1992 jeep Cherokee fuel consumption

[garrett6410]

Hear lately I've noticed my jeep has been getting extremely bad gas mileage such as about 8-11 mpg. Used to before I went up to 31s I was on 30s before it was getting about 17 18. It's got a new 02 NTK new sparks and newish spark plug wires replaced within 2 years any tips to help my gas mileage would be well appreciated and it also seems to have a miss I'm not sure on what cylinder or if it does at all it just seems to idle a little funny 

[87MJTIM]

O2 sensor stuck in open loop?

[TurboedMJ]

3 hours ago, 87MJTIM said:

O2 sensor stuck in open loop?

How do you test this... I am having the same issues. 

[87MJTIM]

I can find Renix O2 testing.  I think HO sensors work on diff scales.

 

https://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

 

Scroll down to the O2 sensor.

[garrett6410]

2 hours ago, 87MJTIM said:

I can find Renix O2 testing.  I think HO sensors work on diff scales.

 

https://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

 

Scroll down to the O2 sensor.

I'll have to look into that any other things you can think of

[cruiser54]

The hose from the intake manifold to MAP sensor?

 

Any vacuum leak there will tell the fuel injection system to add more fuel. 

[Eagle]

Did you change the speedometer gear when you switched to larger tires?

 

If not, the odometer is off and you have driven significantly father than what the dial shows. Which means your fuel mileage isn't as bad as you think.