Thanks for looking, sorry for another mileage thread...I have been reading around for weeks and troubleshooting with no luck. Any ideas would be appreciated, hoping maybe someone has been through this.
Purchased an 04 JGC V8 in August, was getting around 13-15 MPG, calculated by hand. In November I started noticing I was filling up a little sooner than usual, so I started keeping track. Week after week I was losing approximately 1MPG. Now one week to the next, I can understand a fluctuation, but this is crazy. Winter gas cannot be that much different and as I mentioned this wasnt a dropoff from 13 to 6, this got worse over time...From 11/20 I was getting 9.8 and over the last 8 weeks or so I am getting under 8. Have gotten as low as 5.75 and that week I was intentually babying the car. I have had about 3 stalls over the last two months and the truck has started right back up. I have done the fuel reg/filter 2x, first one WIX pushed 62 PSI, switched to Mopar, kicks around 57psi now. Plugs (champions), air filter, TB cleaning, IAC (mopar), BARRS headgasket sealer due to a slight coolant smell and some smoke, it did help that situation...O2 sensors done (mopar). Gas cap is the original, had aftermarket for a while and put original back as I understand that could have caused some problem...truck has new rad cap, new thermostat...TPS checked by me, backprobed, analog meter, smooth as it should be...I have tried fuel system cleaners, different gas stations, one of those compression oil additives...I am out of ideas.
If an alternator or battery is acting up, but not failing, could that cause this much of a drop in MPG?
New battery terminal connectors...
NO CEL light (and yes it does work).
A deep scan using Torque shows a non-monitored sytem check, 2 precat O2s switch a little slow, but fuel trims should make up for that (fuel trims are never out of whack)...I have also received a failed test on the purge system monitor due to an IAC shift, but cannot find any real information on that.
Also, did a vac test, stays smooth and steady at 18, drops, pops up and steadies out when reved, as it should.
Truck runs great, its still fast, no misfires, no sputters, I get a slight hesitation if going to WOT, thats it.
Some one stealing your gas when you are parked. Fuel leak somewhere. Injectors leaking (does it seem like you have gas in the oil?).
I have monitored the gas between leaving and getting back in day to day, does not appear that someone is stealing the gas...
I have not seen any leaks, have had it up on the lift and looked...Unless it's a pinhole and only happens at high pressure, I do not believe it's a leak.
No gas or coolant detected in the oil. Everything appears clean. Is there another way to check, any other signs if it were and would it essentially drop my mileage in half?
I also started to wonder if these AWD systems could bind up at all, essentially being in 4wd all the time...I do get some grab from time to time on turns at low speed, which to my understanding shouldnt happen...but, it does not "feel" like it's in 4wd all of the time. Quadratak 2
Im basically in the exact same boat and my issues started about the same time as yours. Ive also done all the same troubleshooting with all the same results. The only problem I know about is that my muffler is splitting at the seam with large holes. Cant imagine that would cause such a huge drop in mpgs though. Hopefully getting that replaced in the next week or two. Ill keep an eye on this thread and also let you know if I find out what my issue is.
2002 Overland - 4.7 HO, "Select-Drive", 4" RC long arms, TAG front winch bumper, 32" BFG KM's, 3" exhaust, Magnaflow hi-flow cat, Flowmaster 50 series
I've had my mechanic check for vac leaks as well as testing the vac...sowed nothing. I've read around and I think I'm going to try spraying everything with carb cleaner. Carefully. Manifold, evap lines, etc. we shall see. Maybe it's a small leak in the manifold. Maybe it's a bad injector, something getting a bad ground, who knows. Just can't wrap my head around it. I hope I did it at some point and when I do I plan in creating a things that effect mileage thread lol