Hello everyone, I recently took my '98 XJ through some water and it got stuck and was submerged up to the seats for about 1-2 hours. I got pull'd out and it started running real bad and was getting check engine light.

I at first got codes:
P0300- Multiply cylinder missfire
P0301- Missfire on cyl#1
P0306- Missfire on cyl#6

after I got those codes I thought maybe I got some water into the intake and might have foul'd the plugs.

I bought a new air filter, distributor cap, rotor, wires, and plugs and install'd them. When taking out the old plugs, I noticed cylinder's #1 and #6's plugs were both broken.

I replaced all that stuff and it runs a lot better but when I first start it up it's running really rough and is noticably missfiring. It drove all day kinda rough w/ no light... the light came on and got code P0306 again.... changed that plug again but no change except the check engine light went off for a while.

The Jeep is still running quite bad at low speeds is having a slight hesitiation and when first started it runs real rough. after I get up to speed it seems fine, and when I slow down to a stop it usually seems fine then.

what do you think is causing this problem? anything else that may have gotton wet may be causing the problem? any help would be greatly appreciated. Thanks.

could it be a burnt exhaust valve? is this common w/ water in the cylinders?

Do a search here and in the Grand Cherokee forum for multiple misfire. I'd suspect your crankshaft position sensor, possibly.

Also, after being drowned that deep, you will want to change all of your fluids, since they're likely all contaminated. There have been several threads about auto trannies dying shortly after being submerged so I wouldn't drive the vehicle until that is done.