Hey guys, the jeep has been recently getting what seems to be horrible gas mileage. I never really fill it up all the way due to gas prices but I put a little over a half a tank in and within 4 days it tells me I need gas. My cat converter is gone and I know it because it rattles badly, and the exhaust mani is cracked. The O2 sensor is original by its looks. After driving occasionally I will get a strong smell of gas outside the car after its shut off. It does take some time to start intermittently like a bad check valve in the pump. I also am thinking my gauge just could be messed up. Any help its appreciated! Thanks

 

Every single thing you mentioned will adversely affect your fuel mileage. It sounds like you're running very rich... replace your cracked manifold, cat, and O2 sensors and do a tune-up including air and fuel filters, plugs, cap, rotor. Clean your throttle body, check for vacuum leaks. Not only will you get better mileage but your rig will run a lot better.

 

Thanks for the reply. Im gonna order a manifold tonight and pick up an O2 sensor. I recently changed the plugs, wires, cap, rotor, air filter. Havent done the fuel filter but will do soon.

 

I've read that the cracked exhaust manifold has a pretty significant impact on fuel mileage because it affects the exhaust gasses in a way that fools the downstream O2 sensors which control mixture. Given that you've done a lot of the other routine maintenance things, you should see some noticeable improvement with a new manifold and O2 sensors.

Let us know how it goes.

 

I hope there is some improvement. Recently its sluggish on taking off and seems to just have sporadic issues that ive read point to bad O2s .

 

This.

You have some work to do. Gotta keep up with this stuff.

 

Yes I do. This all started to become an issue within the past few weeks so I hope it all will return to normal once I replace the parts.

 

I filled the jeep all the way up tonight because my light was on and it was showing on E. It only took 15.5 gallons to fill it up. Is my gauge off and thats whats making me think bad milage? I know I need to do the exhaust repairs and I will do them but is this also something worth figuring out?

 

Never calculate gas mileage by how many miles you go on a tank.

Do the math. Miles driven divided by gallons consumed.

Get at least 3 samples before coming to any conclusion.

I keep a small notebook in my glovebox and every once in a while, I take a gas mileage reading to make sure the XJ is running efficiently.

 

When I fill up my 95 country, it typically takes about 18 gal's. (Since the light comes on with just under 1/4 tank indicated, I usually drive about 30 miles with the light on before filling up.)

Did u fill up immediately when the light came on? If so, your 15.5 gals to fill up sounds about right.

 

No I probably ran a day or 2 with the light. There have been times I've driven a week with the light on and never had any issues and probably drove 40 miles or more with the light.

 

How many miles per gallon is considered "bad"?

 

Sorry, Im really new to this and just got my 98 Cherokee Sport and im only getting 13 mpg and I baby the accelerator. Could you explain what you mean by plugs, wires, cap, rotor, coil? Im just kinda confused and I want to tune it up to see if that helps!

thanks

 

Job #1 for you is to get yourself a service manual. That will explain things in detail that we can't get into here. Haynes and Chiltons manuals available at many parts stores are OK, but the Factory Service Manual is the best.

Here is a link to a factory service manual for $7.95. It's digital, but a very good deal. If you want a hardcopy FSM, check ebay; they come up periodically.

http://www.pacificcoastmanuals.com/j...e_manuals.html

 

What would you say is the best Plugs to put in the 4.0?