Looking for some troubleshooting assistance here. The last 2 tanks of gas I've averaged 11mpg in my 07 JKR w. 4.88's, 37's & 6 SPD manual. This driving was 60% highway at 70mph and 40% city. Prior to this, the jeep sat for 3 months while I was adding PSC fenders and swapping in a prorock on the weekends.
I was averaging closer to 17 the last few times out and 13 pulling my 1500# camper!

I have noticed a couple odd things:
-Even when I keep the pedal steady on the freeway trying to maintain speed, the Jeep lightly surges as if cruise control is on.
-Sometimes when I let off the pedal and take the Jeep out of gear, the engine runs on at about 2k rpms for a few seconds without dropping rpms.

Not sure how this relates, but when the Jeep gets really hot (wheeling in 4LO in 95*+ weather with the AC on) I can smell fuel outside the Jeep in the rear as if I have a vapor leak. This issue predates the RIPP, I cannot find any loose or damaged lines to the evap and the gas cap passed inspection....

 

A lot of fuel economy related issues with the 3.8L that I've seen are the O2 sensors and the CATs. If the O2 sensor is failing the computer will want to run rich. Just replace them all for easy preventative maintenance. If your cats are plugged that is a whole different ball game.

 

Thanks Smudge! I am wondering also if a boost/vacuum leak would contribute to this... Has anyone had the fuel vapor issue I am having?

 

Is it possible to test the O2 Sensors possibly for resistance to see if they are bad? I am not getting any CEL's indicating bad sensors. @RIPP can you chime in on possible trouble shooting advice?