rstuart931

2001 Cherokee limited started making what sounded like a metal on metal knocking noise, the noise went away for a second and then it started misfiring really bad and the check engine light started flashing. I pulled over and had it towed to my house. The codes it gave were P0300 - random multiple misfires, P0305 - cylinder 5 misfire, and P0306 - cylinder 6 misfire. I pulled the valve cover and inspected the valve springs, rocker arms and push rods - they all looked fine. I started it for a couple seconds and it belched out a huge cloud of white smoke from the exhaust and was misfiring really bad. Has anyone gone through this? What should I check next?

Edit - I should have noted the mileage, over 230,000 miles

exasemech

Check the compression. The metal on metal noise and the white smoke doesn't sound good.

That Jeep Guy XJMJ

Dead engine. . . Oil level? Pull the spark plugs on cylinders 5/6 and inspect for debris?

rstuart931

All fluid levels are good, just changed oil last week. I'm looking for how to check the ignition coils with a multimeter and will check the spark plugs when I do that. A friend mentioned checking the timing belt as that could explain the "clicking/knocking sound" if the belt was smacking against the housing and also explain the misfires.

exasemech

Not to sound like Dr. Doom here but.....

A couple things.
The belt,the only belt, is not a timing belt and any issues with it would not cause misfires.
While it could be that a fuzzy bunny dropped something into the engine that caused a metal to metal knock and white (oil) smoke it's likely when you pull the plugs one or more of them are going to have oil and piston on them.

But who knows, diagnosing stuff by internet is tough...it could be just the fuzzy bunny 🐇.
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