specialkeay

I have a 99 grandcherokee 4.0. The check engine light came on so I ran an OBD2 diagnostic and said cylinder 3 misfire. Does it have a coil pack that I need to change.

bones99xj

Depends on when it was made. The earlter 99's didnt have coil packs they had wires. Later 99's and up had coil packs. If you have coil packs then you wont have to change any things expect the plugs. If dont have a coil pack then you'll have to replace the cap rotor wires and plugs.. good luck.

specialkeay

No cap and rotor. The coil pack is a first for me all my other jeeps have been older, So just replace the pluggs and I should be good to go?

bones99xj

Yup. Id throw in an air filter and a pcv vavle as well. But plugs is all you need.

jnicewan

Try plugs first, it could still be a coil assy or injector or something in the base engine. When you are replacing the spark plugs, look at the coil assy and the rubber boots and make sure one of the boots is not split or another concern particularly on cylinder 3. Inspect the spark plugs for a misfire concern again paying attention to number 3.