Calgary Jeep Association
4x4 Related Groups => Tech Talk => Topic started by: yjpaul on August 16, 2005, 07:39:26 PM
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Specs : 88 YJ 4.2L(258)
Ok, so i have been calculating my MPG for the last little while with amount filled at the pump and trip odometer readings. I did the calculations for KM to miles, and Litres to Gallons, and got realized that i was averaging 9-11 miles per gallon for city/highway. What numbers are you all getting? Im not running rich or anything. Is there anything i can do to help it?
Thanks guys.
~Paul
*Its just $20 every second day is getting to be a joke.
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and also my emissions matenience light is on. Could this be a faulty O2 sensor? Will it make a difference? because i swapped the carb with that stupid electronic mixture control for the cj carb that was used the year before the electronic stepper motor thing. What will replacing the o2 sensor do in my case? I just want the light off. And maybe its making my mileage worse somehow.
Thanks
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in addition to the specs on the first message, the truck has 31" tires on it and a 3 inch body lift.
~Paul
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I had O2 problems, well I had no O2. And gas milage blew. Installed new O2 and I get 60L goes 250 miles in city and 300 in country. Depending on driving habits of course.
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I just went from an '03 4.0L to an '05 2.4L. On my first tank of gas off the lot, I got 500Km out of her :) But my gas gague was reading wierd, because the gas light came on half way into the red, so I think I could have gone a little further. She sux on hills though compaired to the 4.0, but looking at gas prices today, I think I can live with it!
Not sure how much it will help since you only went to 31's, but putting new gears inyour diff will help a bit (if you haven't already)
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Herea a handy tool for most of us who understand mpg vs. k/L : http://www.eltcalendar.com/stuff/mileage.php
Anyway, I just drove from Moose Jaw yesterday and got 19.5 mpg (8.16K/L) in my 1991 YJ 4.0HO on 31"s. That was with a crosswind and holding an indicated 100km/h. I don't know the true speed since I put on these tires after my GPS was stolen, but I'd guess I'm doing a true 105km/h or so. I notice a huge mileage drop if I try to go much faster than this.
Oh, I'm still on the stock 3.08 gears too, turning about 1500rpm at that speed. Zero power on any kind of hill in 5th, :x
I've got all brand new ignition on my Jeep too, and I think that helped my mileage. New plugs, wires, cap, rotor and coil cost about 2 tanks of gas. Not sure about what you should expect from your motor though. How careful are you with tire pressures?
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i get 14.65 mpg in the city running 37" MTR's. (4.10 gears)
Tom
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and also my emissions matenience light is on. ...
Thanks
Do you mean the maintenance light in the cluster .. it's driven by a timer and can be ignored (most people remove the timer as it is a dealer replaceable item set to go off every 80,000 miles or so). My unit must have been up behind the dash in the middle .. when I had the dash out I found the 3 wires just hanging there .. :lol:
The 88 didn't have a sophisticated enough computer to fire off a light.
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I don't know how much the computer in the yj controls the carb but if you have an O2 sensor and a non computer carb in there you will get the emissions light. Replacing the o2 sensor will give you nothing, as you cannot govern the mixture with the carb you have. Basicly your computer is useless. You must now try to tune your carb manually. You also should check your ignition timing. On my scrambler I set the ignition advance to 16 degrees btc, and swapped in a ford large distributor with the bigger coil. I averaged 20 mpg on the hightway with 3.73's and 33X10.5 bfg at's. Make sure your air filter is clean, spark plugs and wires are good. Synthetic fluids are good for reducing friction, and increase fuel mileage. Check your tire pressure and ensure it is appropriate for you vehicle weight and tire size.
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http://www.jeeptech.com/wiki/index.php/Engine/Carter :idea:
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Try this link for your mileage http://www.royalbank.com/cgi-bin/carloan/gas.pl
It spits out all the different types of mileage figures really easy.
