brdhntr Posted January 14, 2009 Share Posted January 14, 2009 so what kind of gas mileage is everyone getting? i'm curious because the gas mileage of my mj really matters to me. with what i use it for, i really watch the mileage. i have the 2.5 in my '87. the trips i have taken so far i have gotten an average of 21.53 mpg. that's at 75 mph, windows up, and no air on. i thought that was great, but now i'm putting bigger tires on it and i'm hoping a few upgrades to the ignition will keep me around there still. i don't know for sure around town, the couple times i've checked it it's been around 17.5 mpg. i run 89 octane with ethanol usually. the trips down the road i've taken have both been mildly loaded and unloaded. i haven't figured it out with a large load yet. Link to comment Share on other sites More sharing options...
mvusse Posted January 14, 2009 Share Posted January 14, 2009 4wd, 4l Renix, AW4 automatic. I average about 17mpg, mostly town driving. Extended highway trips I get 24 at ~60 mph, 19 at ~75 mph. Link to comment Share on other sites More sharing options...
BLHTAZ Posted January 14, 2009 Share Posted January 14, 2009 The ONLY thing that will keep your MPG up when going to bigger tires is the proper gearing. Ignition changes will be a waste of money unless the stuff is in really bad shape and is hurting you to begin with :thumbsup: Mine is 4.0L, 5 SPD, 4WD, 31" tires, 3.07 gears = 15-17 mpg in town...don't do any hwy driving so I can't quote that. Link to comment Share on other sites More sharing options...
89eliminator Posted January 14, 2009 Share Posted January 14, 2009 4.0/AW4/231, 33s with 4.10s. Best tank to date was 20mpg. Usually average around 16-18 though. Link to comment Share on other sites More sharing options...
Pete M Posted January 14, 2009 Share Posted January 14, 2009 so what kind of gas mileage is everyone getting? i'm curious because the gas mileage of my mj really matters to me. with what i use it for, i really watch the mileage. i have the 2.5 in my '87. the trips i have taken so far i have gotten an average of 21.53 mpg. that's at 75 mph, windows up, and no air on. i thought that was great, but now i'm putting bigger tires on it and i'm hoping a few upgrades to the ignition will keep me around there still. i don't know for sure around town, the couple times i've checked it it's been around 17.5 mpg. i run 89 octane with ethanol usually. the trips down the road i've taken have both been mildly loaded and unloaded. i haven't figured it out with a large load yet. Are you at least swapping the little speedometer gear to keep your odo accurate with the bigger tires? Link to comment Share on other sites More sharing options...
brdhntr Posted January 14, 2009 Author Share Posted January 14, 2009 i don't know if i'll change the gearing or even the speedo gear. i'm used to a speedo being off. i just time it and figure it out when i make the change so i know for sure how fast i'm going. speedo's can be wrong (and often are). i'm not making a huge jump, only 2 sizes. i'm not going to big tires or anything. i am going from 215 to 235. i have the calculation already of how far off things should be. i've also asked on here and everyone seams to think the jump to 235's aren't a problem. if i decide to go with 30" or up i'll add a lift and change the gearing, but right now it's not an offroad vehicle, just off highway a bit. ;) Link to comment Share on other sites More sharing options...
SuperWade2 Posted January 14, 2009 Share Posted January 14, 2009 bout 1 tank per month... Link to comment Share on other sites More sharing options...
aemsee Posted January 14, 2009 Share Posted January 14, 2009 87 2.5 AW4 4x4 4.56 gears 235/75/15 tires. btwn 20 and 23. Mixed driving. I drive it like a little old lady though. If you have an option, don't buy the gas with the ethanol in it. Link to comment Share on other sites More sharing options...
manche Posted January 14, 2009 Share Posted January 14, 2009 i am only getting about 16-18 on a 89 2.5l but thats based on my stock odometer gear i am running 235x75x15 and i figure I'm off due to that but how much am i off by ?? Link to comment Share on other sites More sharing options...
Randy in Maine Posted January 14, 2009 Share Posted January 14, 2009 Gasohol and winter will also take a toll on your mileage. Link to comment Share on other sites More sharing options...
aemsee Posted January 14, 2009 Share Posted January 14, 2009 i am only getting about 16-18 on a 89 2.5l but thats based on my stock odometer gear i am running 235x75x15 and i figure I'm off due to that but how much am i off by ?? I'm running the same size and my speedo is off 4 MPH +/-. Remember when you calculate MPG that you have actually traveled further than the odometer shows so your MPG will be slightly better. Link to comment Share on other sites More sharing options...
