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Ok so this isn't your standard "how can I get better gas mileage" thread. I know what I bought and I love it!

However.... 2005 with 250k miles. I'm averaging 10mpg when 95% of the time I'm driving miss daisy. 80/20 city/highway. I live in hilly Seattle. Occasional throttle goosing but I don't know that it really ever goes much past 3k rpm. I have the 420/430 codes, but that's all I can attribute to this. I changed my valve cover and it fixed the smoke issue so that's not messing with the af mix anymore. New pcv, New plugs.

Thoughts? Regular gammit of cleaning maf etc? Or are the codes my biggest problem? I mean, 10mpg at times okay fine, but AVERAGE? I put in 22 gallons yesterday with 225mi on the trip odo...
 

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your vehicle is old so no surprise its out of spec.
those codes indicate issues with your o2 sensors and cat.

coil packs ever been changed?
dirty maf . using cheaper petrol can potentially leave more deposits in the engine.
what plugs are you using?
you may have an exhaust leak at the cat. your o2 sensors can be fouled. the wiring may also be damaged.
intake air leaks
improper ignition timing (faulty ECM?)
have you checked the compression on the engine?
cat may need replacing
 

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Ok so this isn't your standard "how can I get better gas mileage" thread. I know what I bought and I love it!

However.... 2005 with 250k miles. I'm averaging 10mpg when 95% of the time I'm driving miss daisy. 80/20 city/highway. I live in hilly Seattle. Occasional throttle goosing but I don't know that it really ever goes much past 3k rpm. I have the 420/430 codes, but that's all I can attribute to this. I changed my valve cover and it fixed the smoke issue so that's not messing with the af mix anymore. New pcv, New plugs.

Thoughts? Regular gammit of cleaning maf etc? Or are the codes my biggest problem? I mean, 10mpg at times okay fine, but AVERAGE? I put in 22 gallons yesterday with 225mi on the trip odo...
I don't do much better...maybe 11 mpg average. 12 or more on long highway trips...14 tops! I stay on top of all maintenance and have not found any one thing that can make much difference. I've noticed in the Seattle area, our hills make it hard to get the same mileage as those in flat topographies overall.
 

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2007 QX56 RWD
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Ten sounds good for hilly area and 80 percent city driving. I can hit 16-17 mpg on long flat highway trips down here in Florida. I assume my city driving would have horrible mpg. I bought this for the size, safety, weight, and the beast that lives under the hood.

I'm also retired, so I'm not driving as much as I used to. If I was still living and working in Orlando, I cannot imagine how heinous the mpg would be.
 

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Discussion Starter · #5 ·
Thanks for the insight, folks. I'm not terribly worried about it, but I do like to keep things in better condition. I'll inspect the mani's for The Crack and plan on changing the O2's.
 

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I have an '04 LE with 176k. Around town I get 13.5 and on my last long trip I got 17.something. I live in south Texas where the highest point in the county is the landfill!!! So...pretty flat. I DO get on the fast pedal often enough, but still manage fair mileage. I also have the Uprev tune and long tube headers. 10 mpg sounds a little low?
 

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I guess I should mention that when I had the manifolds done and tune I ended up with a few errors, namely p0300, random multiple misfire, yeah try and chase THAT down. So I replaced all the plugs, injectors and coil packs and the upstream O2 sensors. I think a few other things like cps and did a good cleaning on the MAF. So it is really running like a brand new truck. Valve covers were leaking so did those at the same time.
 

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I range from 8 - 13 with the latter only on highway with a strong tail wind ;).

My question would be is your mileage worse than it was originally?

Acceleration is what kills MPG and you do a lot of that when stopping and going in a town/city.

A lot of posters over the years have claimed higher mileage but it always seems they are 2WD. 4x4 (even when not in use) seems to make the mileage worse - perhaps the additional weight.

I used to drive to the train station a lot (2 miles) with warming up the truck prior. I think my worse was 6 MPG in that scenario!

