards to the level sending units.

Once you have the data, the next step is diagnosis (provided the FE is still unacceptable). Start with easy stuff, plugs, seafoam, check for diagnostic codes. I have a superchips tuner that gives you a good look at the internal functioning of the engine, including engine load, and readings from the O2 sensors.

From there, you can look at replacing aged hardware on the engine. MAFs are known to go bad, as well as primary O2 sensors.

Right now I am just going to get an average over the next few tanks after adding fuel system cleaner/injector cleaner, proper tire psi, air filter, etc (all the normal non-invasive type of items).

I highly doubt it is a problem with the MAF or O2s as there is ZERO performance issues, no hesitation, shaking, CEL, etc.

Thanks for the response.

[disallow]

I changed my primary O2s and had significant results. Highway cruising FE went up by around 30-40%. My truck is older and has higher miles than yours though...

See my posts here:

http://www.thenissanpath.com/viewtopic.php?p=35925

and:

http://www.thenissanpath.com/viewtopic.php?p=36049

[kelleyo]

Have you subtracted a % of the rated MPG for using Ethanol laced gasoline?


http://www.cleanmpg.com/forums/showthread.php?t=11342

[Rapscallion]

I changed my primary O2s and had significant results. Highway cruising FE went up by around 30-40%. My truck is older and has higher miles than yours though...

See my posts here:

http://www.thenissanpath.com/viewtopic.php?p=35925

and:

http://www.thenissanpath.com/viewtopic.php?p=36049

Did you show any CELs? What mileage did you have when you did the replacement of the O2s?

[disallow]

Have you subtracted a % of the rated MPG for using Ethanol laced gasoline?


http://www.cleanmpg.com/forums/showthread.php?t=11342

If you run high octane, there is no ethanol.

Gasoline has 6% more energy content than Gasohol. So a 6% drop, although significant, is only 1.2MPG if you average 20MPG on non-ethanol treated gas.

t

[disallow]

I changed my primary O2s and had significant results. Highway cruising FE went up by around 30-40%. My truck is older and has higher miles than yours though...

See my posts here:

http://www.thenissanpath.com/viewtopic.php?p=35925

and:

http://www.thenissanpath.com/viewtopic.php?p=36049

Did you show any CELs? What mileage did you have when you did the replacement of the O2s?

No CELs. Just really crappy mileage. I didn't think I had a performance issue, but after the change, the engine is much more responsive, and towing it was much much better.

Mileage before change was 225km on 40L of fuel, or 5.6km/L, or 13.2USMPG.

Mileage after change is 350km on 40L of fuel, or 8.75km/L, or 20.6USMPG.

44% improvement. The above data is for highway only, city mileage has improved as well.

[kelleyo]

Have you subtracted a % of the rated MPG for using Ethanol laced gasoline?


http://www.cleanmpg.com/forums/showthread.php?t=11342

If you run high octane, there is no ethanol.

Gasoline has 6% more energy content than Gasohol. So a 6% drop, although significant, is only 1.2MPG if you average 20MPG on non-ethanol treated gas.

t

? Around here all grades (87, 91, and 93 octane) have 10% ethanol.

[skinny2]

Around here all grades (87, 91, and 93 octane) have 10% ethanol.

And that's if you're lucky. I have a friend with classic cars and he tests fuel at times and has found upto 30% in some fuels.

[kelleyo]

Around here all grades (87, 91, and 93 octane) have 10% ethanol.

And that's if you're lucky. I have a friend with classic cars and he tests fuel at times and has found upto 30% in some fuels.

I have found several stations that sell Non-Ethanol gas. I always fill my boat there and my cars when convenient.

[disallow]

Have you subtracted a % of the rated MPG for using Ethanol laced gasoline?


http://www.cleanmpg.com/forums/showthread.php?t=11342

If you run high octane, there is no ethanol.

Gasoline has 6% more energy content than Gasohol. So a 6% drop, although significant, is only 1.2MPG if you average 20MPG on non-ethanol treated gas.

t

? Around here all grades (87, 91, and 93 octane) have 10% ethanol.

My bad. I should qualify that here in Canada, and everywhere else I have travelled to in the states (MN, ND, SD, MO, IL, WI) advertise that there is no ethanol in their premium fuel.

t

[Rapscallion]

UPDATE:

2nd tank averaged 12.9mpg so that's a 2.1mpg improvement from the first tank. Not great, but improvement nonetheless.

Not sure how much affect the couple of small things I did had (fuel system cleaner, Tire PSI to 38 from 32) but I'm still hoping to bring it up more to the 14-15mpg range.

Still plan to try a lighter weight oil in the future and possible add a K&N filter or CAI as well.

[skinny2]

That's about what i projected you would get compared to your previous cars. Given the AT tires...especially if they're new. I took a hit going to Michelins last year. I think the OEM tires are LRR or close to it. I wouldn't run thinner oil in Southern Cali...

[hfrez]

Very interesting thread. I have the 2011 SV and my millage is quite nice at 17.2MPG. Of course, we all live in different areas of the country and have different roads we travel at different styles of driving. But I must mention that in city traffic I have found by downshifting to 4th and not allowing it to go to 5th makes a big difference. This engine uses more gas when it’s in 5th gear at below 1000RPM. In fourth the vehicle responds much better in traffic and seems to get better millage.

Another thing I do is downshifting to use the engine as an engine break. Of course this is not possible in city traffic but on country roads and coming off of highway ramps it helps a lot. I can see the MPG jump up every time I do this and I'm not using the breaks as much. One of my biggest pet peeves is the waste of energy that is converted and lost when breaking.

Another thing I do, but I'm not sure if it really helps, is putting the transmission in to Neutral at traffic lights. It allows me to rest my foot a bit from the pressure of the break peddles and it seems to relieve the transmission from being disengaged at idle. When the light turns green I wait for the perfect moment (pending on how many cars are between me and the light) and I just pop it back into drive without using the breaks.