OBDII Troubleshoot Misfire 4.6 MPI

[Laxpro1376]

This is my first post on genesis owners and hope this is the right place for this.

On the way into work today my 2009 genesis 4.6 with 150,000 started a misfire after riding through a puddle deeper than expected. I do not think any water went in the intake but may have reached the exhaust. This also could be unrelated but was the only thing out of norm on my commute this morning. Shortly after driving through the water the flashing check engine light came on and the car had a noticeable misfire but seemed to sort itself out and drive normal for the last 2-3 minutes of the drive (I work close to home). I checked to see what codes would show up on my OBDII and it showed P0158, P0308, and P0017 all "pending" with no more check engine light. Then at the end of the day the car started up quick as normal and I figured it was okay with no check engine light and no misfires in the last few minutes of the drive. I got out on the highway and the misfire started again but did not go away and I limped it the rest of the 10 or so minutes home. The blinking check engine light was on intermittently along the way and ended up staying on. After getting home it showed the following codes P0300(freeze frame), P0420, P0308, P0301(pending), P0307(pending), P0014(pending), P0016(pending). I have started it a couple times since getting it home and it starts right up and then the misfire develops and I turn it off. There is no sound of timing chain slapping or anything obvious like oil or fluids leaking. After turning the engine off and getting out of the car there is a clicking sound coming from the top of the engine bay, can't really narrow it down but it sounds like it could be electric. Since I bought the car the only check lights have been for the PCV valve and the purge control valve, both replaced on my own with dealership parts. Hoping someone has experienced similar or has any wisdom to share. I will probably be taking it to the dealership in the next few days anyway, but for now its parked.

A few possibilities I'm considering:
Wondering if water could have disturbed the post cat O2 sensor/cat sending a bad signal back and messing with timing...
Maybe water disturbed electronics like the ECM...
Stretched/jumped timing chain...

Hopefully someone more knowledgeable can shed some light.
Thanks in advance!

 

[Ketchupmothafcka]

I would definitely look into the O2 sensor first. Its in the right spot the get messed up by water.

 

[16UltV6Guy]

Wouldn't think it's a timing chain issue.... that would be too coincidental. I think it's something to do with the puddle excursion. Something got messed up electrically. Research those codes.... see if they can provide any clues. Agree with the condiment mf'er..... the O2 sensor would be a good place to start. Also, that clicking sound.... try to figure out where it's coming from. Get an automotive stethoscope.... they work good for stuff like that. Harbor Freight has a cheap one.

 

[Laxpro1376]

Update: The engine starts and sounds perfect after a few days of "drying out" (a.k.a. trying to avoid expense while driving a different car). I started it up and a small amount of water came out of the exhaust. A misfire still develops after about 45 seconds, but starts on all 8. I have noticed a stronger smell of combustion gasses than normal and can actually slightly see steam/vapors coming from exhaust under drivers side of car (maybe clogged cat?). The electric clicking after shutting the engine off has stopped. Things seem to be looking up, I will clear codes and start it up again to see what codes it gives me this evening. Still thinking a fouled O2 sensor could be a problem, maybe damage to the cat from thermal shock? Hopefully this additional info is useful.

 

[Genesis4.6TS]

Laxpro1376, how did you resolve your issue? I have a similar mileage 4.6 and just got multiple misfire codes on one bank and a slightly stronger gas smell than normal too.