Glowing-red exhaust on a 4th gen Ford Mustang

This evening as I was getting back home from work around 9:30pm on the highway (36F temp and 65mph cruising), I notice in front about 70-100 feet and on the lane to the left of me, a white, 4th generation (1994-2004) Ford Mustang.

The undercarriage about midway the length of the car had a rather odd orange-ish hue. At first I thought there were some bulbs hanging under there or those tacky undercarriage lights that some fans of the 2Fast2Furious movies, burden their cars with.

However, at least 3 times I noticed sparks being left behind the car which leads me to believe that the middle part of his exhaust system was the thing that was glowing orange and not some bulbs.

Could that have been his catalytic converter or converters?

What would cause it/them to glow red-hot?

The converters work by being hot, red hot. That is why they come with heat shields. They are hot enough to start a grass fire.

It seems that either the manufacturers have improved their design and/or owners have become more careful, but fires seem to be almost nonexistent these days.

Common result of engine running rich. Almost had nasty fire when temp sensor failed and computer thought engine was cold. Dumping fuel into engine and converter was red hot. The carpet on pass side was smoldering…

If that exhaust pipe was plugged up, the pipe ahead of the restriction will glow red. In fact if you could see into the engine compartment the header(s) would be a nice cherry red up to the head.

As you surmised the catalytic converter could be melted or otherwise restricted causing the exhaust restriction. It also could be a crimped tail pipe.

Cats DO NOT GLOW UNDER NORMAL CONDITIONS. They get hot…very hot but they SHOULD NOT GLOW RED. If they do then the engine timing can be too far advanced…OR they are running the engine…too LEAN… This vehicle had a serious issue that the owner should have known about. God forbit he parks over some leaves after he got home…POOF it will go up in flames.

Advanced timing or LEAN/NOT RICH fuel conditions will make the Cats/Headers glow.

What? It’s a CATALYST. When it converts fuel, it gives off heat. The more fuel the hotter it gets. Most cats are too far downstream to be affected by LEAN conditions conducting heat down the exhaust pipes.