driving with clogged cat.....issues?

[SEEEEYA]

think I have a clogged right side cat, hit it hard it falls on its face at 3000 to 4000 rpm, slow acceleration and it does not do it. have replacement hi flo and cat back on order, is it ok to drive the car this way??side sill seems very hot but honestly never checked it before the problem started, no CEL, engine temp gauge is normal, do I have anything to worry about when I drive it? just being gentle?its hard to leave it in the garage now that spring has sprung

 

[SlateEd]

Mine started out like that a few weeks ago... exactly what you described, choking on any throttle around 3000 and up. The stock SRT cats are ceramic primary, metal secondary, and the ceramic bits and pieces had completely clogged the metal foil in the secondary. It got worse RAPIDLY so I put it away until I could install new cats. - I can't imagine ANY exhaust would have gotten out the passenger side if I drove it much more... That much back-pressure can't be good.

If I were you now, I would avoid going too far with it.

 

[uvbnbit]

No CEL's? Seems there'd be some code

 

[mjorgensen Woodhouse]

If the cat was plugged as above there should be a CEL. If there are already aftermarket cats and a PCM tune to eliminate it then that is another story. Either way if that is what it's doing I would NOT drive it, the excess heat will damage other things in the engine.

 

[SEEEEYA]

no CEL "lately" have had a "down stream passenger side O2 sensor code" but the last couple days it has been off, so that might be a direct result of the plug huh? I was going to change it with the exhaust, BUT why does this happen with 4000k miles on the car??and it happens, from what I read, to a lot of Viper owners, driving over 30 years this is the first time I've seen this with one car. I can see if you run it rich with a SC but stock is stock, and no mouse steak smell came out so I know no nest was in there. so who knows. I will check out the flow to compare today just to see how bad it is, but the side sills are very warm

 

[dester243]

I would try to not drive it. The manifold and pre clog area exhaust gas temps will soar. I have seen manifolds (not on a Viper particularly) glow red hot. I personally wouldn't chance it. Park it until repairs are made.

 

[slysnake]

Don't drive it. I would worry about the back pressure and heat.

 

[plumcrazy]

Do not drive it ! heat will back up into the engine and you can blow it up. dont ask me how i know.

 

[Viper Garage Elite]

His second question is why the cat is clogging so fast. This seems rather quick to me . Any answers out there.

 

[plumcrazy]

bad tune, couple of dead plugs/wires, way too much fuel ?

 

[SEEEEYA]

MY next problem is it is 8 miles to my friends house who has a 4 post for my swap out, can I be gentle??

 

[SEEEEYA]

there is no crossover before the cats right? so if its running "plugged" is not an issue right? starting yes but not totally plugged??

 

[dester243]

I wouldn't chance it. Cats are both before the cross over. Sometimes the clog gets worse as it gets hot. A tow might be cheaper in the long run vs driving and damaging something.

 

[SlateEd]

His second question is why the cat is clogging so fast. This seems rather quick to me . Any answers out there.

the clog can get worse quickly because once the ceramic primary cat starts to crumble even just a little bit it can't hold itself together and the crumbling goes rapidly to total collapse (especially under pressure from exhaust output) The ceramic chunks and dust start to fly downstream and can actually MELT into the front end of the secondary... I just took mine apart 2 weeks ago and that's exactly what I found. Mine went from running okay to stalling out at 1500rpm in 1st gear within 15 minutes of driving. I consider myself lucky that i didn't damage anything.

You can see in the scope looking into the cat pipe, past the elbow and into the front of the secondary cat. The white-ish chunks are pieces of ceramic melted onto the front of the metallic secondary... that amount of clogging was enough for the car to practically stall out in first gear at 1500 rpm

the second pic is the crumbled bits that fell out of the pipe immediately after I took it out of the car.

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[ViperTony]

Ed how long have you had your ceramic cats? These are aftermarket correct?

 

[SlateEd]

Ed how long have you had your ceramic cats? These are aftermarket correct?

the ones pictured above that fell apart were the original stock ones. Stock SRTs have a ceramic substrate in the first cat and a metal substrate in the second one.

I changed them out for RandomTech ceramics. (that's just 2 weeks ago, but so far so good... a little louder for sure, much cooler side sills)

 

[Viper Specialty]

Stock cat failures are fairly common on Gen-3 & 4. The reason is that the ceramic primary starts to fail more easily than the metallic primaries used in previous generations. Once a cat starts to fail, it becomes a runaway condition. The higher exhaust pressure registers as a lean condition as far as the ECU is concerned due to the way an O2 sensor operates, and it adds more fuel to compensate. The extra fuel increases converter temps, and the converter failure accelerates, leading to higher pressures. It is a domino effect that can take place very quickly. Unfortunately, the only way for an ECU to "see" this condition would be to have an exhaust back-pressure sensor, which the Viper of course does not have. Otherwise, the ECU is being "tricked" by the O2 sensors, and has no idea what is really going on.

We recommend metallic cats in all performance installations. They tend to be more robust with a higher core melting point and more resistance to thermal shock damage as well as physical shock damage.