I dont know. I live in oklahoma and there is not any hills and i get 10 mpg on the highway. So i dont know what you should be getting. Stock and aggressive i would think 16 or so.

 

Source = Fueleconomy.gov
1997 4.0l / Automatic Cherokee 4x4
13 MPG City
15 MPG Average
18 MPG Highway

1987 4.0l / Automatic Cherokee 4x4
15 MPG City
17 MPG Average
20 MPG Highway

2000 4.0l / Automatic Cherokee 4x4
14 MPG City
16 MPG Average
19 MPG Highway

 

i like how the 87 is rated better than the 00

 

I thought that was funny to. I am plutting a 99+ intake on mine soon. I will report back if that improved fuel economy.

I'm not really understanding the fuel injectors thing...I get why 4 hole is better then 1...but what application would I need to find to upgrade my 97? I am confused.

 

4.0cherokee
What rear end gears are in yours?

 

3.55 stock 8. 25

 

So on some older vehicles I know that the when the car was cold it gave the motor more fuel so it would warm up and once it warmed up it would let the computer take control of it and back the fuel off. Does the jeep have this? Becuase if it did and my computer never got to take back control when it warmed up then that would be a reason why it would be sitting there dumping fuel all the time.

 

Still applies to newer engines. The rich fuel mix for warm up is controlled by the ECM and gets the input via the coolant temp sensor. There are two temp sensor's, one for the ECM and one for the gauge. If the temp sensor was not functioning correctly you should be experiencing a harsh idle once the engine is up to operating temp.

 

no temp works just like it should. It runs ruff at all temps. I am hoping that it is just a messed up injector. If not I dont know what else i am going to do.

 

Do you have a Haynes or Chilton manual for the Jeep? Ifnot I recommend picking up a chilton manual. I'd try testing all your sensors to see if you can't find a bad one, because most likely your Jeep is getting stuck in open loop mode and thats why its just dumping fuel.

Since your temp sensor seems to be working I'd try the IAT(Intake Air Temperature sensor) or your MAP(Manifold Absolute Pressure sensors). Most likely your injectors and fuel system are fine and instead your problem is the ECM is getting bad readings from a messed up sensor and as a result is dumping excess fuel into the engine...which can also kill your cat

 

Yea I have thought about that as well. The only thing is that it is random. That is why I am checking the Injectors first becuase I am hoping one is just messed up to the point it cant really mist it into the cylinder and it is just dumping it in causing it to not burn all the fuel that stroke. I am going to do the sensors next after I get my injectors in, and see if that fixes it. I am crossing my fingers that it does.

 

Like I said before thats what happened to my truck when I put in that dam super chip.

 

no performance adders.
Winston said it was slower than his xj with 33.

 

totally missed that part

 

I had a full size truck with a super chip,dumped lots of extra fuel to up performance,saturated my cat wrecked my o2 sensor screwed up my computer.