2021 Jeep Gladiator Diesel 3.0 horrible MPG

[my dog Trigger]

2021 Jeep Gladiator diesel on 37's getting 13-14mpg in city driving. wondering if there are issues anyone knows could be causing. drives fine. no issues as i know it, aside from tiny gas tank, reported fuel mpg is horrible.

i was getting 22 to 27 mpg then fuel system crashed in march 65 days to repair when i got it back milage dropped to 16 to 22 y81 recall for def gets you about 4000 mi per tank, better than what it was getting before . Ive installed a skull krushers throttle controller went off road 19.5 mpg getting around 25 mpg on freeway with 37 inch tires ,still not what it was before ,wish i could find a good mechanic who under stood this engine these dealers in california don't have a clue!

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[Pescatoral Pursuit]

My 21 JTRD on 37s was getting horrible ~16mpgs (calibrated and hand calculated) and switching back to the factory tires didn't seem to help. It was to the point I was considering ordering another one. Not long after that I noticed the mileage going up and correlated it to not having idled in park for the last few tankfuls. Now averaging low 19s (which is still way too low imo) but a lot better. I don't know if it's the fuel consumption in park or an increase in regens because of it (not that I've noticed a fluctuation in def usage.)
Something to consider.

Sweet Gladiator!!!

Someone loves their Hooke Roads!

 

[Koolcarguy]

My 21 JTRD on 37s was getting horrible ~16mpgs (calibrated and hand calculated) and switching back to the factory tires didn't seem to help. It was to the point I was considering ordering another one. Not long after that I noticed the mileage going up and correlated it to not having idled in park for the last few tankfuls. Now averaging low 19s (which is still way too low imo) but a lot better. I don't know if it's the fuel consumption in park or an increase in regens because of it (not that I've noticed a fluctuation in def usage.)
Something to consider.


Someone loves their Hooke Roads!

I do they seem to hold up to some abuse and they don't bankrupt you lol

 

[caryw5150]

i was getting 22 to 27 mpg then fuel system crashed in march 65 days to repair when i got it back milage dropped to 16 to 22 y81 recall for def gets you about 4000 mi per tank, better than what it was getting before . Ive installed a skull krushers throttle controller went off road 19.5 mpg getting around 25 mpg on freeway with 37 inch tires ,still not what it was before ,wish i could find a good mechanic who under stood this engine these dealers in california don't have a clue!

banging ride.... thanks for the time to reply. and thanks to everyone for adding some useful tips.

 

[caryw5150]

My 21 JTRD on 37s was getting horrible ~16mpgs (calibrated and hand calculated) and switching back to the factory tires didn't seem to help. It was to the point I was considering ordering another one. Not long after that I noticed the mileage going up and correlated it to not having idled in park for the last few tankfuls. Now averaging low 19s (which is still way too low imo) but a lot better. I don't know if it's the fuel consumption in park or an increase in regens because of it (not that I've noticed a fluctuation in def usage.)
Something to consider.


Someone loves their Hooke Roads!

loving the jeep. hating the tiny tank and fuel MPG but i'm gonna crack it. i'm waiting to calibrate the speedo then try some other tweaks. if i read it right this ain't normal and yeah the best effort you'll get is from the work you do yourself.

 

[@californiajeeping]

loving the jeep. hating the tiny tank and fuel MPG but i'm gonna crack it. i'm waiting to calibrate the speedo then try some other tweaks. if i read it right this ain't normal and yeah the best effort you'll get is from the work you do yourself.

Your large wheels dont help they are very heavy and wide. Getting a 17" wheel with less offset and width would help quite a bit too by being lighter. Just FYI.

 

[Pescatoral Pursuit]

I do they seem to hold up to some abuse and they don't bankrupt you lol

I've been on the fence forever between these and the rock hard Patriots.

 

[Teqsand]

If you're speedo was reset, then try a JSCAN on it and look for the EGT VVT codes.....

Mine came direcrly from the mother ship with a bad EGT harness, wouldn't pass smog from day 1 and the MPG we like yours on stock tires....

 

[Burghardphotography]

bringing this thread back from the dead, as now I have my 3.5 in lift and 37s on. Picked one of the lighter wheel and tire combos I could get. I’m on my first road trip on these tires, and I’m not all too impressed. As a stock JTRD I was getting 23-26 mpg Highway depending on how hard I drove it. Today on the 37’s on mostly flat ground I’m averaging 19 mpg with cruise control set at 65. Alignment was checked yesterday, I run an ounce of hotshots per tank, and Speedo is calibrated with an AEV pro cal. Trucks not overloaded, just winch, rack, tent, and two 230 lbs humans.

I’m having a hard time now supporting the crowd that says you don’t need to regear the diesel for 37’s. Maybe I’m just expecting too much.. don’t know

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