Running bad

[Dave W.]

Started up the 99 Ex 4.0 this morning, It was running rich and stmbling for about 5 minutes then it seemed fine. Took it out on the highway to blow the gunk out of it for about 10 miles @ 55mph, came back into town driving around and check engine light came on and stayed on. Came home disconnected the battery and her cool down, connected battery back up after a couple hours started it up same problem stumbling and burnig rich again for about 5 min. out on the highway I go come back into town, check engine light came on again. anybody know what is wrong?

 

[Jason_25]

Sounds like an oxygen sensor to me. You have four of them by the way.

 

[mrboyle]

I agree with Jason, you have a bad oxygen sensor.

 

[Explorerdude]

Did you try cleaning your MAF? If not it may be a quick simple fix. I don't know much about the 99 4.0 but I know in my 94 it has helped me out more than a few times. There is a thread on this site under FAQs. Good luck!

Happy Wheelin',

Joe

 

[Dave W.]

Thanks guys about the o2 sensors, and I did clean mass airflow sensor 2 weeks ago.

 

[Dave W.]

Yes it is an oxygen sensor, had it in the shop and they checked it out. They won't have the part till Thurs.

 

[Dave W.]

All fixed, runs great again! Thanks everybody!