Monster88

I have a 1990 Jeep Cherokee 4x4 with the Straight 6. Can anyone help me find a inexpensive way to up my mpg and performance? Maybe give me tips on how to help improve those things?

Also i have this noise that sounds like its coming from the front end but its not a constant sound. It only happens when I'm in drive and rolling but only when I'm pressing on the gas, otherwise when i let off it goes away. Can anyone let me know if you have or had the same problem and/or if you can tell me what i can do to fix it?

crumpmanjr

this section is for builds!

Lead Foot

And use the search option. Been covered many times.

Lead Foot

I will help you with the front end though. When you are in 4wd? Sounds like bad gears.

Monster88

no 2wd. havent really had the chance to try the 4wd. =[

Radi

What are you getting for gas mileage now? Probably one set of things to do to get it up to stock level and another to get it up beyond that.

Describe the noise? Grind? Squeak? Clunk? Someone whistling the theme from "Oklahoma"?

XcherokeeJ

For some hp I would recommend an exhaust, bigger fuel injectors(I am about to put in some that came off of a Ford Mustang - Ford #19 I believe), and a hotter spark to match the spray. Some people may think about getting intake upgrades, I am one of them, and others think they are pointless. As for the noise, I am no help for you.

Height Rider

i would say for gas mileage keep all fluids up to date, cold intake, cleaners (gunk over the years) good spark plugs, and keeping it around 55-60 helps too... as for the noise i had the same problem.... turns out after i sank my xj water got in the differential and turned my fluid into almost a putty... so thats where you should start...

salad

Really depends on what mileage and running condition you get right now. Plenty of threads for increasing fuel economy on a stock XJ. But if you have really bad blowby that's another story... Snorkle cant reseal your rings

cruiser54

Plugs, wires, cap and rotor. Fuel filter. Clean the throttle body and IAC. All this first.

91 limited owner

inexpensive way to up my mpg

car5car

wrong about injectors and spark plugs

xjheep92

That's what I did lol. Except mines a trail bike that I made street legal.

As far as the jeep goes:
cowl intake, new air filter, 703 injectors, bored out throttle body, relocate the air temp sensor to the air box, new spark plugs, wires, cap and rotor, apn header, newer style 97+ intake header, free flowing exhaust, keep stuff off the roof and take any extra weight out of the jeep

Red82

Not if you have old, worn out, dirty injectors and spark plugs. They may not gain more hp than stock but it would be more than they are currently getting. It'll also help mpgs to have clean fuel injectors and fresh spark plugs (as well as all the other tune up items.)

F1Addict

The injector myth is just that, a myth. There are definitely advantages to installing the 703s, they're more reliable, they're more efficient because they produce a much more useable spray pattern that increases combustion efficiency but they won't noticeably improve horsepower or fuel economy above stock. One thing they will do (and that's why I swapped mine) is prevent fuel leaks around the injector body, something the stock injectors are notorious for.

Listen to Cruiser, give it a thorough tune up, check your tire pressures, and take it easy on the long, skinny pedal. If you're lifted with big tires, make sure you're geared correctly, check for exhaust and vacuum leaks, clean your throttle body. Also, remove all nonessential stuff from inside, weight is the enemy of fuel economy and performance. Good luck.