Good evening everyone, I've recently noticed a drastic change in my Jeeps gas mileage from around 15mpg to now 9-10mpg. I'm pretty good at keeping up with the maintenance (no check engine lights), and I know my lift & 35" tires don't help but I've had those modifications on for the past 4 years I've owned my Jeep. I checked all my oil levels and they are just over full and still clean. I cleaned my air filter, and even tried adding some Lucas to my fuel to see if that'd help but doesn't seem to of had any effect.
From my recent research I'm seeing there is a chance it could be from a cracked Exhaust Manifold fooling the O2 sensor making it run rich. I've done some visual inspections and haven't found anything that looks like a crack, although it's hard because of how much old mud has been caked up on the pipes. it looks like I have aftermarket exhaust manifold from what I could see but I'm not sure when it was installed as my previous owner had to have done it.
Also my jeep does have a bit of a ticking sound while cold, not sure if that's also a sign of a crack?
As for my methods of testing fuel mileage, it's about 60 miles to the mountains from my house so I'll usually fill up before I go wheeling and reset the odometer once full. Then I will hit the last gas station before my turn off for the trails and do a quick calculation of the miles driven. I'll do the same thing for the ride back as most of the drive is on the interstate (I try to keep it under 65mph which is about 2400rpm).
What are your guys's thoughts for the sudden drop in mpg? Thanks for your time!
From my recent research I'm seeing there is a chance it could be from a cracked Exhaust Manifold fooling the O2 sensor making it run rich. I've done some visual inspections and haven't found anything that looks like a crack, although it's hard because of how much old mud has been caked up on the pipes. it looks like I have aftermarket exhaust manifold from what I could see but I'm not sure when it was installed as my previous owner had to have done it.
Also my jeep does have a bit of a ticking sound while cold, not sure if that's also a sign of a crack?
As for my methods of testing fuel mileage, it's about 60 miles to the mountains from my house so I'll usually fill up before I go wheeling and reset the odometer once full. Then I will hit the last gas station before my turn off for the trails and do a quick calculation of the miles driven. I'll do the same thing for the ride back as most of the drive is on the interstate (I try to keep it under 65mph which is about 2400rpm).
What are your guys's thoughts for the sudden drop in mpg? Thanks for your time!