I have a 98 Cherokee with a 4.0 and it is loosing mpg it use to do good. But I'm using double the gas now than what it took 3 months ago. I have a miss at idle sometimes not always. But when it does the check light comes on but the next time I start it it goes out. Need help on what could cause this. Thanks

 

Pull some codes. See your local Autozone or Advance Auto. They will pull the codes for you. Report back.

Some typical suspects for severe loss of mileage:

1. Vacuum leak.
2. Bad 02 sensor.
3. Bad 02 heater.

Codes will tell you a lot.


Check your tailpipe, too. Lots of black soot? Do you leave a black cloud behind you when you accelerate hard?



By the way, it's "losing", not "loosing".

 

Thanks I'll check the vacuum lines,and the o2. Oh and thanks for pointing out I missed spelled a word. That's why I posted to have my spelling checked. Lol

 

You post to learn, don't you?

Get the codes, or you'll be shooting in the dark.

 

I'll try to get the codes when the light comes on again. Thanks