I had a similar problem, my 04 6.0 R4LE(?) wouldn't go above 70mph in OD, but would go 80 in third. I exhausted ( ) all other possibilities then cut the pipe in front of the third, unmonitored cat. Which is why no CEL. It would easily go 80 in OD. BTW, I got $175 for my old cat.
When my main catalytic converter suddenly clogged nearly completely it dropped my highway speed to 5 mph max, it would barely rev in Neutral.
I just went through this and the symptoms were as described by others..Zero power and any sort of incline would almost stop the jeep
I took a rubber mallet and smacked the converter and could hear crap falling and bouncing around
I may have accidentally cut an inspection hole in the converter body, removed the honeycomb that had fallen to the bottom and retested.
Is there any method to assure that my cat is clogged when there is no cel?
That works too, I recommended the vacuum gauge as it is a much more common tool than a back pressure gauge. I forgot with Amazon inexpensive tools are at your door in a couple days.
When my main catalytic converter suddenly clogged nearly completely it dropped my highway speed to 5 mph max, it would barely rev in Neutral.
Hey Jerry, is it possible for these issues to come and go? I’m am almost sure it’s the cat I’m having issues with. I was told about 2 years ago that one of them wasn’t as efficient.
The issues I’ve been having match the cat, but I’m still a bit doubtful mainly because I am confused on how it all works.
I’ll start the engine and if I get rough idle, I know if I keep driving it, I will have these loss of power issues. But if I turn it off, and back on, the rough idling disappears and I do not get a loss of power.
I did have check engine light p0432 but it has gone away. It has turned on in the past when I hit a bump. This was maybe a year ago. I guess I hit another bump and it came back on. It’s gone now. I’m bamboozled. It’s my daily, I drive it all week, and I want to say this only happens every now and then. How does restarting the engine affect this? I had this same issue 2 years ago. I had someone do a Tune up and it went away. Turning it on/off …. it is almost as if it fixes it when I do that, but of course it would only last while I drive it. It’s not consistent however.