Piss Poor gas mileage

[95xjsport]

I am getting about 12 mpg, is this normal for a '95 cherokee? I have the 4.0 I6.
all I have done to it really is:
- custom Cold air intake with ram air
- 19lb/hr ford racing fuel injectors
- Intake Airflow Sensor replaced with a resistor to trick the computer
into thinking that it is "breathing" cold air
- High flow cat
- Flowmaster performance muffler
- 180 degree thermostat

I am getting some nice Horse Power but the whole 12 mpg really sucks. well, it does has just over 152000 miles and the aerodynamics of a shoe box.

[IdahoJeeper]

Hi there,
I'm no rocket scientist, but I think you might have a couple problems...

First the resistor. I thought about doing the same thing, but I considered the possibility that the sensor is there to moderate the fuel/air mix. Cold air is going to expand more in the cylinder when heated and therefore more oxygen means we can dump more fuel down the hole. (hence the more ponies) Because it thinks you have cold air, the computer is allowing more gas into the cylinder. In fact the seller of one of these resistor mods states you may see a 1-2 mpg drop. The second part of this is we like to feel the power, and so it's possible your foot is into the pedal more. My 96 gets 15 to 20, dirt vs hiway, and aside from improved intake air, it's stock. I would say it's a trade off. Ponies or mileage.

I might also ask, although I'm sure you already have... Did you make sure your cap/rotor/plugs/wires/fuel filter are all in good shape? All the mods in the world don't mean crap if the rest of the system is weak. Just the basics.

If you want to cram more air in, take a look at one of the bored throttle bodies and a bored spacer. I've also seena cool way to take the intake manifold from a 2000+ model and mod it onto a pre2000, the newer intakes have way better air flow.

Good luck!

[gtmud]

I agree with Idaho, I think your main problem is that resistor mode. Your engine is now running like it was just started on a cold january day, this constent will drop your milage considerably. Like Idaho said, if you want power you will sacrifice milage especially when your talking increase fuel demand.