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Poor fuel economy?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=84685		 Page 1 of 1
Author:  Maickdd [ Sat May 28, 2016 12:32 pm ]
Post subject:  Poor fuel economy?
Hello,

After installing my lift and larger tires in last october, I have been keeping an eye on my the fuel consumption of this little beast.

After totalling my refills I decided to count my avg. mpg over the last few months the number was 16.16 with 20 refills. This includes the coldest months here in Finland and such but still it seems a little poor. I havent really driven that much, about 15000km after purchasing this thing.

Things I have done that hurt my MPG:
- Lift (OME 790 + 1/2" clevis, 948 at the back) fender to hub is something like 52cm
- Bigger tires, 265/65/17 GoodYear Wrangler Ultragrips (useless as winter tyre btw)
- Renegade Roof Rack until march (didnt notice much of an improvement mpg wise, that goddamn thing needs some reinforcing before Ill install it again)

Thermostat was replaced almost immediately after I bought this vehicle in 08/15, MAP cleaned 08/15, Engine and tranny tune 08/15, brakes done 08/15, all oils and air filter (tranny, differentials, engine) 08/15, Turbo to CAC Hose 11/15. Oil + air filter changed in 11/15 again because I had a few cans at hand and wanted to be sure I was running suitable oil for the winter months.

No codes apart from occasional turbo underboost code during cold months (like once or something, tuneup guy told me that it could be related to his software (?)), clears itself after few warm up periods.

Whats next on my check list? Air in fuel problems or injectors (eek)? Fuel filter I havent replaced I think I have it lying somewhere waiting for someone (me) to replace it.
Author:  PALiftedKK [ Sat May 28, 2016 12:57 pm ]
Post subject:  Re: Poor fuel economy?
With diesel being more efficiant then a gasser, ~16mpg with a lift and withoit regearing is really good. The gasser libertys get far worse then that. Just make sure the turbo is getting its oil and no exhaust leaks.

Dont forget to that when any vehicle is lifted fuel economy will never ever be the same again. In a well built rig mpg may take a 2 mpg loss. Not bad at all.
Author:  papaindigo [ Sat May 28, 2016 1:07 pm ]
Post subject:  Re: Poor fuel economy?
Before going any further we need more information to offer comments:
1. is that 16.16 mpg figure in US gallons/Imperial gallons/metric conversion (I note Finland is a metric system country)?
2. was that # based on EVIC or hand calculated with GPS corrected mileage? EVIC mpg is known to be inaccurate and inconsistent between CRDs.
3. yes a lift would increase air resistance and drop mpg but a change in tire size should not result in much change in ACTUAL mpg although it will throw off odometer and EVIC figures. See 2 above.
4. information of ambient temps and driving habits would also help. It matters if ambient temps are low (mostly below freezing) and your drives are shortish distance without fully warming up the vehicle as opposed to higher temps and longer drives.
5. what's your typical average driving speed?
6. I see you have a new thermostat. Is it OEM style and once vehicle is warmed up where does the temp gauge needle point?

An actual 16.16mpg is low. Best I can say is both my 05s got about 18-19 in town (not cold, 10 mile commute, average speed 25mph, few hills, some traffic lights) vs. 25-26 on the hwy (with/wo AC, average speed 62mph/1800rpm, generally flat roads, few stops). Actual long term average of course would depend on mixture of in town vs. hwy.
Author:  Maickdd [ Sat May 28, 2016 2:14 pm ]
Post subject:  Re: Poor fuel economy?
papaindigo wrote:
Before going any further we need more information to offer comments:
1. is that 16.16 mpg figure in US gallons/Imperial gallons/metric conversion (I note Finland is a metric system country)?
2. was that # based on EVIC or hand calculated with GPS corrected mileage? EVIC mpg is known to be inaccurate and inconsistent between CRDs.
3. yes a lift would increase air resistance and drop mpg but a change in tire size should not result in much change in ACTUAL mpg although it will throw off odometer and EVIC figures. See 2 above.
4. information of ambient temps and driving habits would also help. It matters if ambient temps are low (mostly below freezing) and your drives are shortish distance without fully warming up the vehicle as opposed to higher temps and longer drives.
5. what's your typical average driving speed?
6. I see you have a new thermostat. Is it OEM style and once vehicle is warmed up where does the temp gauge needle point?

