agrasso5567

First off here are the codes it's throwing ( 2001 jeep cherokee 4.0L 4wd)

P0303 cylinder 3 misfire
P0455 evap emission leak LARGE
P0300 random / multiple misfire
P0306 cylinder 6 misfire
P0456 evap emission leak SMALL

So i had the cylinder 3 misfire for a month or so now but I could never get it to stay off. I replaced the spark plugs, and the boots on the rail. It turned off for a week or so until it came right back on again.

It ran fine until I took it in some deep mud the other week. I had water over the wheels and got stuck in the mud for a few minutes but after i got home i checked the codes again because it started making a sort of hissing sound coming from the lower engine bay area.

The other 4 codes popped up then. I have a hunch it might be the fuel filter but I need more opinions.

The hissing sound gets louder as i give it gas and isn't too noticeable when in Park. Could the sound just be the cylinders misfiring or could it be some sort of exhaust or gas leak maybe?

I've taken it into deep water before and have never had any problems like this. It has much less torque and just lacks power overall right now. Any suggestions are appreciated.

KG8893

Parts of the evap system run the length of the frame rail alongside the fuel lines. I'd bet you snagged it on something in the mud. As for the misfires, It could be completely unrelated. Try checking/cleaning the grounds that are on the coil pack rail. I've heard they can cause bad misfiring issues. I highly doubt you are dealing with a fuel issue... If you wan't to change it, the fuel filter is located inside the gas tank; have fun.

agrasso5567

All the grounds on the wires are fine. I'm going to rule everything else out before I go near the fuel filter. The hissing sound ended up being an exhaust leak at the manifold front pipe connection. Havent had much time to look at anything else the past week