Here is the scenario. I am a proud owner of a camper which is near maximum tow capacity for my truck. I weighed it full and ready to camp, and I had about 900 lbs left I could add if I had to, including family, and extras.

I pulled the camper 100 miles to the lake, and everything worked like a dream, except when I disconnected the truck, and drove around the park, I had a loud vibration from under the truck that sounded like a heat shield vibrating. I cringed and thought, maybe it was my transmission, but the transmission seemed to shift fine, and never got over 195 degrees for the trip. ( I monitor it along with engine temps and misfires with the Torque App)
Pulling the camper home, I made the mistake of setting the cruise at 60 MPH. (Lesson Learned) I was climbing a large incline when the engine downshifted to what I assume was 1st gear, and the engine revved up to around 5 grand or more. Before I could get my foot to the brake to cancel the cruise, I heard a noise that sounded like twisting iron. My check engine light started blinking and I started reading a misfire on cylinders 5 and 6. I watched the count on them, and for the next several miles I saw no more errors. I reset the code to see if it would reregister later. It did not. There were no misfires the rest of the way home, but there was a tick noise from a single cylinder that sounded like it was tapping on sheet metal. I later determined that it wasn't a mechanical tap, but more of an exhaust noise. When I came home I disconnected the trailer, and the truck drove fine, except for the tick noise.
I drove across town to lunch and the truck threw a P0430 error, (bank 2 cat) I had previously had that error when a packrat chewed through my 02 sensor wires, but I had repaired the wires. I went to the parts store and purchased a new 02 sensor to replace that one, but the error returned. ( I wanted to eliminate that as a possibility, but maybe wasted my money)
I found the O2 sensor reading feature of Torque, and saw that each of my downstream sensors read way different. After some research on the internet I found how to read them. The bank 2 sensor is mirroring my upstream one, and so I suspicion a bad cat converter. I ordered a new cat for it and will put it in this weekend.
Now to my question. Once the new cat is in, and I monitor the engine for misfires, what else should I do to prevent this cat from being a problem again?
I guess what I am asking more in detail is, Since cylinders 5, 6, and 7 had misfire codes 5 (29 misfires), 6 (85 misfires), and 7(96 misfires) during that short period of time, how do I determine its not an injector issue, or a coil issue.(sprark plugs have 5,000 miles or so) (the misfire only occurred during that short period of time before I got my foot on the brake to kill the cruise) No misfires since.
Should I suspect the cam phasers, or the VCT solenoids as part of the problem since they are all on one bank? Would a plugged cat cause three cylinders to misfire at high RPM, or did the misfires plug the cat?


I appreciate you taking the time to read and thank you in advance for any advice you can offer.

 

I just replacec all 4. One was bad. ll mine. No idea why I e went south. Seems to be fine now.

 

I received the driver side cat on Thursday and replaced it Saturday morning. I cleared out the errors, and drove it. all seemed to register fine. It will take several more trips before the computer will register all devices again, so It's a wait and see. The inside of the bad cat was a bunch of rounded off *****. Once I started the truck, the O2 voltages showed good, so that made me feel better. I still have a ticking noise that I am convinced is a single cylinder exhaust leak that I need to find and fix, but I feel like I am getting closer I just can't determine which side its coming from yet.

 

Suspect phasers ?? Maybe, but I don't think so at this moment. The PCM is closer to the problem (and watches very close), trust its codes. If cam timing is off more than 5 degrees, for more than 5 seconds - it will set an over advanced or over retarded code as appropriate. On startup, if phaser is not at base timing during startup (when engine is initiating firing order - etc) the PCM has trouble locating the 5th finger on the phaser and will set a P034x code as appropriate.

And the misfires probably were the SOURCE instead of the CATS. Here is how I cured my misfire problem. My '04 has 245k miles and I routinely run 50 - 70 - even eighty drive cycles without registering a single misfire.

Since you are a Torque Pro user, you might find the 'live misfire monitor screen' like this Torque dashboard I posted on the Torque Pro site.

 

Awesome! I was hoping you would chime in, I have read many of your posts, and have a huge respect for your opinion. Fortunately, I read your post from how you cured your misfire problem and followed it to the letter while swapping out my spark plugs. (They all came out clean and without problems) and I did clean out the holes real good, to where they screwed in to seat by finger.
I love your Torque setup you posted, I will set mine up like that.
Previous to this Catalytic converter error, I watched my misfires religiously, and would only see one misfire in the system on a very, very rare occasion. I believe I had only had one or two since changing to the new plugs around 5,000 miles ago. That was until I was pulling the camper a couple of weeks ago. Then, in that very short period of time, I had quite a few. I could feel the jerky misfires that felt like a tiny machine gun pattern for just a very short time. I have driven the truck quite a few miles since Saturday and haven't had a single misfire. I will keep this thread updated. I did determine over lunch today that my ticking noise is a bad manifold gasket, or cracked manifold on the passenger side, so I am beginning my search for a proper manifold to replace it with.
Thanks again for your wealth of information.

 

The kind words are much appreciated. Try to keep those 'jerky' misfires down any way we can. I believe they play a big part in trashing guides.

There is a lot to be learned about the misfire thing on these trucks. The PCM treats them in about three different classes ---. The ones during the first 200 revolutions on startup sorta don't count for much - (They don't stomp the 'Last Misfire freeze frame fields'. but "I THINK" they become part of the weighted moving average of misfires during the last 10 drive cycles on Mode $06. Then there are those counted during each 1000 revolutions (counter reset every 1000 revs) for determining misfire rates exceeding factory Spec. Apparently that accumulator for 1000 rev count is what leads to setting a DTC. For sure, that is the counter that causes the Flashing CEL when that count for a given 1000 Revs exceeds the catalyst damaging rate.

If you implement the Torque Pro dashboard I linked in the prior post, you can kinda develop a sense of these. I can 'create' a [ <200 rev misfire] by turning the key on for about a minute before switching to 'start'. I'll see a misfire on individaul cylinder misfire count (usually on cyl 5) and MFTot of 1 or 2, but the number of drive cycles without misfire (MFF_0_CNT) doesn't reset. They also don't show up in the freeze frame data in lower part of the dashboard. --- I think that actually tells me my #5 injector must 'weep' a drop or two that makes that cylinder too rich on startup. but that's another post subject.

I love the fact the PCM keeps track of this stuff, even when we aren't on this Torque screen. I pop it up every once in a while and get that warm fuzzy feeling when I see MFF_0_CNT up around 70 or 80. Whoaaahh



My Drive cycle count (DRIVECT) without clearing DTCs was up around 3200 (over 30,000 miles) but I left my damn dash cam ON and was in hospital three days ---- F'n battery went dead!

Cheers my friend.

 

Thank you so much!!! I find your knowledge very valuable!