Excursion MPG vs. Small SUV's MPG - Page 3 - Diesel Forum

Maverick4x4 · 07-19-2005, 05:57 PM

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I all that has changed is the the tire, then I'd be thinking it was the tire.

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it's just a lot to drop cuz of tires, and that's got me spooked. I wish I would have waited a while before swapping the tires over, to get a better baseline.

For the next few tanks, I'm gonna monitor it for each kind of driving that I do: mtn trips, driving to work, towing, etc. I'll be haulin' the scouts to camp next mon, and back the following sat, so that should be some steady highway miles at prudent speeds.

jogiba · 07-20-2005, 11:41 AM

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Please note: I'm trying to get back to 15 mpg. I'm now at 11 mpg. I'm driving using all the tips. IS IT THE G#*&$@#$M TIRES????? OR SOMETHING ELSE?????

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If you did not adjust the odometer/computer for the taller tire your MPG numbers will not be accurate.

Maverick4x4 · 07-20-2005, 11:50 AM

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Please note: I'm trying to get back to 15 mpg. I'm now at 11 mpg. I'm driving using all the tips. IS IT THE G#*&$@#$M TIRES????? OR SOMETHING ELSE?????

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If you did not adjust the odometer/computer for the taller tire your MPG numbers will not be accurate.

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You are correct, sir, if I hadn't...but unfortunately for me, that only accounts for a 3.7% difference, now I need to find the other 23%...

Tires are sold, just need to find the right ones to put on it now. My piggy bank is almost empty.

walt501 · 07-20-2005, 01:46 PM

Good points here, I'll add that the fuel you use is a major factor in your mileage. Locally (Minnesota) I've been using Koch Refining Gold Diesel - claimed higher cetane numbers. My truck is completely stock. So 2 weeks ago I filled up with Gold diesel for a 350 mile trip with 500lbs of gear on board pulling a 600 pound boat and trailer. Kept my speed between 60 and 65, and filled up at the end of the trip. 19.93mpg hand calculated - pretty good! My overhead was reading slightly over 20, so pretty close to actual number. On the way home, I filled up with Brand X diesel. I couldn't hit 18mpg when I re-set the overhead! This week I had to head north again for some minor body work (hit a deer). Filled up with Gold diesel for the 135 mile return trip. I held the speed at 58mph using the cruise all the way home. Truck was completely empty, except for me, and the road was level with few hills. I did every trick I know to conserve fuel - slow down until the light changes to avoid a complete stop, slow take-offs from a stop sign, tires at 60lb front, 65lb year. Take a guess at what my overhead read when I pulled into the driveway? 27 MPG! Now, maybe my overhead was reading a little high, but still......

Fuel makes a big difference. Shop around and find the best diesel in your area.

AllAboutJeeps · 07-20-2005, 04:47 PM

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The only change between the test drive tank and the 2 subsequent tanks was swapping aggressive Coopers (285) for the road tread Michelins (265), with both tires showing a need for an alignment. The V-codes came halfway through the 1st tankful. But a 41% drop in economy from 1" taller, more aggressive tires??? (even adjusting for the taller tire, it still sucks) Help me out here.

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Mav,

Seems like a big drop for just tires. Is it possible you got a bad batch of fuel and plugged up your fuel filter? A dirty fuel filter can kill mileage big time. How about your air filter? Did you feel a notable loss in power? I can't imagine tires having THAT large of an effect, especially unloaded just driving around town. I feel for you and wish I could offer better advice.

...danny

Maverick4x4 · 07-20-2005, 07:37 PM

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The only change between the test drive tank and the 2 subsequent tanks was swapping aggressive Coopers (285) for the road tread Michelins (265), with both tires showing a need for an alignment. The V-codes came halfway through the 1st tankful. But a 41% drop in economy from 1" taller, more aggressive tires??? (even adjusting for the taller tire, it still sucks) Help me out here.

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Mav,

Seems like a big drop for just tires. Is it possible you got a bad batch of fuel and plugged up your fuel filter? A dirty fuel filter can kill mileage big time. How about your air filter? Did you feel a notable loss in power? I can't imagine tires having THAT large of an effect, especially unloaded just driving around town. I feel for you and wish I could offer better advice.

...danny

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entirely possible...I reset the 'puter when I filled up the night I put the tires on...it read 15-16 until the next day, then dropped to 13, then to 11ish. Conversely, the last tank was filled near the freeway, and the mileage never got above 12 (mellow driving, using all tricks)

Sounds like I need to learn about diesel fuel filters...

ScaldedDog · 07-20-2005, 08:32 PM

I've figured out that my wife's 05 Infiniti G35x is just about as expensive to drive as my 01 X. She gets a little better mileage (18 vs 16), but has to use premium gas.

