OK Uncle, I need to improve mileage or sell the Jeep.

[fourplayoffroad]

i have a question for all of you i have an 87 with a 4.0L and auto trans i have a k&n pacesetter header NO CAT.CONVERTER flowmaster muffler 2 1/4 exhaust new o2 sensor new plugs new wires 4.56 gears 35x12.5 and 6.5 lift and im getting 12 in town and 15 on the hwy first off is not haveing a cat. gonna effect my gas millage and second if i do an msd 6al box and wires will i gain any mpg and further more will i notice any performance gains?

 

[Muddy Beast]

Shoot...reading this just made me hit myself.

I keep thinking "how the hell am I only getting 10MPH!?" But I realize now it's because I'm using the odometer on the Jeep after my lift and tires...and I KNOW my speeds off by about 5mph, so that explains it.

 

[winkosmosis]

With 32" it should be more than 5mph though. It's 18%. So when it says 60mph you're really going 71mph!!

Edit: NM, thought muddy beast was the OP

 

[Muddy Beast]

Double post...

^P.S. I meant 10MPG, not MPH.

 

[JACKED COUNTRY]

not having a cat will if anything improve your mileage,msd ignition and wires will increase mileage as well but if you look ok ebay you can find a jacobs omni ignition for less then half the price of the msd setup and it comes with a high output coil built in.

 

[winkosmosis]

Not having a cat will increase your emissions many many times

 

[Angus]

Just checking on my thread, great work guys. I have done the K&N, but my 2000 has a distributerless ignition so not much I can improve on there. My exhaust is stock so maybe work is needed there.

 

[chero-scrambler1]

I would almost just get some small street meats for daily driving and keep the big tires at home till I was headed to the trail... I am running toyo AT's during the week and 33" BFG MT's on the weekend. but I dont have specific #'s on milage though it is really just my weekend ride, and I am not done building it yet.

 

[emr1101]

get a manual. you can pretty much chose your gas mileage then....

 

[emr1101]

angus, with 32" ATs and 4.10 gears you should be getting better mileage, something is up. I think a tune up would be in order and do you know how to properly check mpgs?

 

[Kiefer316]

angus, with 32" ATs and 4.10 gears you should be getting better mileage, something is up. I think a tune up would be in order and do you know how to properly check mpgs?

X2 and are you sure your gettin that low of milage do a simple little tune up if you havn't done so...

 

[Angus]

The XJ is in good tune. It has new plugs and DIS ignition so no issues there. I keep up with everything else very well. The only question may be the injectors, but not because of an issue just they are 116,000 miles old. Even the O2 sensors are relatively new.

I have had the speedo checked with a radar, within a tenth of a mile per 10 miles.

Thanks

 

[fourplayoffroad]

i have another question my 87 also does not have the egr on it anymore the hole under the intake has been plugged (its air tight no leaks) will not haveing an egr mess with fuel millage??

 

[2001XJ-32]

emr1101; what manual are you talking about?

I'd love to choose my gas mileage...

Can any one recap the MPG techniques?

 

[Muddy Beast]

emr1101; what manual are you talking about?

I'd love to choose my gas mileage...

Can any one recap the MPG techniques?

One that tells you how to regear your speedometer/odometer? :dunno:

 

[farvaadm]

If your really into the jeep thing then it should be this big of a deal i'm a kid in high school making 7 an hour. i drive a 95 4.0 auto with 31s and a big roof rack 45 minutes one way to work getting like 15 and i make it work becuase i have a passion for the sport. if your so woried about mpg get a pinto!!!!

 

[N8s93XJ]

Check out gojeep.com. I think he used 3:73s with 31 inch tires and a modest lift -- around 4 inch -- and got close to stock mpg with some meatier tires. There was an earlier post/thread a month back or so that mentioned something about going over 3:73s and 31s you will see better mpg in 3rd gear because of the torque.

I run basically bone stock and consistantly break 20 mpg with synthetic fluids and Dueler Revo 28s... for daily drivin', I love the Duelers. (...and have a flat K&N filter with max-flow exhaust)

...I'm no mechanic.

 

[DeftwillP]

I think by manual, he meant Transmission.

 

[winkosmosis]

http://www.jeepforum.com/forum/showthread.php?t=571724

 

[Davinator61]

If you've EVER removed the intake/exhaust manifold combo, or the throttle body, you may want to check the security of their retaining nuts and bolts, as I've found these will loosen up over time, if not properly torqued down. You may also want to check to make sure your vacuum lines and fittings have no leaks, as these can also mess up your MPG, as well as cause driveability issues. Of course, you should invest in a good quality vacuum gauge, and learn how to use it to diagnose engine problems that would compromise MPG, as well as overall performance.