I have a question on my 2000 xj 4.0l. It has 263,000 miles on it and when it first starts when cold it will misfire for less than 15 seconds then is normal but after I make any length of a drive when I put it in neutral and let it sit for maybe 30 seconds to a minute, it will start misfiring and blow a ton of blue tinted smoke out of the exhaust but as soon as I put it back in drive and take off it will stop and not blow a single cloud of white or blue smoke at all and will not misfire at all anymore. Thought it could possibly be head gasket or maybe crack in the block somewhere. Could anyone give any suggestions on what it could possibly be please.

Thank you, Paul.

 

When's the last time you replaced spark plugs?

Any engine codes?

 

If the head is original, and its a 2000 with that many miles, it's probably cracked. Could also be a combination of bad head gasket and leaking valve stem seals. Misfire is probably from the spark plugs like cruiser54 said, they are probably fowled up good.

 

I'm surprised your 2000 model engine lasted that long.

If you're going to keep the Jeep, plan on pulling the whole engine for a rebuild. Scrap your 0331 head and buy a new head from Clearwater.

If you don't want to do that, sell it now while it will still run a little. With disclosure.