TRCM

sounds like a winner......not all tires measure the same when you do that....

ClydesdaleKevin

My 40 tooth speedo gear came in from Quadratec today (with a new o-ring), so I installed it this morning in no time. Great instructions from Quadratec! I changed out the 4X4 indicator switch while I was at it (brand new on eBay, 11 bucks w/ free shipping, using the Dorman part number in the search window). Then I took it into town, topped off the gas, and reset the trip meter. NOW I'll be able to get an accurate assessment of my MPG. The speedometer definitely reads differently than it before compared to my perceived speed...and where I thought I was comfortable driving at what the speedo said was 55mph, it looks like I was driving around 48mph...because that is still the sweet spot for the way I like to drive on back country roads with the new speedometer reading. Shifting seems smoother and more predictable as well. I will update this thread next week with an accurate MPG calculation. Thanks for all the help guys!!!

Kev

ClydesdaleKevin

Update! I topped off the tank today for the first time since changing the speedo gear. 151.5 miles since the last fill up (right after changing the gear). 10.7 gallons to fill the tank. So that comes out to 14.12 MPG...which sounds more reasonable.

Will not having my O2 sensors hooked up decrease my MPG? The PO never hooked them up.

Kev

Tbone289

It should definitely be better with operating O2 sensors. You're likely running pretty rich.

Between this and removal of the airbag and everything else, it seems the PO was a real piece of work! lol

ClydesdaleKevin

LOL! Nice kid...but he was a kid, late 20s I'm guessing. At least he had his head on straight and works hard supporting a family.

I read that elsewhere, that it will run rich without the O2 sensors...so as soon as I can, I will be changing the whole exhaust system out with something a lot more efficient and quieter, and change out the O2 sensors while I am at it. I am also going to add a full flow cat (no cat in this PO exhaust). Even though my registered state of Florida doesn't require it, I'll do my part to reduce emissions...and get a little bit more low end torque while I am at it).

Kev

ClydesdaleKevin

Okay, another MPG update: I topped off today after driving 178.5 miles. It took exactly 11.5 gallons to fill, which comes out to 15.5 MPG. I'll take it! WAY better than my old 85 K5 Blazer was getting! Next week I'll do the math again and average all three numbers out. Once I do the exhaust and change out the 02 sensors (which probably won't happen until winter in Arizona), I'll do some final updates to see if I get any increase.

Kev

Tbone289

That MPG is in line with what I would expect from your setup (lift, tires, gearing, etc.). I hope the 02 sensors actually improve that, but I wouldn't expect it to get much better.

What kind of driving made up that 178.5 miles you drove?

ClydesdaleKevin

All back roads, with top speed of around 50mph, and average speed around 45mph.

Kev

Tbone289

Ah, OK, so that's as good as it can get for MPG. You probably will see an improvement with the O2 sensors then.

ClydesdaleKevin

Yep. I don't like driving fast, so I avoid highways and take in the scenery. 40-45 mph is my favorite speed to drive. My wife says I drive like a little old lady...lol!

Kev

Tbone289

I prefer the scenery as well, but luckily my old lady does too. 2-lane has a more "fitting" pace for an XJ, IMO! I can get into the 22MPG range at 55-60, but mine is pretty much stock.

ClydesdaleKevin

Nice! I'm happy getting 15 in my lifted XJ with 33s. I was only getting about 7mpg in the K5 with a lift and the same size tires. And that was with a perfect tune up and sane driving habits. I never could figure out why it got almost as bad gas mileage as our RV with a carbureted 454...lol!

Kev

Tbone289

WOW. Yeah, I bet you're pleased to double our fuel mileage. I have a '67 Bronco on 31's and it gets about 16 at 60MPH w/the original motor. Not bad at all, but I have a current-gen Ford Focus at gets 38. Once you get used to that, the XJ and Bronco seem pretty bad.

It's all relative, I guess!