Ol' Green

After lifting my 98' xj 3.5 inches i got some very noticeable vibes. A tc drop kit helped a little, but the vibes are persistent. Anyway, I'm curious if drive line vibrations affect MPG. Because right now I'm getting around 8 mpg and I drive mostly in the city...

JeepaholicNinja

Lol I have driveline vibes on medium-hard takeoffs from complete stops...Really bad ones...My friend thought the tires were hitting the fenders when he felt/heard the vibes...I'm stock saggy height though, but just incase it helps, I figure with a 20 gallon tank, and 8 little white "tick marks" on the fuel gauge, each mark is approximately 2.5 gallons. On regular gas, I get 25-30 miles per tick mark, so about 10 mpg or so. This is stock suspension, 225/75/r16 tires (Pretty much designed for roads), stock 16" wheels, BUT I have a THULE roof rack, and ON TOP OF THAT I have ski racks...Also, I'm not sure how much driveline vibes are a part of my equation, since they only last a few seconds at a time, but my point is...an XJ has bad gas mileage...What size tires do you have?

Tsaani97xj

I am afraid you have a bigger problem. Although driveline vibes caused by incorrect angles and minor binding could theoretically cause a minor decrease in mpg, due to extra resistance while accelerating, it would not be significant. I have driveline issues from my lift and no SYE but still get 14-17 on 31s and 3.07 gears.

salad

First off do a tuneup. Then start looking at the thousand billion threads on poor MPG (most of which start with tuneups).

The lot of you need to replace your U joints and get your tires balanced

sycoglitch

Second, lifting a vehicle messes with the MPG due to aerodynamics and such. Welcome to the jeep world

SteveMongr

Yea, what they said. But what it does affect (and wear out) is u-joints, pinion bearings/seals, output shaft seals, motor/transmission mounts, etc...

Dumajones

This ^^^^^^^^

andrewmp6

A lift and bigger tires will hurt your mpg and the winter gas will do it too.What size tires are you running?

Ol' Green

Not sure of the exact size, but they're stock.

sycoglitch

Once a vehicle is lifted, bumpers changed etc, mpg suffer. That's all there is too it. If mpg is a factor then drive a prius. There are ways to get mpg back but thats after regearing and such later on

Ol' Green

Hell, if I can get around 15 I'll be happy as can be.

Ol' Green

Just a little update here. Ive flushed engine and tranny oil, and then replaced with synthetic. Changed the diff oil while I was at it. Then did a tune up (spark plugs, wires, cap, and rotor). Now I'm getting almost 16 mpg! Doubled from the 8 I has getting. I didn't think a tune up and oil changes would help that much but I'm glad i was wrong. Thanks for all the help guys.