Pat Healy

Hey everyone im new to the jeep comminity. I have searched everywhere and can't seem to get a answer to my problem. I have a 00 Cherokee 4.0 that just started running misfires on cylinder 1,2 and 3! I also have a code for a bad O2 sensor. Ive checked all the plugs and im not sure what to change next. I turn the key once and it wont start but turn it a second time and it will. I dont know what to change next Sorry if this is a dumb questions im new to the car world lol
Thanks for any help at all!

fb97xj1

Whats the code? California emissions have 4 sensors, others have only 2. Whats the fuel pressure? What did the plugs look like? Do you have a scanner that can read live data? Needing to turn the key twice before it starts is usually a failing fuel pump. This can have an impact on the O2 sensors. Did the fuel pump prime on both turns? When it wouldnt start, did it still crank? Many questions, but the more info, the better, as a misfire can be caused by many things.

Pat Healy

Sometimes when it warm it starts first turn no problem. Just changed the fuel pump with a brand new one. The codes it's pulling up is for a misfire on cylinder 1,2,3 and the second bank 02 sensor. I dont know if i should change the 02 sensor or wires. All the plugs were changed and im not sure what to do. Thanks for the advice all the help i can get is great

fb97xj1

It wasnt an Airtex pump, was it?

Pat Healy

the shop did it for me so im not sure. it struggled to start when i first got it and there was no check engine or anything. the first time the light came on it was for an evap leak and they fixed it by putting in the new pump