2002 Protege w/2.0L problems

[jenga]

Greetings,

I need some help. I have a 2002 Protege with 137k on the 2.0l engine.

I've had issues with the car stalling and then not starting in the past. However, the issue was intermittent.

2 weeks ago I was driving along in very cold weather and noticed my car was loosing power very quickly. I had it to the floor just to get off the freeway. Then the exhaust became very loud and sounded like it was coming from under the hood. The car stalled out on the off ramp and hasn't started since.

I have 3 OBD codes stored in the computer. They are p0421, p0300, and p0480.

I had a friend stop by yesterday and we cleaned the MAF and changed the coils. But when we tried to start the car, black smoke poured out of the pre-cat on the manifold. This tells me that the cat is clogged and a hole was burned through the wall of the precat.

Now here's the scary part. I'm concerned that the engine melted down due to the excessive heat created by the clogged exhaust. Has anyone heard of this problem? Any idea what to check next?

 

[civickilla03]

tow that bad boy home and take it apart, you'll know for sure what the problem is then, other than that i dont know what to tell ya, im no pro.

 

[jenga]

Yeah, I'm working on towing it to a friends garage so we can work on it. He suggests that we remove the exhaust manifold and start with a compression test. He believes that I melted something in the engine and that's why I'm getting a misfire code.

 

[P-Funk!]

I doubt it.

A bad misfire undiagnosed could clog the Cats.

The 'blow out' jet of hot gas would not damage the engine. Inspect carefully where the jet of hot gas blew - what was it hitting? Did it turn blue-ish?

 

[protoga45]

Its hard to spot the exact spot. If it were blue-ish, what would that tell me? At this point i have disconnected the 1st cat from the exhaust manifold to eliminate any potential clogs to prevent additional exhaust blow back. I am going to try starting it that way but my battery has started to die.

while i was checking compression the tube that connects to the threaded part of the tester loosened and now I cant unthread it. Anyone have an idea how to get it out?

 

[jenga]

So we removed the spark plugs and rotated the engine by hand and felt no unusually difficult turning points in a full rotation.

The timing is dead on. (The I and the E are facing eachother)

The precat has a hole in it the size of a softball on the front side. The honeycomb material was molten.

Everything seems ok with the internals and exhaust side. It it possible that the obstruction in the cat caused damage to something on the intake side? Is it possible that the exhaust was traveling back through the intake valve on the intake stroke?

 

[njaremka]

i believe the 421 code comes from the EGR valve. if the valve is original to the engine, i would replace it - it will be way over due by now.

 

[jenga]

The EGR has been replaced. Could a clogged EGR pipe from the exhaust manifold to the EGR valve prevent and engine from starting?