Does your 5.4 destroy catalytic converters?
02-28-2017, 09:02 AM
#11
145k on factory cats here.
02-28-2017, 09:09 AM
#12
Moderator
130k on factory cats.
02-28-2017, 10:17 AM
#14
Lots of high mileage kitties in here 
02-28-2017, 11:23 AM
#15
Monks
Thread Starter
The truck has been maintained meticulously. There was no misfire before the cat let go. When it broke apart, I got a P0303 (cyl 3 misfire). I also replaced the #3 spark plug and COP to be sure I wouldn't have anymore issues on that side. I plan on doing another plug change this weekend on all other cylinders to make sure there is nothing to surprise me. The only thing I can think of is a factory defective cat, or the previous owner had some issues before the 61k that I bought the truck at. Other than a p0420 and p0303 (at the time of the failure), no other CEL's have ever been thrown.
02-28-2017, 01:22 PM
#16
Senior Member
You do not have to have a code pop up to have a miss. In fact, the system will allow for a pretty high number of misses before it triggers a code.
Unfortunately many people do not even realize they have a miss condition until it is too late.
How did you know the cat went bad? Rattle?
Did the code pop up at the same time as the cat going bad or just before?
Unfortunately many people do not even realize they have a miss condition until it is too late.
How did you know the cat went bad? Rattle?
Did the code pop up at the same time as the cat going bad or just before?
02-28-2017, 01:39 PM
#17
Monks
Thread Starter
anything over 10% throttle, the truck would break up, pop, misfire. No power at all. What happened is the cat broke apart inside and when I gave it throttle, the crap shifted to the back of the cat, clogging that bank of exhaust gas. The P0303 came up when it started running like ***. Replaced the cat and the #3 plug and COP, and drove 1200 miles to and back from Galveston without another issue.
03-01-2017, 01:20 AM
#20
I have replaced my cats 3 times already. Twice before 80,000 because I had put on my CAI without tunning it (Did not know any better!). Took it off after the second time.
Third time I was around 120k. Got the cats replaced with all plugs and a few COPs.
Right after Christmas 2016, my CEL started flashing but by the time I would get to the auto parts store to get it checked out, it would turn off. In the beginning of February the CEL stayed on and got the dreaded P0420 code. Along with the code, I started getting some misfires but I can't pinpoint which one it is. My engine misfires when I gently accelerate from 40-60mph which is why I think my cat started going out.
Third time I was around 120k. Got the cats replaced with all plugs and a few COPs.
Right after Christmas 2016, my CEL started flashing but by the time I would get to the auto parts store to get it checked out, it would turn off. In the beginning of February the CEL stayed on and got the dreaded P0420 code. Along with the code, I started getting some misfires but I can't pinpoint which one it is. My engine misfires when I gently accelerate from 40-60mph which is why I think my cat started going out.