Unfortunately the competition seems to have gone past the Armada with more features/more power/efficient mileage. I do not think I will buy another when the time comes sadly.
 

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A lot of posters over the years have claimed higher mileage but it always seems they are 2WD. 4x4 (even when not in use) seems to make the mileage worse - perhaps the additional weight.
It is because even though the transfer case is disconnected between the front and rear wheels, your front wheels are still turning the front CV axles, the front diff, the front driveshaft, and the portion of the transfer case that drives the front wheels. With both the front diff and transfer case sitting in oil, you are having to turn the gears through that oil, and the front CV axles have thick grease in them that the axle joints are turning in, and so you end up with parasitic drivetrain loss, plus the additional weight.
 

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I range from 8 - 13 with the latter only on highway with a strong tail wind ;).

My question would be is your mileage worse than it was originally?

Acceleration is what kills MPG and you do a lot of that when stopping and going in a town/city.

A lot of posters over the years have claimed higher mileage but it always seems they are 2WD. 4x4 (even when not in use) seems to make the mileage worse - perhaps the additional weight.

I used to drive to the train station a lot (2 miles) with warming up the truck prior. I think my worse was 6 MPG in that scenario!

Unfortunately the competition seems to have gone past the Armada with more features/more power/efficient mileage. I do not think I will buy another when the time comes sadly.
I’m in a 2WD 2021 with the 7-speed. I average 15.7 overall. I can get 19.5 on the interstate. I don’t drive in the city too much. 5 miles to the kids school and 5 miles to the church, no stop & go traffic - I avoid town at all costs. You’re right about the 4WD, the extra unsprung weight & spinning parts up front drag it down for-sure. When I drive for work, it’s ALL hi-way…and TX is relatively flat. Loving this 7-8 seater and the MPG’s from the drivetrain.
 

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It is because even though the transfer case is disconnected between the front and rear wheels, your front wheels are still turning the front CV axles, the front diff, the front driveshaft, and the portion of the transfer case that drives the front wheels. With both the front diff and transfer case sitting in oil, you are having to turn the gears through that oil, and the front CV axles have thick grease in them that the axle joints are turning in, and so you end up with parasitic drivetrain loss, plus the additional weight.
Makes sense!

I’m in a 2WD 2021 with the 7-speed. I average 15.7 overall. I can get 19.5 on the interstate. I don’t drive in the city too much. 5 miles to the kids school and 5 miles to the church, no stop & go traffic - I avoid town at all costs. You’re right about the 4WD, the extra unsprung weight & spinning parts up front drag it down for-sure. When I drive for work, it’s ALL hi-way…and TX is relatively flat. Loving this 7-8 seater and the MPG’s from the drivetrain.
Only way I could get close to that is downhill with the engine off 💩
 

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Ok so this isn't your standard "how can I get better gas mileage" thread. I know what I bought and I love it!

However.... 2005 with 250k miles. I'm averaging 10mpg when 95% of the time I'm driving miss daisy. 80/20 city/highway. I live in hilly Seattle. Occasional throttle goosing but I don't know that it really ever goes much past 3k rpm. I have the 420/430 codes, but that's all I can attribute to this. I changed my valve cover and it fixed the smoke issue so that's not messing with the af mix anymore. New pcv, New plugs.

Thoughts? Regular gammit of cleaning maf etc? Or are the codes my biggest problem? I mean, 10mpg at times okay fine, but AVERAGE? I put in 22 gallons yesterday with 225mi on the trip odo...
Our ‘08 QX gets 13 around town and 16 highway. 9 or 10 when towing a trailer. Purchased new and now has 68k miles on it.
 

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Our ‘08 QX gets 13 around town and 16 highway. 9 or 10 when towing a trailer. Purchased new and now has 68k miles on it.
2004 qx56, 150k miles, 12 around town and 17 highway. So it's nice to see that I'm right in the ballpark here. My only complaint is the computer MPG is 1.5mpg optimistic. LOL. My numbers are actual miles/gallons. So if any of you are posting computer numbers, verify them.

