Not necissarily. If he has unburnt fuel being evacuated into the cat, where it is then being burned off, it will cause his pipes to glow. That is from a rich mixture in which more fuel is being pumped in than air and it isn't burning properly.

If it were only happening on one side I'd say check your plugs, but given it is both, I'd say your tuner went a little rich and your cats can't handle it and are clogging. As they burn more fuel, they get hotter and your engine just keeps feeding it.

 

Your tune file looks like its running CL... so it should be trimming the AFR to stoich.

Unburnt fuel is getting to the cats, causing cats to glow red hot like that... are you getting misfires...?

Running rich won't heat up the cats like that as long as the fuel is being burnt.

There is a big difference between a rich burn and unburnt fuel.

 

Leaner means hotter combustion chamber temps (until there is not enough fuel to burn)...

it also means hotter catalytic temps, if the temps go sufficiently high the PCM enters cat overtemp protection mode where it applies extra fuel... but in these cases the fuel is being burnt, and the cats don't glow red hot...

When fuel is not being burnt (e.g. consistent misfires) then the raw fuel is being ignited by the catalyst which causes a great amount of heat...

The catalyst normally deals with a mixture of HC/CO/CO2/NOx gases rather than unburnt HC/fuel.

 

When I decellerate (while in gear), the car backfires every so often. But I thought that was due to a lack of backpressure.

 

I mean misfires while running/driving/cruising/accelerating.

 

Take the word "backpressure" and delete it from your vocab for starters.

 

Hotter chamber temps also means hotter EGT temps. FI cars run 10.5 - 11.5 AFRs and don't have glowing cats after every track event.

I'm not saying its impossible that unburnt fuel could light up a cat, but I doubt that would be the only factor... something is making the cat very inefficient... perhaps poor exhaust flow/routing + a rich condition... or quite simply, a lean condition.

 

I do not notice any misfires during acceleration anymore. It used to, but I tracked it down to a loose ignition wire. I'll check the wires again. I have those ignition wire "heat wraps" on them, and sometimes it's hard to get a good seal.

So I don't sound ignorant in the future, will you please forward me a link to more info on "backpressure"? I used to own an '84 GSL-SE RX7, and it needed "backpressure" to open up valves to work correctly. My other car is a turbo Eclipse and was a twin-turbo Rx7, and I was always told to eliminate as much "backpressure" as possible to make the turbo(s) work more efficiently. I know a modern GM V8 is entirely different (and more efficient) than an '84 13B, 93 13B-REW, and 4G63T, but the topic of backpressure always comes up.

 

I have the END ALL solution to your worries:

















GET RID OF THE CATS AND QUIT BEIN' AN OLD GEEZER ABOUT THE NOISE!!

 

stop talking

 

To the first, with a misfiring, you could have fouled your 02 sensors with a bit of carbon. Not so much that it'd read really bad, but enough. Might be worth it to pull them off just to be sure.

As for the second, back pressure is used in turbo/super applications and two stroke engines. 4 stroke engines are typically cammed and that regulates the opening and closing of valves.