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Poor MPG

 
  #46  
Old 02-14-2019, 07:58 PM
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Okay, update time. I got 285.1 miles before the fuel light came on.

Filled up, 36.6 gallons in until click off. After which, the nozzle wouldn't pump anymore, actually felt like it had broken. That said, gauge reads full.

My maths says this tank yielded me 7.8mpg.

Not bad, in comparison. Still not great though. Can I chalk some of this up to snow covered roads and using 4WD (or locked hubs even in 2WD) a lot?

Not to mention the -10 weather we've been having recently...
 
  #47  
Old 02-14-2019, 09:28 PM
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Much better.

Now, just to be on safe side look under fuel tank and make sure there isn't a leak when full. A hole high up on tank could only leak when tank is full.

Tire size...if your tires are larger than oem than your miles are off. 34" tires and you need to add about 5% or so to your miles.
Next I would check brakes and hubs to make sure nothing is dragging.

Then I would check for leaking exhaust manifolds. Any exhaust lost via a bad gasket will make O2 sensors read lean and the pcm will richen up air fuel ratio causing poor fuel mileage.

Then check pcm for any codes.

End .....for most as code check might tell you where to go next.

I personally would also put in new plugs, coils, MAF, IAC, fuel pressure regulator, and get refurbished injectors too. I know that's about $500 to $700 in parts but that just what I would do. I know everyone can't do this.

On a side note, is your thermostat a 185 degree unit? Being in a cold climate I suspect you may have a hotter tstat? This could, I'm not 100% positive, confuse the pcm as to how it calculates the optimum air fuel ratio.
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  #48  
Old 02-15-2019, 10:41 AM
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Originally Posted by BatteriesNotIncluded View Post
Okay, update time. I got 285.1 miles before the fuel light came on.

Filled up, 36.6 gallons in until click off. After which, the nozzle wouldn't pump anymore, actually felt like it had broken. That said, gauge reads full.

My maths says this tank yielded me 7.8mpg.

Not bad, in comparison. Still not great though. Can I chalk some of this up to snow covered roads and using 4WD (or locked hubs even in 2WD) a lot?

Not to mention the -10 weather we've been having recently...
i have seen as low as 9mpg this winter, so if your driving was all city that seems good.

Do you know if you have 3.73 or 4.30 gears? I have 4.30 and I consistently average about 30% less than my coworkers who has 3.73 gears
 
  #49  
Old 02-15-2019, 10:48 AM
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Originally Posted by Flyboy1100 View Post


i have seen as low as 9mpg this winter, so if your driving was all city that seems good.

Do you know if you have 3.73 or 4.30 gears? I have 4.30 and I consistently average about 30% less than my coworkers who has 3.73 gears
3.73 gears with stock tires. I've been toying with going to 4.88's actually. What size tires have you got? 37's?
I've not run this truck in any weather other than snow yet (it is that new) so I'm holding off rash decisions until it's run on clean roads and warmer air. I'm happy to hear I'm not too far off what you've seen in winter though.

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Last edited by BatteriesNotIncluded; 02-15-2019 at 02:02 PM. Reason: Mistyped
  #50  
Old 02-15-2019, 11:06 AM
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Originally Posted by BatteriesNotIncluded View Post
3.73 gears with 35 tires. I've been toying with going to 4.88's actually. What size tires have you got? 37's?
I've not run this truck in any weather other than snow yet (it is that new) so I'm holding off rash decisions until it's run on clean roads and warmer air. I'm happy to hear I'm not too far off what you've seen in winter though.

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33” tires.

Are you accounting for the tire size in your calculation, because that will make a huge difference since your odo will really be underreporting with a 3.5” taller tire than stock. Unless of course the PO had that adjusted in the computer. Oddly enough with 33” tires and factory 4.30 gears my odo/mph are exactly spot on but with factory size they were off....
 
  #51  
Old 02-15-2019, 01:08 PM
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You are dead on for my winter MPG. I'm between 7 and 8 MPG as low as the 6's if it's cold. That's running in 4x4 100% of the time and considerable idle time. GPS verified.

I also have the same issue with my gauge not reading correctly. I've had 3 V10 Excursions and my current one is all wonky. My other two it was very clear 1/4 was 10 gallons gone, 1/2 was 20 gallons gone, 3/4 was 30 gallons gone and E left me with 4 gallons, every. single. time. My current one turns the gas light on, drops the gauge to E and says 0 miles to empty when I can only pump 36-37 gallons in it, very aggravating as I've replaced the fuel pump and sender trying fix the problem but.
 
