Bad Fuel Economy - Continued...

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disallow
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Postby disallow » Sat Aug 13, 2011 8:52 pm

Well, after a couple tanks, its pretty conclusive. Changing my O2 sensors had a 20-30% improving effect on fuel economy.

I read the voltages and trim values again. Seems there are still some anomalous readings, so I wonder what is going on in Bank #2, but I now am back to getting 350km on 1/2 a tank (confirmed 39L fill) from 215-240km on the same amount of fuel before the sensors were changed.

Based on the improvement, and our average usage of fuel per month, this repair should pay for itself in about 3-4 months.

Yay! :)

t


Npath
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Postby Npath » Sat Aug 13, 2011 10:26 pm

disallow wrote:Well, after a couple tanks, its pretty conclusive. Changing my O2 sensors had a 20-30% improving effect on fuel economy.

I read the voltages and trim values again. Seems there are still some anomalous readings, so I wonder what is going on in Bank #2, but I now am back to getting 350km on 1/2 a tank (confirmed 39L fill) from 215-240km on the same amount of fuel before the sensors were changed.

Based on the improvement, and our average usage of fuel per month, this repair should pay for itself in about 3-4 months.

Yay! :)

t
I may have missed it but what brand O2 sensors did you get? Denso, Bosche...?

What of NGK?

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disallow
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Postby disallow » Sun Aug 14, 2011 3:03 am

Ended up with Denso, bought from Rockauto for $86 each.

patrickm
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help related to this thread

Postby patrickm » Sun Aug 28, 2016 2:31 pm

I've also been getting about 11-12 mpg around town (US gallons) for the past month or two. tried running w/o the a/c, there was some improvement, but over the winter with the same driving routes and the winter blend gas i was 14-15. (on the highway i'm still getting 20-21 with the a/c on full time, so that's fairly similar). but i seemed to get better mileage in short test drives in open loop mode than closed.

i have no codes, but have been watching the A/F sensors (upstream oxygen sensors), using the Torque app, and noticed occasional slow/erratic response, and that all but one of the sensors (B1S1) were reading in the 0.9v range, with B1S1 in the .4-.6v range, which i thought was normal for the front sensors. After a swap while doing my brakes, i seem to have a bit better acceleration, and it's too early to tell mileage changes, but i still have similar ranges in torque. I know there are issues with how those OBD-2 readers report certain signals for certain brands of vehicles, so could someone confirm on their pathfinder (who also isn't getting 12mpg city) that these levels are normal in torque?

i'd post a picture, but the board does't seem to let me. I will say that the two sensors i pulled looked different from each other, and one had some discoloration probably from heat. One looked similar to the Denso's i put in, but the other had a different shield around the sensor element.

for LTFT's, one bank around town is about +3%, the other is about -0.8%. on the highway, they can get to as much as 6.2% and -1.6% for long, steady drives.

i swapped out the PCV, and most of the crappy looking hoses. i compared it to my brother's 2011 a few weeks back, and it was pulling similar vacuum at idle and 2000 rpm. (he doesn't have the scan tool or live nearby, so i can't check his o2's)

any thoughts on what may be the source of the sudden drop in mileage, verification of what working AF's look like on torque, or ideas what else i can/should test would be appreciated.

Netdewt
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Postby Netdewt » Tue Dec 13, 2016 7:36 am

I just bought an 08. I'm getting about 12 via the computer on city streets. 30 mph max speed. I don't think it's that far off, I only hope it is higher on longer trips. I'm coming from a diesel VW so it's a bit of a shock.

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bhull3
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Drop in mpg

Postby bhull3 » Thu Dec 15, 2016 9:17 am

I've only had my Pathfinder since July and had been getting an average 18 consistently. Since the weather has gotten colder, it dropped to a low of 14. I run premium all the time. Did notice tire pressure went down on all wheels. Topped them off at 35 psi and now it's back up to 17 mpg average. Don't know if the blends have changed, but I figure it has to do with the cold and engine warm-up.

the ocho
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Postby the ocho » Mon Nov 20, 2017 12:24 pm

bring back an old thread in hopes of getting some info.


I'm seeing my bank 1 O2 sensors at .5 to .6v (precat) and the bank 2 precat at .2 to .3v

it seems like my bank 2 precat is reading off - that's a really lean measurement if it's accurate. does anyone know what their precat voltages are averaging (at 1500 RPM)?

BullDozer
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Postby BullDozer » Mon Jan 01, 2018 11:14 am

I Also want to check my O2 sensors. I got an error code for the 02 sensor behind the cat but I cleared the code and the code never came back.

In city, According to avg mpg computer, I am averaging around 9 to 10 mpg in winter. In summer was around 11 to 12 mpg.
On highway, I can get close to 15 in winter, 17.5 in summer.

That is with light foot driving.
I can’t believe some of the numbers with people saying the get around 18 mpg in city. Wow. Wish I could get that. Maybe time to change O2 sensors?

All original O2 sensors on 2006 with 146k miles.

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smj999smj
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Postby smj999smj » Mon Jan 01, 2018 12:43 pm

I have a 2006 LE which I keep in AUTO mode all the time and the stock-sized 265/65R17 all-season tires. Most of my driving is highway and paved secondary roads and I also use cruise control as much as possible, usually set somewhere between 65-70 MPH. My summer combined mpg is 17.5 and winter combined is 16.5; on a long, interstate or freeway run, I'll see 20.5 mpg. Currently running a Superchips 87 octane performance tune.

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Postby Spatula » Mon Jan 06, 2020 7:21 pm

I am also getting about 14mpg (16.7L/100km) currently in my 2012 V6. I just bought her before Christmas and was getting about 12mpg (19.7L/100km) but changed the engine air filter and saw some improvement. She has about 87,000 miles (140,000km) on the odometre, and I'm considering getting the O2 sensors and plugs replaced. The Denso (2349036) O2 sensors are $143.77cdn on Rockauto.com. There are several other less expensive options, like Walker Products and API for around $30/each. Had anybody tried these sensors?

The dealer here quoted me 1.5 hours for the O2 sensors, and 3 hours to change the plugs! Is this normal? (They also quoted me $401.36 per sensor and $37.82/plug).

And how do I post pictures? Do I need a minimum number of posts first?

Thanks!

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disallow
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Postby disallow » Mon Jan 06, 2020 7:35 pm

Spatula wrote:The dealer here quoted me 1.5 hours for the O2 sensors, and 3 hours to change the plugs! Is this normal? (They also quoted me $401.36 per sensor and $37.82/plug).

And how do I post pictures? Do I need a minimum number of posts first?

Thanks!
You have to use an image hosting service like imagebb.

Good old Canadian dealer pricing. Buy the ntk sensors from clubplug.ca and the 93759 plugs as well. Cheapest Canadian source I've found.

Spatula
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Postby Spatula » Mon Jan 06, 2020 8:24 pm

You have to use an image hosting service like imagebb.

Good old Canadian dealer pricing. Buy the ntk sensors from clubplug.ca and the 93759 plugs as well. Cheapest Canadian source I've found.
Thanks Terry!
Image[/img]

TooMuchControl
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Places to purchase parts online in Canada

Postby TooMuchControl » Tue Apr 28, 2020 5:02 pm

First post here, and thought I could add places to buy parts with free shipping in Canada when ordering more than $100.

For certain items, they come within a few dollars or RockAuto (the best overall place to buy so far for me)

I've bought parts from WrenchMonkey.ca and Partsavatar.ca a few times.
Strange website names, but they are legit as Canada Post delivers it and they have a pick up option as well.

Have a nice day!


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