Gas and O2 issues when traveling across the country.

[90volts]

Hey everyone. So just got back from our cross country trip. Went through PA, OH, IN, IL, MO, KS, and Ok with no problems. I started to run into issues in TX. Engine light came on and gave an O2 sensor code. Worried me , so cleared it and tentatively went back into the road. Two days later it came on again. Same .. O2 sensor. So we had that problem in TX, NM, AZ, CA. About every other day the light would come on and go back off after a couple / few hundred miles. Same things going back through AZ, NM, and TX. It stopped doing it in LA, and we had no problems since. Our path was LA, MS, TN, VA, DE and back to PA. It’s been a week mow in PA and still no issues.
Related? also .. not happy with our average mpg which turned out to be 14.5 mpg! We were loaded up so maybe that can explain some of it but seems excessively low.

Also... Out West I had some real problems with RPM and keeping up speed. I pretty much stayed at 65 while the light was on. Not by choice... just seemed I couldn’t get any faster without really winding up the engine. I would actually have to speed up to about 4500 RPM and then let my foot off quickly to force the shift to a higher gear, and then foot back on the pedal to keep up speed. Only through those western states was this a problem.

Anyone else have an experience like this? Any suggestions?
2015 Jeep Sahara jku. 33 inch tires and 2.5 lift. Unfortunately, stick 3:21 gears. I know that needs to be upped for highway travel now.

Any ideas would be appreciated. Thanks!

 

[NorCalRam]

Depends on the O2 code. Pre or post cat? Pre cat determines A/F is accurate, post determines if cat is working. Most any vehicle made recently will be able to deal with any fuel octane level if that is a concern.

 

[90volts]

Why got me was that it only happened in one part of the country. I’ve never had a problem near home, or once I got to Louisiana all the way home. Nothing was changed with the Jeep , so why only then? Made no sense to me as a physical failure so figured it had to be something local. I plan on having the dealer check it out sometime soon. (Still under warranty).
Thanks.

These are two codes I looked up. After that I started to just clear and keep going.

“P0420 Code: Catalyst System Efficiency Below Threshold (Bank 1)


What the P0171 code means. The P0171 code means that, on the first bank of the engine, the fuel system is running weak or a vacuum leak exists near this side of the engine. A lean condition occurs when the engine either receives too little fuel or too much air.

 

[NorCalRam]

P0420 means the cat isn’t working. The lean code could be due to a vacuum leak after the airflow sensor, dead misfire, possibly weak injector. Misfire would have set another DTC though but could lead to a bad cat. Any drivability concerns? Any recent vehicle service?

 

[old_man]

My bet is on the cat

 

[90volts]

P0420 means the cat isn’t working. The lean code could be due to a vacuum leak after the airflow sensor, dead misfire, possibly weak injector. Misfire would have set another DTC though but could lead to a bad cat. Any drivability concerns? Any recent vehicle service?

During the drive when the light was on it seemed to be really hard to keep the RPMs where they needed to be. I was constantly having to speed up and let off the gas to force it to shift to the next gear. otherwise it would wind up to 4500/5k before even thinking about shifting on its own. And now that we are back home for a couple of weeks now i have not had a single issue with shifting or an engine light. Thats why i though gas or environment. The jeep had just been inspected (safety and emission) a week before leaving, along with an oil change. No recent work other than that. Not since i have had it (over a year) other than axel seals , and 4x4 service (diffs and transfer case) months before we left. I havent taken it in yet to get checked out by the dealer. Ill find the time, and let you know what i hear. thanks for the input!

 

[NorCalRam]

Bad gas is super rare but I guess it can happen, the computer should be able to adjust for most any environmental changes. Sounds like misfire or even clogged cat/exhaust, totally insane that it just went away! I'd be interested to learn more.

 

[USStrongman]

I'm betting you stopped at shitty fuel joints in Texas going west. Fuel quality makes a huge difference in my JKU. I just did 1700 miles from West Texas to W NM, Durango, Ouray, Telluride, Montrose, Moab, Pagosa Springs and back. 40 miles and a few days after returning I had a clogged injector at 58,000 miles. I stopped at Loves Truck Stop last. Shit fuel. Plus, in the Rockies and Arizona, they have changed to winter fuel which has a slightly lower (~1.7%) less efficient evap rate giving you a less efficient running motor.

In addition, the wind blows a lot in most of TX, NM, AZ. 3.21 gears and bigger than OEM tires suck the power right out of these rigs. The heavier wheel/tire combo and it can be absolute shit. I run 91lb combo weight wheels and tires with 3.73 gears. It isnt optimal at over 60mph with my JKU fully loaded and its heavy empty. (AEV bumpers, skids, roof rack, heavy tire carrier/hinge, steps). Depending on the weight of your rig when full of gear, fuel and how its equipped, 4.58 to 5.13 are common. Pulling a trailer? 4.88 or 5.13 will help a ton on the freeway.

What Is The Best Jeep Gear Ratio When Adding Larger Tires?

Matching the proper axle ring and pinion ratio to a larger tire size is a cost-effective way to make up for lost power and performance.

www.quadratec.com