Hervey "Performance" Cat Glowing Red

[sdg3205]

Has anyone else had trouble with Hervey's bolt on performance cat?

I bought this one off Billy. It's brand new, but glows red constantly. I was down at DMC NW, and Toby and John saw no reason why it should be glowing. The timing was checked and is at 12 degrees, the mixture is spot on and John ran an injector test, even replacing a dodgy one.

The exhaust doesn't smell rich at all. Temperatures on the manifolds are between 350-450F IIRC but the cat glows red at almost 1000F.

I don't know much about cats, but there was some speculation that perhaps its not a true 3-way cat, or that the insides are toast and being restrictive.

[jmettee]

I've had mine for about 4 years now....no problems before cams or after (currently at about 17 degrees advance if that even matters). I think glowing CAT usually means the car is running really lean (or is it really rich?). Beyond fuel mixture issues, I have no other ideas.

[Ron]

A rich or lean condition can cause it -- it depends on "where". Keep in mind that when you checked the mixture, you were seeing the output of the entire engine.

It takes extra fuel AND air to make the cat glow. Without oxygen, extra fuel will (basically) go on out the tail pipe (and you will smell it) and the cat will not glow. (This can actually cool the exhaust!)

Causes:
If you have extra air (a vacuum leak) that does not get to all cylinders, the system will add fuel to all cylinders, because it thinks they are ALL burning lean -- The ones w/o the extra air will burn rich and others will burn lean...the overall mixture will have extra air and fuel, causing the cat to glow as the mixture finishes burning inside the cat.

If you have extra fuel (say, because of bad injector), the system will cut back fuel on all cylinders -- Similarly, some cylinders will burn rich and others lean, and again you have extra air and fuel in the cat...

If your timing is off (usually late), the mixture does not have time to burn before being pushed into the exhaust -- same result.

All the same result as when you have a bad plug/wire/other ignition problems, the most common cause of a glowing cat.

Other causes I can think of are: very lean overall mixture, bad fuel, and bad converter (least likely here, if it hasn't been abused physically or suffered the above conditions for a long time).

Hope this helps...