  #52  
Old 02-15-2019, 01:45 PM
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Originally Posted by WE3ZS View Post
What size tires are on it and what pressures do they have in them?
Originally Posted by BatteriesNotIncluded View Post
Got the stock size tires on it. No lift. Front have 47PSI and rear have 52 PSI - so a slight imbalance from the 45/55 it should have.
Originally Posted by 1 Excursion camper View Post
Donyou have a lift with larger tires and stock gearing. Or is everything stock?
Originally Posted by BatteriesNotIncluded View Post
Everything is stock.
Originally Posted by BatteriesNotIncluded View Post
3.73 gears with 35 tires. I've been toying with going to 4.88's actually.

OK, now that you have clearly stated that you have BOTH stock (31.6") sized tire's AND 35" tires, it will be very helpful to the folks here trying to be helpful if you could tell us EXACTLY what size tire's your EX has on it. . The actual tire size can be a very large factor in figuring out the real world mileage you are getting.
 
  #53  
Old 02-15-2019, 01:46 PM
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With 35" tires you are about 11 to 12% off on miles driven.

So your mileage is closer to 8.7 mpg

still not as good as it should be. I average 11.5 on my supercharged X with 4.10 equivilant gears and 13 mpg in my other 2 excursions with 3.73s. And that's at 8000 ft elevation.

Much better than 4.5 mpg though.
 
  #54  
Old 02-15-2019, 02:00 PM
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Sorry I mistyped!

I meant to put I am thinking of getting 35's down the road.

I DO have stock tires. 265/75/R16 @ 31.6"

 
  #55  
Old 02-15-2019, 02:08 PM
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Originally Posted by BatteriesNotIncluded View Post
Sorry I mistyped!

I meant to put I am thinking of getting 35's down the road.

I DO have stock tires. 265/75/R16 @ 31.6"
Thank you, I was getting a bit confusicated there.............
I think maybe checking for a miss might be worth the time. You can carefully unplug each COP one at a time to see if the idle changes, if you find one (or more) that do not affect the idle when unplugged, that cylinder has a miss. Running with a miss too long can eventually trash the catalytic converter as well as put a dent in the MPGs.
 
  #56  
Old 02-15-2019, 02:27 PM
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Originally Posted by WE3ZS View Post


Thank you, I was getting a bit confusicated there.............
I think maybe checking for a miss might be with the time. You can carefully unplug each COP one at a time to see if the idle changes, if you find one (or more) that do not affect the idle when unplugged, that cylinder has a miss. Running with a miss too long can eventually trash the catalytic converter as well as put a dent in the MPGs.
its amazing how smooth the v10 will run on 9 and even 8 if the correct 2 are out.......
 
  #57  
Old 02-15-2019, 05:47 PM
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Originally Posted by Flyboy1100 View Post


its amazing how smooth the v10 will run on 9 and even 8 if the correct 2 are out.......
One of the "benefits" of so many cylinders.
But you should still hear the difference of intentionally shutting one off. Or unplugging one and NOT hearing a change!
 
  #58  
Old 02-15-2019, 08:52 PM
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Originally Posted by WE3ZS View Post
One of the "benefits" of so many cylinders.
But you should still hear the difference of intentionally shutting one off. Or unplugging one and NOT hearing a change!
exactly, i did this, then confirmed with mode $06 data. It was much faster to unplug coils
 
  #59  
Old 02-16-2019, 04:24 AM
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Originally Posted by WE3ZS View Post


Thank you, I was getting a bit confusicated there.............
I think maybe checking for a miss might be worth the time. You can carefully unplug each COP one at a time to see if the idle changes, if you find one (or more) that do not affect the idle when unplugged, that cylinder has a miss. Running with a miss too long can eventually trash the catalytic converter as well as put a dent in the MPGs.
​​​​​​Interesting. It would be my first time doing something like this, are there any good videos on it? I know it's simple enough, but watching others is how I learn best.
Also, my truck runs OBDII software. Hood confirmed. Will a scanner detail this easier for me than the unplug test?
I've also bought a 22-inch screwdriver to do the injector listening test. I'm sure my new neighbours will think I'm mad!
Thanks guys - your help is amazing.
 
  #60  
Old 02-16-2019, 06:38 AM
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Originally Posted by BatteriesNotIncluded View Post
​​​​​​Interesting. It would be my first time doing something like this, are there any good videos on it? I know it's simple enough, but watching others is how I learn best.
Also, my truck runs OBDII software. Hood confirmed. Will a scanner detail this easier for me than the unplug test?
I've also bought a 22-inch screwdriver to do the injector listening test. I'm sure my new neighbours will think I'm mad!
Thanks guys - your help is amazing.
its super simple.

1. Pop hood
2. Start engine
3. Unplug a 1 coil at a time

there will either be a distinct change in idle/smoothness/sound or there won’t. If there isn’t that one is dead

why didnt uou buy a 5.00 stethoscope from harbor freight instead of a screwdriver?
 

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