P.S. I live in hilly Seattle area too- about 20 miles North. Going from my house to freeway I get 18. Coming back up I get 8 if I don't have to stop.
 

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I know this may sound silly, but where did you buy your plugs? What brand/model?

I changed the starter in our '08 last year and put in new Iridium plugs while I was in there. No CEL or codes, but after the change, we went from averaging around 13.6-13.9 indicated on virtually all tanks of fuel to 11.5-12.5 on all tanks. We've got almost 200k miles on our 4x4. KS roads, but a lot of short trips less than 3 miles.

I hate changing plugs that only have 10k miles or so on them, but I think they may not be genuine plugs or maybe this brand is junk. I did buy via Rock Auto, but they just don't seem quite as good as the old Bosch set.
 

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Ok so this isn't your standard "how can I get better gas mileage" thread. I know what I bought and I love it!

However.... 2005 with 250k miles. I'm averaging 10mpg when 95% of the time I'm driving miss daisy. 80/20 city/highway. I live in hilly Seattle. Occasional throttle goosing but I don't know that it really ever goes much past 3k rpm. I have the 420/430 codes, but that's all I can attribute to this. I changed my valve cover and it fixed the smoke issue so that's not messing with the af mix anymore. New pcv, New plugs.

Thoughts? Regular gammit of cleaning maf etc? Or are the codes my biggest problem? I mean, 10mpg at times okay fine, but AVERAGE? I put in 22 gallons yesterday with 225mi on the trip odo...
charge the air filter to a after market cold air intake it does make a difference i drive to phx from tucson 5 days a and i fill my tank once and can go there and back and still have gas leftover
 

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charge the air filter to a after market cold air intake it does make a difference i drive to phx from tucson 5 days a and i fill my tank once and can go there and back and still have gas leftover
I don't understand. That's like 226 miles round trip. And you fill over 20 gallons (it's a 28 gallon tank). How is that better? It's almost the same. Cold air intakes have been shown to be no benefit here. It's all hype.

He's getting a tad less but your data is way worse than mine. I get 17mpg on that type of trip. Heck I got over 18 in some areas like that. Seattle area is quite hilly everywhere. Only relatively flat roads are the freeways.
 

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Ok so this isn't your standard "how can I get better gas mileage" thread. I know what I bought and I love it!

However.... 2005 with 250k miles. I'm averaging 10mpg when 95% of the time I'm driving miss daisy. 80/20 city/highway. I live in hilly Seattle. Occasional throttle goosing but I don't know that it really ever goes much past 3k rpm. I have the 420/430 codes, but that's all I can attribute to this. I changed my valve cover and it fixed the smoke issue so that's not messing with the af mix anymore. New pcv, New plugs.

Thoughts? Regular gammit of cleaning maf etc? Or are the codes my biggest problem? I mean, 10mpg at times okay fine, but AVERAGE? I put in 22 gallons yesterday with 225mi on the trip odo...
Either from a cracked manifold(s) or clogged converters, the P0420/0430 DTCs are the reasons for the dismal gas mileage. Unless thats corrected, fuel trims will continue to be erratic.
 

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My wife likes to say I'm the mpg whisperer for every vehicle we've had. I usually can get the top published numbers pretty easy. I really do t drive like a hypermiler or anything. Just keep my foot out of it unless really necessary. It's a kid hauler for our 3 growing boys.
1 thing I started using a few years ago is fuelly.com. Basically, EVERY TIME you fill up (station doesnt matter) enter current mileage, cost per gallon you're buying & total gallons filled. It calculates it right then & keeps a great running tally for you to look at. You can enter notes too if say you pulled a trailer that time etc. I used to calculate my own every time but this gives me a "book" if you will to look back at. You can also research any vehicle out there to see where they fall as well as where you fall compared to others with your vehicle.

This was too long but hope it helps!
 
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