Of course, she has real leather seats, a sunroof and other things usually associated with a fine car, but I have torque! :-)

Mark

DieselFan · 07-20-2005, 10:17 PM

Maverick, here's my $.02... Why don't you give this a try. This will tell you if it's wind resistance or rolling resistance. Reset your computer and drive on a flat surface at 55 MPH for ten miles or so to see what your mileage is during that run. Hold it at 55 because wind drag will make a big difference. If your mileage is around 23 during that run, it's most likely wind resistance that's killing you. If your average is lousy no matter what, it could be the tires. This is assuming you haven't done anything else.

Did you lift the truck any when you put the larger tires on? That raises wind resistance. A larger patch of rubber on the road increases rolling resistance. On a eighteeen wheeler, the difference in wind drag between 70 MPH and 55 MPH is 40%.

I've got 265 BFG T/A AT's on my truck and at 55 MPH I average about 23-24 MPG after a reset as long as I can hold it there. And that's about as good as it gets. Everything else I do drags that average down. [img]/ubbthreads/images/graemlins/shrug.gif[/img]

DieselFan · 07-20-2005, 10:23 PM

Yeah, my wife's Acura gets about 3 MPG better than my truck, but the premium fuel requirement erases any advantage.

We carpool now in my truck and she can sit there and read, do the makeup thing, fiddle with the radio and her favorite pasttime is to give me heck. But my gas bill has decreased from $380 a month down to $200. A hundred dollar bill ever two weeks ain't too bad these days. [img]/ubbthreads/images/graemlins/rolleyes.gif[/img]

AllAboutJeeps · 07-21-2005, 04:57 PM

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Yeah, my wife's Acura gets about 3 MPG better than my truck, but the premium fuel requirement erases any advantage.

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That must be nice. Last time I filled up, I paid $.10 more than premium [img]/ubbthreads/images/graemlins/shrug.gif[/img] [img]/ubbthreads/images/graemlins/vomit.gif[/img] [img]/ubbthreads/images/graemlins/rolleyes.gif[/img] !

But back on topic.

Mav,

Definately check the fuel filter! It can have a drastic effect on mileage, almost as drastic as the one you have described. On the main TDS page it explains how to do it. Really easy. Heck, you don't even have to change it, just open up the resevoir and see if it is dirty.

Happy hunting and good luck.

...danny

DOGdiesel316 · 07-24-2005, 05:37 PM

Cruising level ground at 55 is 21-22 towing my Vette on a heavy trailer 7,000 plus total I get 15 going from Long Island to Pocono with some nice hills. I was running with a gas X and could walk it on the hils so easy I couldn't beleive it. Love the truck and diesels

rechinca · 08-09-2005, 12:22 AM

semi-related, but the 2000 Explorer 4x4 with the 4.0 I traded in on this thing averaged 12 at best in town and a whopping 16 on the freeway with a stiff class 5 tornado behind it!!! And the tree huggers want to kill the Ex because how much it hurts the environment!?!? I beat the best freeway I had with the Exploder on my intown with a lift and 33's!!!

pedal2metal · 08-12-2005, 01:11 AM

Mav,
I would have to say that there is something wrong. I would definately check fuel filter, and air filter. that is way too much of a drop due to that small of a tire size increase. I didn't see what year of X and engine you have?

Maverick4x4 · 08-13-2005, 07:42 PM

Thanks. I'm looking at the air and fuel filters today. The air filter is a K&N rechargable. I'm "recharging" it....but I think I'm gonna just buy a regular one from the store and see what happens. I logged on here to see about checking the fuel filter, since I have no idea what I'm looking for once I find it. ok, I have a bit of an idea, but I don't know how dirty is too dirty (might just buy a new filter too...if autozone carries such a thing)

Hell of a time to get crappy mileage, with the way prices are gettin' hiked.

(a few hours later)

DieselFan, I took your advice and after changing my fuel and air filter, I fueled up ($2.65 cough) and got on the I-15 freeway through SLC. After setting the cruise on 55 (54, but I have 285's so I figure it was close) I felt like a rock in the river, the way that traffic flowed around me. I also turned off the A/C, since I was going for a baseline best.

The first 10 miles, I got between 26.8 and 26.3 mpg!!!! I took an exit onto another highway (201) that I knew had a cloverleaf at the belt interchange (I-215).

I maintained 26.3 up to the cloverleaf @ 16 miles. It dropped to 25ish between that cloverleaf and the short stretch back to the first freeway. The ramp to the first freeway has a long uphill and it dropped me into the mid-24's. I stayed in the 24's all the way back to my exit, ending at 24.5 mpg. Driving from the freeway to my house, it dropped to 23.0mpg.

Conclusions: I can never start, stop, speed up or slow down. No hills, and I can only make left turns...:-) Basically, the stop and go is killing the mpg, and probably the short trips too.

But hey, the power is great, and I've towed my jeep a couple times now, and really love it. Coming from a burb, I knew the value of the third row, and a family trip yesterday made me happy I got the X rathe than a crew cab (4 boys: 1 sleeping in a kid seat in the reclined 2nd row, 2 watching the dvd with wireless headphones, one playing a video game. all spread out with plenty of space).

Thanks all for your suggestions!

Brett