2005 Sierra 4.3 Catalytic Converters are red after installation

[Stephen Smith]

I recently installed new cats on my truck and I noticed that they are somewhat glowing red. Is this a problem?

The old ones were both bad, one was totally clogged with rock hard catalyst and the other had a lot of broken up pieces inside.

Also, my number 1 spark plug wire keeps popping off. I'm guessing I may need a new wire.

I have the Live Data saved to my computer if anyone is willing to take a look through it and look for any potential problems.

[Doug_Scott]

Not unusual for exhaust near the manifold to glow red when left idling for long periods of time, especially if the idle speed is being held higher than normal.

 

I have found the most common reason for the wire to pop off when it gets hot is due to air being trapped inside the plug boot when it is pushed straight on without dielectric grease. Once the wire gets hot, the air expands and pops the wire off. It is even worse on damp days. Twist the wire CW-CCW as you press them on. Also try to squeeze the boot off centre to try to release any air caught. Make sure the wires are properly inserted into the stock retainers along their path. Note that excessive dielectric grease can also cause the wire to pop off once it gets hot as well.