I have a 97 Cherokee and have finally gotten around to working on my motor. Got my 99 intake swapped in, 784 injectors, apn header, iat relocation, and an exhaust. The jeep doesnt seem to have good gas milage anymore after all these things that are supposed to help. The Jeep drives fine, no hesitations, cel's, re-flashed ecu and drove nice for a while to relearn computer. Seems like it wasnt as great of turnout as i had hoped.

 

Try solar panels on the roof

 

What mileage are you getting? I never understand the vagueness

I see you're running a 4 inch lift and 33s, have you regeared? XJs were never known for their fuel efficiency and with that rolling stock you should expect 12-14 mpg in the city and 18-20 on the highway even if things are in excellent running order and geared correctly. You're driving a raised brick with huge, heavy rubber donuts at the corners.

 

Sorry. I use to get around 15-16 being easy on the skinny and now after all that is about 11-12.

 

And no have not regeared yet. With the lift/ tire combo before mods i was getting that better milage, and after not so satisfied

 

How many miles have you driven since the swap out?

 

An easy 1000 or so

 

Have you replaced your speedo gear so that it compensates for your larger tires?

 

Gear no just sensor.i was fine with it 5mph off didnt bother me but now that it reads nothing sucks

 

If you don't replace the speedo gear then you don't know how fast or slow youre going or how many miles you are running.

 

That was kind of my point. It's difficult to calculate mileage without an accurate speedo/odo.

Regardless, there is no reason for your mileage to have deteriorated but it's difficult to offer a solution. I don't have a reason for it. Maybe someone else does?