Popping in the exhaust P0430 and P0300
09-23-2020, 06:28 AM
#1
JK Newbie
Thread Starter
Popping in the exhaust P0430 and P0300
Hope this is the right place for this.
I first got the code P0430 bank two cat bow threshold. This 08 jkus is used but new to me as of July this year. 139k miles.
Having trouble shot cat codes before and won on different vehicles I go for checking combustion items first... especially since the code was only left side. No codes for bank one.
Replaced spark plugs. Used my scanner and removed the code. It came back two days later.
Replaced plug wires...now I have both code P0430 and P0300(random misfire) it runs rough as hell, I hear popping in the exhaust.
How does it get worse? I've searched all over.. firing order is correct. No air leak..no exhaust leaks.
I'm certain the cat code is being caused by inefficient biurning and excess fuel is getting to the cat.
How though, after new plugs and wires does it get worse and misfire?
Little history: I had a dynomax muffler that was loud and replaced it with factory. I have a K&N cold air. It ran fine after I replaced the muffler. No codes. It seemed to run fine even with the cat code.
Update: after posting, I decided to back track to the last change as a point of failure. The spark plugs wires. I got a set of duralast OEM quality from autozone and replaced the carquest brand I put in from Advance. Instant reversal in the jeep's behavior. No exhaust popping or rough running. The popping was probably unburned fuel igniting in the cat.
BTW, for CAT codes find the source of the problem...quick fixes and masks will just make the code cone back and then you will have to replace the cat because the source of the problem destroyed the cat.
So what I learned here is that wranglers like certain level of quality parts. Unlike most of the cars I've ever worked on. Unless that is the part is just complete junk.
I cancelled the codes and I'll see if either come back.
I first got the code P0430 bank two cat bow threshold. This 08 jkus is used but new to me as of July this year. 139k miles.
Having trouble shot cat codes before and won on different vehicles I go for checking combustion items first... especially since the code was only left side. No codes for bank one.
Replaced spark plugs. Used my scanner and removed the code. It came back two days later.
Replaced plug wires...now I have both code P0430 and P0300(random misfire) it runs rough as hell, I hear popping in the exhaust.
How does it get worse? I've searched all over.. firing order is correct. No air leak..no exhaust leaks.
I'm certain the cat code is being caused by inefficient biurning and excess fuel is getting to the cat.
How though, after new plugs and wires does it get worse and misfire?
Little history: I had a dynomax muffler that was loud and replaced it with factory. I have a K&N cold air. It ran fine after I replaced the muffler. No codes. It seemed to run fine even with the cat code.
Update: after posting, I decided to back track to the last change as a point of failure. The spark plugs wires. I got a set of duralast OEM quality from autozone and replaced the carquest brand I put in from Advance. Instant reversal in the jeep's behavior. No exhaust popping or rough running. The popping was probably unburned fuel igniting in the cat.
BTW, for CAT codes find the source of the problem...quick fixes and masks will just make the code cone back and then you will have to replace the cat because the source of the problem destroyed the cat.
So what I learned here is that wranglers like certain level of quality parts. Unlike most of the cars I've ever worked on. Unless that is the part is just complete junk.
I cancelled the codes and I'll see if either come back.
Last edited by Damien Ristaino; 09-23-2020 at 07:35 AM. Reason: Update
