johnj92131 Posted July 24, 2016 Share Posted July 24, 2016 Just finished driving the Comanche from San Diego to Boston and had no problems along the way. My MPG varied quite a bit, depending on the speed I was driving and other things. But by the time I reached Springfield Ohio, I decided to see what would happen when I tried to drive for max MPG. My route was right along Interstate 90E. Tried to keep the speed down to 55-60 range, but sometimes it got up to 65. Anyway, by my truck odometer it was 517.4 miles and I used 20.0002 gallons of gas (Yes, 20.0002). I filled the tank the same way each time for the trip. Let the gas pump shut off automatically, then add more gas till it shut off again. Anyway, that tank works out to 25.8697 mpg for that tank. My previous best mpg attempt was just over 23 mpg Other tanks along the way ranged from a low of 16.30 mpg (high speed driving) to 20.85 mpg with the first tank of the trip. Truck is a 91, AW4 automatic with H.O. engine. And yes, I ran the A/C the whole way across the country. Tires are 225/75 x 15 Today I am starting the trip back home and plan on making some side trips along the way. First will be along Skyline Drive and the Blue Ridge Parkway starting on Monday. Any suggestion from there on are welcome. Link to comment Share on other sites More sharing options...
Jargon Posted July 24, 2016 Share Posted July 24, 2016 Cool info. Thanks for sharing. Link to comment Share on other sites More sharing options...
AeroNautical Posted July 24, 2016 Share Posted July 24, 2016 That's impressive, I struggle for 17 highway, but I know some of that loss is from 33s and 4.56 gears. Wind resistance is a... pain. Link to comment Share on other sites More sharing options...
daking Posted July 24, 2016 Share Posted July 24, 2016 That is impressive. That anyone would drive a Comanche across the country. When I need to drive more then ~100Mi, I have a support truck follow, or I use my massive trailer. And, my WHOLE drive train is new on my MJ. You, sir, are a hero... :) That GPM is impressive too. Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 25, 2016 Share Posted July 25, 2016 Yes, the sheer distance is very impressive John. Plus the MPG of course. I have never been on a trip that long with my 91. The most I've done is a couple of runs to Boston and back from Bama, and averaged just over 23 MPG with the stroker cruising at 65-70 MPH w. 31's and 4.10's. I was pleasantly surprised and happy with that since 14 MPG is about what I average around town. And have never squeezed any more than 19 gallons in my 23.5 gal. tank either. But I'm not really surprised with your results since it's an HO. :thumbsup: Link to comment Share on other sites More sharing options...
krustyballer16 Posted July 25, 2016 Share Posted July 25, 2016 That's almost as good as my cummins, which we talked about. That's great! Not so great on my part but it happens. Indiana heat probably didn't treat you too well either. I'd like to know your mpg on the way home with the car, trailer and 200 lbs of bumper now! (John stopped in my neck of the woods in Indiana to pick up the bumper/swing arm tire carrier I built for him) (( great guy to talk to! Glad we met)) Link to comment Share on other sites More sharing options...
gogmorgo Posted July 25, 2016 Share Posted July 25, 2016 I'm going to say that the 25mpg runs were running downhill out of the mountains... I'm just jealous. Still haven't cracked 20mpg myself... maybe if there wasn't a massive magnet in my foot sucking it against the floor... Link to comment Share on other sites More sharing options...
johnj92131 Posted July 30, 2016 Author Share Posted July 30, 2016 Made it back home on Thursday. Had a check engine light on from Tucumcari, NM. It ran very poorly on the down hill run from Holbrook, AZ to Yuma AZ (a 5000 ft drop that should have given me great MPG) only got 17.64 mpg Seems the temporary repair on the exhaust manifold done last March(?) failed, so I was back in the lean burn mode. So I ordered a new exhaust manifold and oxygen sensor from Amazon on Friday. Should be here on Sunday. Also ordered a fresh set of Bosch 703 injectors from Ebay, those arrive mid week. Except for that problem, the truck ran great all the way home. MPG ranged from 19.43 to 21.14, speed was above 70 for the most part. Don, That 23+ mpg you got from Boston back home is REALLY impressive with the stroker and the 4.10 rear end. Did get 1 ticket on the trip. 45 in a 25 zone in Shenandoah National Park. The ticket will cost me $180, if I mail it in quickly. Next trip in late August will be San Diego to Victoria, B.C. to get the 86 diesel MJ! Link to comment Share on other sites More sharing options...
schardein Posted August 1, 2016 Share Posted August 1, 2016 Glad you made it home safe and under your own power. I've owned several XJs and my one MJ, and I've been skeptical of claims of HO trucks getting over 20 mpg. I just got home from a 1300+ miles trip (Missouri to Camp Perry, Ohio for the National Rifle Championships) and averaged 21.6 mpg in my 91 XJ. Link to comment Share on other sites More sharing options...
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