smoking sill cat failure????

[mykes]

So im at the track and my left sill is smoking(towards the front of car right behind cat).I get home take sills off and no evidence of melting?I think the cat has failed,and im going to cut the outer cats(both sides)out,and replace with straight pipe to muffler.Any problems doing this,looks a little tight but think i can weld the pipe in without removing the whole unit?Should i remove them completely?What size is the pipe,i think its 2 and a half inch?Any tips, problems,anyone could offer would be helpful and yes i know it will get louder ps already have 08 exhaust on it. thanx in advance Myke

 

[plumcrazy]

what year and mods do you have ?

 

[RTTTTed]

You can't just remove the Cats without getting a CEL. You need to build a couble non-fouler holder of buy simms to replace the rear 02 sensors.

What happens is that the Cat protection program will measure no difference between the front and rear 02 sensors and it may trigger a fuel dump to "save" the Cats from overheating. The extra fuel may cause a "limp home mode"?, or make it so rich that it loses power or various other issues. Sometimes these cars will even run for a short while without change.

So it goes on the previous 3 Gens of Viper at least.

Ted

 

[steve911]

the rear cats on a Gen 3 can be gutted or removed without getting a CEL as the secondary O2 sensor is in between the primary and secondary cat, thus no measurement of its presece or deletion.

I gutted my secondary cats. Less hassle than taking it to a muffler shop and short of taking the exhaust apart, it looks stock

 

[mykes]

It's an 05. How do you gut them?Stock k&n air filters.

 

[RTTTTed]

Cut them off, use wood drills, chisels or whatever to bust out the material inside the Cats. Re-weld. Or just chop out the rear cat, weld in a straight pipe and leave the front Cats?

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Different car (Stealth TT) but same pricipal.

Ted

 

[steve911]

For a Gen 3 car it is pretty easy. (have done 6 sets already). Assuming the side sills are off,
Step 1. Unbolt muffler from cat assembly.
Step 2. Unplug secondary O2 sensor from vehicle harness.
Step 3. Remove clamp holding convertor assembly from exhaust manifold and remove cats from car.
Step 4. You'll notice that the guts of the secondary cat are visible from the end of the pipe where the muffler was bolted to. Using a 1" wood spade bit (my personal favorite) and and electric drill or strong battery one, start drilling into the converter guts, periodically dumping out the results of your drilling. I also use a long needle nose pliers to rip out the loose pieces. There will be dust generated in the operation. I use a dust mask to protect myself. It takes about 45 mins a side to remove the guts. After all is removed stick a vacuum down the pipe and remove the loose pieces that may remain.
Step 5. reinstall pipe into vehicle and reattach band clamp at exhaust manifold (some what loose until entire exhaust reconnected)
Step 6. Re-attach muffler and tighten system.
Step 7. Re-connect O2 sensor plug to vehicle harness.

re-install side sill.

That about all there is to it.

 

[mykes]

Thanx Steve,it almost sounds easier to weld in new pipe.Do the cats clean up smooth on the inside?Do you think they run as cool as the staight pipes would?

 

[steve911]

they do clean up smooth inside. I would imagine no temp difference between welded straight pipe and original cat shell.

The reason why I did it my way was to save the bucks (stainless pipe isnt cheap ) and I would never just do regular exhaust pipe, it still looks stock and I did it in an evening.

 

[mykes]

Thanx,and the gutting begins.

 

[Black Moon]

I don't want to hijack your thread but I have a question. I have a Gen3 with headers and no cats. O2 sensors are in place and I've never had a code. It has a stock PCM. Does this make sense? Any input would be appreciated.
Sal

 

[RTTTTed]

Are you still getting 22mpg (US)? Sure you removed all 4 cats? I'll ask Larry Macedo (he's who I ask when I want a second opinion).

The second 02 sensor program is to keep you from removing the cats and keep the cats from overheating. Comes on all the modern cars I've looked at. Larry Macedo was telling me that some of the pickup trucks (Hemi) don't throw a code when you gut the cats. I bought a Predator and then had to send them an email to get the rear oxy sensor program deleted from my ECU. Then I had to leave the 02 sensors plugged in so that the "heater" code CEL doesn't set.

Ted

 

[RTTTTed]

I don't want to hijack your thread but I have a question. I have a Gen3 with headers and no cats. O2 sensors are in place and I've never had a code. It has a stock PCM. Does this make sense? Any input would be appreciated.
Sal

Larry Macedo said, "Another thing to consider is that as long as the 02 sensor is connected and in the stream, it may not throw a CEL. Additionally, mechanical sims like spark plug anti-foulers can be used to limit the amount of flow to the 02 sensor."

Ted

 

[Black Moon]

Are you still getting 22mpg (US)? Sure you removed all 4 cats? I'll ask Larry Macedo (he's who I ask when I want a second opinion).

The second 02 sensor program is to keep you from removing the cats and keep the cats from overheating. Comes on all the modern cars I've looked at. Larry Macedo was telling me that some of the pickup trucks (Hemi) don't throw a code when you gut the cats. I bought a Predator and then had to send them an email to get the rear oxy sensor program deleted from my ECU. Then I had to leave the 02 sensors plugged in so that the "heater" code CEL doesn't set.

Ted

No cats. B&B headers and exhaust. Watch, the next time i drive it the ck engine light will come on. Don't know about the mileage but it runs great. I recently replaced the PCM and its clean too. Should I invest in a set of sims? Are they expensive? By the way, they make a Predator for our cars?

 

[mykes]

All done,thanx Steve.It was a little bit more work than i thought, but its done.

 

[steve911]

Glad you made it through.... You have to admit though, it really good to spend some quality time with the car.

 

[mykes]

Oh yeah a good time was had by all.

 

[Rizzo]

Hey bud. It was great to meet you at the track. I had a great time. You should pull your other cats out and just get the SCT from Viper specialties. Gives you a little more mid range power and gets rid of the decel popping. Too bad we didnt get to do some runs together. Next time.

 

[RTTTTed]

I don't think they make a Diablo Predator for the V10. My Predator is for the Wife's Hemi pickup.

Ted