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My 89 YJ w/33's and 4.10's was sucking pretty bad as far as gas mileage goes. In early July I topped off the tank in Calgary and then drove back to Lethbridge. The gauge was reading so low I filled up in Coalhurst (a small town about 10 km short of my destination.
For the last half year I have been experiencing intermitting stalling and idling problems. A mechanic talked me into buying a new carb (after he adjusted it 2 times with no success). I also replaced the plugs, ignition coil, rotor and distributor cap.
Anyway, to make a long story short - after the YJ died and could not be started I finally managed to track down the culprit - it was the ignition control module (located under the radiator overflow bottle).
After it was replaced my fuel economy went way up (can't give you exact #'s a my kids keep resetting the trip odometer to zero on me.
I suspect that perhaps I wasn't getting the proper spark and as a result, the vehicle was using more gas?
Note: Some parts stores (I went to Auto Value) can test your ignition control mod to see if there is a problem.
Other than that it could be the usual culprits:
-dirty air filter
-bad plug(s)
-poor driving habits
-tire pressure
Hope this helps.
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I believe you guys are having some serious issues..I have been getting 60-65 MPG lately...ar..ar..ar
(http://i14.photobucket.com/albums/a342/SuperDaveMillard/Fullside1.jpg)
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13.5l/100km or 17.42mpg. I don't think anybody uses km/l, though it is kind of usefull to know how far the tank will take you.
This is highway only. City driving is worse. 35" Krawlers and about 5" of lift total. Heavy vehicle too - over 4900lbs.
Stock or nearly stock I was getting 10.5L/100km or 22.4mpg.
98TJ w/ 4.0L
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I get around 16.3L/100km according to my in dash computer thing in my 93 cherokee stock. I think its crap but we ve got to live with it.
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My milage for the second half of last week was:
Distance travelled: 416 Km
Amount of gas required: 53 Litres
Metric (Canada) 12.74 L/100KM
Metric (Europe) 7.85 KM/L
US Gallons 18.57 MPG
Imperial Gallons 22.17 MPG
2001 Stock TJ Sahara, 4L, 5 speed, Tires 235 Long Trail TA on 16" rims.
This was real mixed driving downtown daily, plus HWY and rural roads.
I expect the milage to go down next year if I can afford some modification. Any recomondatios for rear end gears if I move to 31" tires. I am planing to keep one set of street tires on rims for the week and a second set of mud tires for the weekend.
What is the best milage I can expect out of a 4L? Is any other 4L. geting beter milage?
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Any recomondatios for rear end gears if I move to 31" tires.
What gears do you have now? I'm on 31"s and have 3.08 gears, which turns 5th gear into overdrive - no hills or headwinds. I'm looking for 4:10s from a 4 cylinder.
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I have not confirmed what I have curently for rear end gears. The rear end is stock, as far as I know. I have the same problem on hills even with the 4L, unless I hit a hill at 120Km+ in 5th I start to drop a lot of speed. I think if I put lower gears in then fith will be more usefull and I will be able to run in ii more often.
If I go form 29" tires to 31" what change of gears would keep things the same and what would lower the ratio and make 5th more usefull?
Blair
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I have not confirmed what I have curently for rear end gears. The rear end is stock, as far as I know. I have the same problem on hills even with the 4L, unless I hit a hill at 120Km+ in 5th I start to drop a lot of speed. I think if I put lower gears in then fith will be more usefull and I will be able to run in ii more often.
If I go form 29" tires to 31" what change of gears would keep things the same and what would lower the ratio and make 5th more usefull?
Blair
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i use 33 inch tires with 4.10's and can still use 5th no problem,,so wouldnt worry to much about changing gears for 31,s
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What is the RPM @ 60mph in 4th?
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With my 4 banger, 4.10s and 31s I usually get 400-425 km in the city and 500-525 on the highway if i push it.
I would not recommend a 4.0L, 31s and 4.10. It will be too low. Talk to a rubicon owner and see what their mileage is
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BlackYJ,
what speed are you going on the highway?
