I know it's hard to argue with a dad but I have 186,000 miles, 3" lift, 31x10.50's and hundreds of pounds of bumpers, winch, and trail gear with 3.55's and average almost 18 mpg. You definitely got issues, I bet a full tuneup and new O2 sensors will do you a ton of good. Also replace your TPS, it can kill your mileage if it is not operating correctly.

 

I have them in my wifes wj 03 and no issues better performance and same mpg or little
better

 

cranesrule, how much do you think a full tuneup would cost? i've already done an oil change, air filter, priced out wires, plugs, and a cap. So far ill be about $70 down after the plugs and stuff. o2 sensors are i think $50 each, but im not sure. I don't know how much a TPS is, but i was actually thinking of cleaning out mine to see if that would help any. I just don't want to spend a lot because Im in the middle of looking for a job and living in a rural area doesn't leave many options.

 

$70 is worth getting 3-4x the MPGs, isn't it? You'll be paying more than that for a week's worth of gas until you get a job if you don't fix it right away.

 

The pricing you have seems about right. Replace your tuneup parts and see where you are. If you don't have at least 15 MPG at that point I would replace the TPS. You cannot clean it. It is about $35... If you still aren't there swap out the upstream O2 sensor. Don't worry about the one behind the cat.

 

Oh i know, filling up every 100 miles or less is starting to drain my funds. I'm not gonna wait much longer. It's time for a weekend camp out in my driveway surrounded by tools and a friend or two. I have a few ideas for some mods after a tune up

 

Sounds good! Let us know how it works out.

 

they helped in my dads ford f250 with a 7.5 (460). They picked up the fuel mileage a tad, and made it seem like it ran smoother.

 

I recently had some issues with rough idling, lack of power, and RPMs would just not go too high, no matter how far I pushed the pedal ( can't say exactly where they topped off, since I don't have a tach in my rig), not to mention I was filling up every week, 9 days max. Well, starting in November I began testing and switching out parts, all based on info on this forum (THANKS, EVERYBODY!) What made the bigger immediate difference was a throttle body clean up. I took it off, sprayed the HELL out of it, even cleaned the air filter box and air passage from this to the TB! Seafomed it, got marginal improvement til I replaced the TPS and the IAC. That made a WORLD OF DIFFERENCE! This is my DD, and now I'm refilling every 10-15 days depending on how many times I pull in overtime (I work weekends only! ) I should mention that I've been alternately running MMO and B12 Chemtool in the tank with a clean tank (no chemicals) between each treatment product so as not to mix them. My ride is veeery smooooth and responsive... Used to be I couldn't jam the pedal without leaving a cloudy trail of smoke behind me. No more...
I'm trying to say you should consider cleaning out your TB and replacing TPS and IAC as an investment, which you'll see returned once you stop spending as much money at the pump. IMHO...

 

im not going to read all comments but going to add that my freind had the plugs changed on her 4.0 zj at a shop a few years ago and said it never ran right again. I put champ coppers in and it runs great, it had bosch plats.

I also use champ coppers in mine and it loves them as well as recommended by the factory


definitally clean the iac and the throttle body all out, try some seafoam in the intake too, search on it...

 

Hey guys, I got a new cap and rotor and some new champion platinums because the coppers were out of stock. I already feel it running a lot smoother. The throttle response is better, it doesn't bog down as much when i punch it, and the vibrations at lower rpms are less. I didn't get new wires because they were still fairly good. Im gonna clean out the throttle body sometime this week and see how that goes. Possibly seafoam it after. Also, I heard that there is a coating on the inside of the gas tank and some cleaners can remove that. Should i be worried about putting cleaners in or is that just a myth?

 

Good job man. Don't worry about your tank, just use seafoam, Lucas fuel system cleaner, or chevron w/ techron in your tank and call it good. And if you don't know for sure how old those wires are, replace them. And oh yeah.... Get a set of coppers and replace those platinums. Just bring them back and exchange them, you'll probably get some coin back to put towards your wires.

 

X2!!!!!!!!

 

Don't worry about using a fuel system cleaner; it won't harm the gas tank.

BUT, there IS a coating on the throttle body. When you clean that, you want to use "throttle body cleaner", which is specifically designed for that task and won't harm your TB. Don't use carb cleaner for this job!

Either test those plug wires for resistance values, or replace them if they have more than 60k on them or if mileage is unknown. You can score a set for around $30. (no el-cheapo wires).

 

I might just stick with the platinums for now because I don't feel like workin on it in the cold this week and by the time I would get to them it would be too late to exchange. I already put them in and all the seals are crushed, I don't think they would take them back. In the summer I'll probably switch to copper plugs. The wires haven't been in there too long, but my dad and I are gonna test them anyway. They looked fine when I was workin. I remember my dad sayin theres a coating on the throttle body, so ill definitely get the right cleaner. Now that I know theres no coating in the tank, Im putting some cleaner in there. Anything else I should know? You guys are extremely helpful and I appreciate it