Catalytic converter super hot

Jim W

New Member
Joined
Apr 7, 2016
Messages
7
Location
Minnesota
Need some help
I have just replaced my 4.0 with a stroked 4.6 I started it up for the initial run in (20 min @ 2000 rpm to seat the rings) and I noticed that the front exhaust pipe (the one with the little catalytic converter on it) got cherry-red hot, but the rear one did not... what's up with that
 
A cat normally gets very hot when in use, but not glowing hot.

Something is causing raw unburned fuel to be sent down the exhaust pipe where the cat "burns" this fuel. The cat is designed to burn the tiny amount of unburned fuel that comes from a normal engine. Now, if you pour excessive hydrocarbons (fuel) in the exhaust, the cat will burn that too and since it's burning too much fuel it glows red hot. This won't last very long, this is very damaging to the cat. The catalyst can get hot enough to melt. And that won't take long! And when it melts, then you will have a blob of molten metal blocking the exhaust pipe (now it's clogged!) and the engine will stop operating. At that point, the only fix is replacement of the catalytic converter.

However, if you find and fix the problem now you can avoid that expense. You have to find why raw fuel is going through the engine. The most common reason would be a bad spark plug or bad spark plug wire. If the spark doesn't work, there is no "combustion" in that cylinder and the raw unburned fuel goes out the exhaust pipe.

My guess is that since this is a result of the newly installed 4.6 stroker, you may very well have some sort of fueling issue.

Are you throwing any check engine lights at all? Does the vehicle smell like it's running rich?
 
thanks for the informative response and so quickly,

Yes the codes that are being thrown out are 123, 352, 353, and 132. This makes sense the coils are on the cylinders that exhaust into the front pipe and the O2 sensor is on that front pipe. Is it possible that I don't have the coil bar down far enough or could it be bad?
 
Could be a bad 02 sensor sending continuous a false lean condition report fooling the ECM into running the air/fuel mixture full-rich to try to get the mixture correct.
 
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My thought is potentially a bad coil, or O2 sensor(s). I would address each one of those codes it's throwing individually.
 
Thanks to all that gave input .... The resolution of the problem I replaced the coil because primarily I got error codes on the coil (352, 352) but it turns out that when I installed the engine I forgot to plug in a couple of o2 sensors (Check the details) and when I put the new coil bar the boot for the spark plug missed the mark ( wow details again) but after checking these things and as it seemed almost everything else under the hood it runs great.

Again thanks for everyone's help

Novice engine rebuilder
 
Curious. How did you determine the timing was off? And how was it corrected?
 
Thanks for the update @Jim W! That makes perfect sense that the timing was off.

I'm glad you got it sorted out!