An actual 16.16mpg is low. Best I can say is both my 05s got about 18-19 in town (not cold, 10 mile commute, average speed 25mph, few hills, some traffic lights) vs. 25-26 on the hwy (with/wo AC, average speed 62mph/1800rpm, generally flat roads, few stops). Actual long term average of course would depend on mixture of in town vs. hwy.


1. US Gallons, 14.55 l/100km

2&3. Hand calculated (trip from jeep kms and litres from the gas station)

4. Commuting, approx. 15 - 45kms per warmup, mostly. Ambient temperature in measured period ranges from +10 to -28 celsius. Below freezing, I use the block heater during nights, no plug at work. So after night its preheated but not when leaving work.

5. Avg. Speed must be something around 50-60km/h.

6. Thermostat is fine, needle is at the middle of the scale or very slightly below. OEM stat. The aftermarket would cost a fortune with tolls and vat.
Author:  papaindigo [ Sat May 28, 2016 2:25 pm ]
Post subject:  Re: Poor fuel economy?
Generally I'd call those conditions cold weather in town commuting (temps chilly to below freezing, speeds ca. 35 mph, distance 10-25 miles) probably mostly with what we in the USA call "winter" fuel. Winter fuel probably costs you 10% mpg maybe more. You really need to check your odometer against a GPS as I've seen errors upto +-5% and of course your tire size is impacting odometer accuracy.

Under those driving conditions absent a lift I'd expect ca. 17-18 or maybe a bit less GPS corrected mpg.
Author:  Maickdd [ Sat May 28, 2016 2:51 pm ]
Post subject:  Re: Poor fuel economy?
papaindigo wrote:
Generally I'd call those conditions cold weather in town commuting (temps chilly to below freezing, speeds ca. 35 mph, distance 10-25 miles) probably mostly with what we in the USA call "winter" fuel. Winter fuel probably costs you 10% mpg maybe more. You really need to check your odometer against a GPS as I've seen errors upto +-5% and of course your tire size is impacting odometer accuracy.

Under those driving conditions absent a lift I'd expect ca. 17-18 or maybe a bit less GPS corrected mpg.


Ofcourse there have been longer trips aswell during that time. Even accounting a 5% odometer error that would bring the consumption to 13.7 or so.

So my fuel economy is normal for these harsh conditions? I will be getting a grille mounted radiator cover for next winter and see if it helps.
Author:  flash7210 [ Sat May 28, 2016 2:55 pm ]
Post subject:  Re: Poor fuel economy?
About 18 months ago, I lifted mine 1 inch and went with some aggressive all terrain 245-76-16 tires.
My MPG dropped from 25-27 to 21-23.

I hate the fact that my MPG has dropped so much but those tires have been damm good off-road.
Author:  thermorex [ Mon May 30, 2016 7:43 pm ]
Post subject:  Re: Poor fuel economy?
Changing the tire size will throw your odometer off, unless you recalibrate it, and as I know you can only do this with a drb3. What I am saying is that you may go 100 miles on your odo, when in reality you drove 110 or 120 miles. Just trying to make sure you factored that in your mileage.
Author:  The Scott McLean [ Mon May 30, 2016 8:17 pm ]
Post subject:  Re: Poor fuel economy?
When have you had your brakes last looked at?

Here in Canada we get close to the same temperatures in the winter. I can tell you, 10-12L / 100 km is as good as I can get. Diesels like to be warm.

Winter fuel sucks.

If your only getting up to 10 C remove your rad fan. You don't need it, at those temperatures.

GDE suggest removing the snorkel from air box, for a small improvement.

Brakes must be serviced regularly. They stick and hold on, nuking your mpg. I service mine twice a year.




Sent from my Nexus 5 using Tapatalk
Author:  Rixram [ Thu Jun 02, 2016 11:23 am ]
Post subject:  Re: Poor fuel economy?
The Scott McLean wrote:
When have you had your brakes last looked at?

Here in Canada we get close to the same temperatures in the winter. I can tell you, 10-12L / 100 km is as good as I can get. Diesels like to be warm.

Winter fuel sucks.

If your only getting up to 10 C remove your rad fan. You don't need it, at those temperatures.

GDE suggest removing the snorkel from air box, for a small improvement.

Brakes must be serviced regularly. They stick and hold on, nuking your mpg. I service mine twice a year.

Sent from my Nexus 5 using Tapatalk


Note that when doing the brakes, I'd encourage replacing the calipers as well. I noticed a boost in efficiency once I replaced those. The stock calipers tend to lead to brake drag, which, yes, nukes your efficiency.
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