Bad gas milage 1995 montero sr

[Monteroguy]

Alright so i bought my rig stock with 30inch tires, the very best gas milage i got was 16-17mpg on the flattest part of I-5. Everywhere else i was getting 12 or so on a good day, mind you for the few weeks that i tested this i was driving like a grandma. Now i have 305/70r17 (34") and an A.D.D bl. I did cut the muffler off and replace it with a cheap little cherry bomb. Now, my mpg is around 9-10 it sucks cause i drive everyday and its so bad i am almost considering selling it. Any help is appreciated. I am aware that it may just be the way of the game for v6s and big tires haha.

 

[jeep-N-montero]

Ha ha, are you really that surprised?

 

[SD_Montero]

It sounds like something isn't right honestly. I have 31s with the 3.0 and get at least 18 mpg combined.

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[Swank Force One]

The best i've ever done on my 98 is 18.2mpg. Usually around 14-15mpg, 33" tires, 2" body lift, flat land driving, and i drive Miss Daisy.

It's just not going to get good gas mileage. If you baseline the truck well, might get another couple mpg out of it.

 

[mtnblue]

I just bought a 95 SR with 31's and the first tank I filled with supreme, and I got 24 mpg (I checked my calc's twice- I couldn't believe it). With plus on the 2nd tank I got 20+ mpg in mountain driving above 6000'.

 

[Monteroguy]

Not that much, i might just get a honda civic as a second car haha. But in theory having the larger tires means my cruising rpm is going to be a lot less so if i accelerate slowly up to speed i SHOULD be getting better mpg everywhere.

 

[Monteroguy]

Yeah, i was hoping something was wrong so i could fix it and solve the problem haha. My check engine light comes on every once in a while so maybe an o2 is out.

 

[kalieracer]

dead 02s can cause worse mileage

Yeah, i was hoping something was wrong so i could fix it and solve the problem haha. My check engine light comes on every once in a while so maybe an o2 is out.

 

[plh]

But in theory having the larger tires means my cruising rpm is going to be a lot less so if i accelerate slowly up to speed i SHOULD be getting better mpg everywhere.

unless you have moved the engine out of the power band. Plus you are humping around a lot more tire weight, rolling resistance and have raised your rolling brick higher in the air for more air resistance.

 

[Earlron]

Are you using your speedometer for MPG calcs?

 

[Earlron]

If so try a speedo calibration

SPEEDO GEAR Dealer parts:
MD705466 - Gear, Speedometer Drive (N=26): For 4.625 gearing and stock (225/235) tires
MD705464 - Gear, Speedometer Drive (N=24): For 4.625 gearing and 31" tires
MD705463 - Gear, Speedometer Drive (N=23): For 4.625 gearing and 32" tires
MD705462 - Gear, Speedometer Drive (N=22): For 4.625 gearing and 33" tires
MD705461 - Gear, Speedometer Drive (N=21): For 4.625 gearing and 35" tires
MF472536 - Spring Pin, Speedometer Drive Gear (3x16mm)
MD701788 - O-ring, Speedometer Drive Gear (10.3mm)
MF520403 - O-ring, Speedometer Drive Gear Casing (35mm)

 

[Swank Force One]

The best i've ever done on my 98 is 18.2mpg. Usually around 14-15mpg, 33" tires, 2" body lift, flat land driving, and i drive Miss Daisy.

It's just not going to get good gas mileage. If you baseline the truck well, might get another couple mpg out of it.

Yeah, i was hoping something was wrong so i could fix it and solve the problem haha. My check engine light comes on every once in a while so maybe an o2 is out.

Yep.

Fix your truck.

Then re-evaluate.

 

[Monteroguy]

Are you using your speedometer for MPG calcs?

Sort of, i know that it would be right if i had 30 inch tires so i just divide 1.12 by what i have on my trip meter.

 

[Monteroguy]

dead 02s can cause worse mileage

The 1995 is obd1 right? I remember taking it to a pepboys to test it and it wouldnt connect. At the moment i dont have any lights on my dash ( usually its an alternating christmas tree).