Hey guys thanks for the help in advanced.
so this past weekend I got stuck in a pretty deep puddle. lol.
flooded the interior.. blah blah blah.



well I got the jeep home and it was running a bit weird so I took the wiring, cap and rotor off. there was some moister in there and I cleaned it out. I took all the carpet. clean it and put it back in. well it sat for a few days while it all dried.

i went to fire it up today and it was running super weird and sluggish also making a weird hissing sound. then the check engine light came on. went to autozone and they read it. came back as P0171. which is bad fuel/air mixture.
could be MAF sensor, 02 sensors, injectors.....

but I was checking the intake gaskets and stuff and came across this.





seems to be a crack in my header. if you notice the small line. and the black around it.
could this be the cause of the P0171?

thanks again for your help.

 

The hissing sound you mentioned...was that coming from this area?...Because hissing sound is usually more like a vacuum leak...

 

Whistling is vacuum leak* Hissing is exhaust.

Congratulations, you XJ has completed the 4.0L rite of passage by cracking its exhaust manifold. Yes it is the cause of that code because exhaust gas isn't making it to the O2 sensors.

Many many threads on replacement manifold and headers. Have fun shopping! APN seems to be popular. I was just a little noob when mine broke so I have a Dorman OE style replacement with bendy sections on 1 and 6 runners.

 

I'd swear my vacuums have always been hissing i.s.o. whistling...must be the continent..

 

Welpppp I replaced the upstream o2 sensor and it seems to have fixed it..? But it's a jeep so we will see haha