Stumble driver side overheating cataytic converter

[MuRCieLaGo]

Dodge Viper 1994 no A/C

Today, I started the car and realized that the driver side has a light exhaust stumble. Catalytic converter is also red hot.

Wires seem to be installed properly (wow diagram in FSM is so bad).

Any clue where I should start this project? I'm pretty sure that the problem is there since I own the car (and drove about 1,600 miles in that condition).

No CEL.

Thanks!

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[GTS Dean]

Plugs not firing will load the cat with unburned fuel and cause them to run hot. The car is 25 years old, and the cat substrate could be plugged.

[MuRCieLaGo]

Plugs not firing will load the cat with unburned fuel and cause them to run hot. The car is 25 years old, and the cat substrate could be plugged.

Oh well, it was much easier. 5 and 7 plug wires were reversed. I should mark the wires one by one... Idle and overheating cat are now fixed.

Can I ask another question? If I cut that cat and weld a straight pipe instead, will it throw a CEL? Is the engine going to run badly? I just want to cool down the side sills.

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[Ross L]

No CEL, will run better and rocker heat will be a non issue.

[MuRCieLaGo]

No CEL, will run better and rocker heat will be a non issue.

Alright great!! Side exhausts are now at the nearest welding shop!

[GTS Dean]

It's gonna be LOUD. I would strongly recommend HF cats when coupled with aftermarket mufflers.

[daveg]

It's gonna be LOUD. I would strongly recommend HF cats when coupled with aftermarket mufflers.How much louder is it going is it going from Stock cats to HF's? Particularly on a Gen II? with rear exit? I know, a little off topic...

[dave6666]

I've had side exhaust on my Gen 2 for over 10 years now. Belanger headers + HF cats + mufflers = loud. Belanger headers + no cats + mufflers = very loud. Extremely loud at WOT.

Choose wisely.

[MuRCieLaGo]

Hmmm, I really hope it won't be LOUD. All my cars are relatively quiet and I like it that way (I also own a ZR-1, a C63 and a RX-7).

I'm keeping stock exhaust manifolds and mufflers...

[Ross L]

If you have stock mufflers it will not be that loud at all.

[MuRCieLaGo]

If you have stock mufflers it will not be that loud at all.

I hope you are right! The main reason I'm doing this is temperature, I'm sending my side sills for a respray because they had paint bubbles, especially near the cats.

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[Ross L]

I think you'll be surprised by the lack of heat once you delete the cats.

[GTS Dean]

You do not have stock mufflers in your sills right now.

Cats don't start their oxidation/reduction cycle until they hit around 600F operating temperature. The computer will vary the richness (thus the temperature) while in closed loop mode so the cats will operate properly. The OBD-II JTEC controllers on the '96+ cars have downstream O2 sensors to monitor the efficiency of the convertors.

[JonB ~ PartsRack]

Your cats are officially Toast.

HF Cats R Us

[daveg]

Your cats are officially Toast.

HF Cats R UsJon, I guess Ill ask you the question.. How much louder going from stock cats to HF with rear Exhaust and Borla 3" (no rear mufflers) on Gen II ?

[Old School]

Alright great!! Side exhausts are now at the nearest welding shop!
It's sometimes difficult finding a muffler shop willing to remove cats.
Also, you could replace those cats with mufflers to keep the noise down.

https://www.summitracing.com/parts/wlk-24236?cm_mmc=ppc-google-_-search-_-brands-_-keyword&gclid=EAIaIQobChMIrMfI-5zz4AIVQrnACh0dkQlQEAAYASAAEgKK9fD_BwE

[MuRCieLaGo]

You do not have stock mufflers in your sills right now.

Cats don't start their oxidation/reduction cycle until they hit around 600F operating temperature. The computer will vary the richness (thus the temperature) while in closed loop mode so the cats will operate properly. The OBD-II JTEC controllers on the '96+ cars have downstream O2 sensors to monitor the efficiency of the convertors.

I thought these mufflers were stock...


Your cats are officially Toast.

HF Cats R Us

I don't know, after I fixed the issue causing the overheat (driver side only), temperatures were the same on both sides.


It's sometimes difficult finding a muffler shop willing to remove cats.
Also, you could replace those cats with mufflers to keep the noise down.

https://www.summitracing.com/parts/wlk-24236?cm_mmc=ppc-google-_-search-_-brands-_-keyword&gclid=EAIaIQobChMIrMfI-5zz4AIVQrnACh0dkQlQEAAYASAAEgKK9fD_BwE

Where I live, we don't have annual inspections or anything like it and police can only run visual inspections regarding emissions. That is why garages don't really care about that.

[MuRCieLaGo]

Okay, so I had the cats removed and replaced by straight pipes. Cats visually seemed still in good shape.

Review:

Sound: nothing to worry about. I had my ears tested 3 weeks ago and they're in good shape. I know it is impossible, but in fact it seems like it is quieter. For sure sound is not an issue.
Smell: noticed a strong smell in the garage quicker than usual. Of course, all doors were closed. Everything was OK once a door was opened.
Temperature: I'm a bit upset. I was expecting better results. I had 525°F with the cats, and now with cats removed it went down to 478°F.

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[Pauler85]

I had removed my cats and installed thrush bullet mufflers. Definitely louder.
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