Re: 1999 cherokee o2 sensor mess
I don't know if your 1999 4.0 ignition system is the same as for the 2004. On the 2004 there are 3 coils in the rail. Each coil fires two cylinders at the same time, from which one spark is waisted. Since yours only says ignition coil #3 circuit, i wonder if the 1999 has an other type of ignition coil. Maybe an other member with experience on this can chime in.