BLHTAZ Posted January 14, 2009 Share Posted January 14, 2009 If you don't change the speedo gear, you cannot possibly calculate a correct mileage. I wish we could buy gas without Ethenol, but they put it in all gas now from what I understand. Ethenol definitely reduces MPG and causes damage to these older vehicles fuel systems. Link to comment Share on other sites More sharing options...
aemsee Posted January 14, 2009 Share Posted January 14, 2009 If you don't change the speedo gear, you cannot possibly calculate a correct mileage.I wish we could buy gas without Ethenol, but they put it in all gas now from what I understand. Ethenol definitely reduces MPG and causes damage to these older vehicles fuel systems. There are still a few stations that have non ethanol gas around here. Or at least they don't have stickers on the pumps :D . Actually I have done alcohol content tests on a couple and they were indeed alcohol free. I did notice in Fl that EVERY station had the "may contain" sticker. I was teaching how to test for alcohol content for fuel class. Had a gallon of 10% ethanol in a plastic fuel container. Started out at 10% for the first class. After 4 weeks in the can, the gas was barely registering any alcohol. Container always sealed and kept in temp controlled room of 70 degrees F. The alcohol was vaporizing and leaching vapors out of the plastic can. So, if you start with 10 gals of gasohol, let it sit in your truck for a couple of weeks, you will be down to about 9 gals. total fuel. That won't help the mileage! Gotta luv the govnmt. " We are from the govenment, and we are here to help" Link to comment Share on other sites More sharing options...
ComancheKid45 Posted January 14, 2009 Share Posted January 14, 2009 4.0 AW4 I usually get about 11-12 city and 15-16 hwy but I'm on 30x9.50 tires with 3.55 gears and the stock speedo gear so id imangine its alittle bit better than i calculate Link to comment Share on other sites More sharing options...
comanchedude Posted January 15, 2009 Share Posted January 15, 2009 89 Comanche 4.0 aw4 4x4 33" x 4.10 I get 17-18 combo best I do hwy is 20mpg ..and yes my speedometer is calibrated :) Link to comment Share on other sites More sharing options...
Car RamRod Posted January 15, 2009 Share Posted January 15, 2009 renix 4.0/5 speed/3.55s City I never really calculated. On the highway I've seen 24.5. This is at about 65mph. It really tanks if I go any faster. I still have to change to new injectors, get an alignment, and go for another run to see what I can get. Link to comment Share on other sites More sharing options...
carnuck Posted January 17, 2009 Share Posted January 17, 2009 18 mpg average '88 MJ with 4.0L, BA 10/5, D35/D30 3.73 with 33/9.50/15s (not 4x4 though. Finally have an AW4 with NP242 hooked up and hopefully runing within a few more weeks) Link to comment Share on other sites More sharing options...
flint54 Posted January 17, 2009 Share Posted January 17, 2009 92 Eliminator, 5spd, 4wd, <60K miles, completely stock: best on interstate @65-70mph = 23 mpg typical mixed driving = 18 mpg Link to comment Share on other sites More sharing options...
voltageyz0 Posted January 17, 2009 Share Posted January 17, 2009 i think somthing is wrong with my truck becausse the last few times i filled it up i have been getting 8 mpg Link to comment Share on other sites More sharing options...
JeepcoMJ Posted January 17, 2009 Share Posted January 17, 2009 If you don't change the speedo gear, you cannot possibly calculate a correct mileage. mathematics my friend. if your speedometer is off you can figure out how far it's off fairly easily. I don't recall the equation right now, but hopefully geonovast the mathematical wizard will figure it out. now, the easiest way to figure it (my way) is to plug the gps in, flip it to show the little mph reading, and drive. my 87 is off by 1.5 mph. the 3800 is off by something like 13%. so, at 13% multiplied times normal miles per tank which is 380 = (49.4+380) which = (429.4/gallons which is 16gal) = 26.8375 the 87 I get basically 17 to 21 with it varying. well, that was before the swap to High Output so we'll see. Link to comment Share on other sites More sharing options...
1990 Pioneer 4x4 Posted January 17, 2009 Share Posted January 17, 2009 Not good but who cares, it's not my DD. Link to comment Share on other sites More sharing options...
89mjpioneer Posted January 18, 2009 Share Posted January 18, 2009 89 mj, 3.07, BA-10, 3in lift, 31s and a inacurate speedo I get about 18. I know it should be higher because on the highway my speedo says 65 but I'm really doing 80. Link to comment Share on other sites More sharing options...
SoloCamo Posted January 18, 2009 Share Posted January 18, 2009 Around 13-15mpg around town...and on strictly highway I've seen 20-21mpg. '88 4.0 Auto 2wd I average around 16mpg though, as most of my driving is in town and short trips. :doh: Link to comment Share on other sites More sharing options...
carnuck Posted January 19, 2009 Share Posted January 19, 2009 i think somthing is wrong with my truck becausse the last few times i filled it up i have been getting 8 mpg Either quit driving around in low range or watch out for that neighborhood kid with the hose you have hanging around! :dunno: Actually, the coolant temp sensor (one screwed into the block for the computer and not the one in the head for the gauge) will give hideous fuel mileage if it's bad. Link to comment Share on other sites More sharing options...
mvusse Posted January 19, 2009 Share Posted January 19, 2009 Coolant temp sensor is usually the culprit, but a bad O2 sensor has the exact same effect: computer running in open loop. Link to comment Share on other sites More sharing options...
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