I can get about 400-430kms in the city, but if I get on the highway @ 110 It's down!!! To like 350 kms a tank.....
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well here's your Rubi reply :D
might as well start off with my specs...
'03 Rubi with 4" lift and 33X14.5X15 TSL's
Aftermarket front and rear bumpers
winch
quick discos
onboard air
CB
and about 40lbs of recovery gear.
sadly by the looks of it i think i get more km out of a tank of gas on my street bike :( I don't have any real figures for you as i just bought it a couple of days ago and have only filled it once. btw this is my first post :D Hello All! so yeah. i figure i am going to MAYBE get 250km out of a tank of gas :evil: but what do u do...going to take it to dodge and get a tune up and see if that helps...hopefully lol
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Specs : 88 YJ 4.2L(258)
Is there anything i can do to help it?
Not really Paul.
We are all driving a 50 some year old motor. They just dont get great milage.
You could regear to operate at a better torque range, convert to fuel injection. Do about 10 other mods that claim milage increases which are really blowing smoke. ie, headers, intake, high power ignition, wear darker sunglasses, etc etc etc. Most of it is BS, and the very slight gains in milage never actually pay out.
But even with all that, it really wont change by any significant amount. Couple mpg if you are lucky.
The biggest mpg factor to jeeps is high speeds on the highway cause they are a box. Other then that, they just dont vary by much.
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With my 4 banger, 4.10s and 31s I usually get 400-425 km in the city and 500-525 on the highway if i push it.
I would not recommend a 4.0L, 31s and 4.10. It will be too low. Talk to a rubicon owner and see what their mileage is
Most rubs average between 14-17mpg depending on how modded they are.
Thats with being at least 500lbs heavier then a sport when they are stock.
4.10''s an 31's is about right. Still a bit weak.
Better milage would be 4.56's, 31's, staying at or under 90kph.
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With my '89 XJ and 5spd I got close to the same milage with 31s and 4.10s as I did with 215s and 3.08s. But I had lots more power, on street and trail. With the 3.08s and 215s I almost always had to downshift or hold the pedal right to the floor to maintain speed on any kind of hill. With the 4.10s/31s I did not need to downshift nearly as much. I think the stock 3.08 gears are way too overdriven for a Jeep.
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I had O2 problems, well I had no O2
.....................wouldn't you have a check engine light come on if the o2 sensor was bad???
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500-525 on the highway if i push it
...................Black YJ i seriously doubt you get a 500km range witha full tank in your YJ. If you posted this on www.jeepforum.com you would seriously get challenged by a ton of die hard jeepers. I don't think a distance of 500 kms could be achieved even if you were doing a paltry 60 kms/hour on the highway. :roll:
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On a recent trip to Waiparous from Calgary with some off roading ( Lost Knife and Meadow Creek trails ), back home and some city driving my fuel consumption was 15.7 L / 100 km. '95 YJ, 2.5 L, stock 4.10 gearing, 2.5" lift, 31" M/Ts, winch, hard top, rock crawler rear bumper, rear locker, some tools and recovery gear, recent cleaning of the K&N, and plugs changed in the spring. Cruising @ 100 - 110 km/hr on the highway. It has been better and worse.
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500-525 on the highway if i push it
...................Black YJ i seriously doubt you get a 500km range witha full tank in your YJ. If you posted this on www.jeepforum.com you would seriously get challenged by a ton of die hard jeepers. I don't think a distance of 500 kms could be achieved even if you were doing a paltry 60 kms/hour on the highway. :roll:
Why the need to call him a liar? There are tons of people getting 500+ kms out of a tank, myself included. Check this thread out:
http://www.missioncontrol.ca/cgi-bin/YaBB/YaBB.cgi?board=Eco;action=display;num=1126732248
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Why the need to call him a liar? There are tons of people getting 500+ kms out of a tank, myself included. Check this thread out:
..................i should have clarified myself. With the 72 liter tank sure, but not with the 60 liter tank which i have.