slight sulfur smell with new converters

[MC80]

I recently bought an 96 lx450(115k miles) and got check engine code PO420. After testing the O2 sensors and finding the two waveforms were identical, I replaced the Catalytic Converters. It's been a couple of days and the CEL remains off, but now I notice a slight sulfur smell coming out of the exhaust. Now I'm worried that I have some other problem that made the old coverters go bad in the first place. I just checked all six plugs and they seem to be firing well. I use Shell gas so I don't think it's that. Any ideas what could be wrong and what to check?

Thanks,
Brian

 

[cruiserdan]

A sulfur odor is usually a result of the fuel blend as opposed to the cats. Try a different fuel to see if the odor changes.

 

[elmariachi]

A sulfur odor is usually a result of the fuel blend as opposed to the cats. Try a different fuel to see if the odor changes.

If switching gases doesn't help, you may still have an oxygen sensor problem. The sulphur/rotten egg smell happens when the fuel mixture changes from lean to rich, causing the catalytic converter to release its stored sulphur compounds. This is why you smell it on cars in front of you under heavy acceleration or climbing hills. I wouldn't worry too much until it spits another code.

 

[MC80]

Thanks guys. Yeah, I have a feeling I might be running a little rich because of my MPG(14 on freeway). I'd like to try and correct any mixture problems because of the price of fuel and I don't want to burn up my new converters. Does anyone know if O2 sensors slowly go bad and get out of calibration or is a good/bad sort of deal. I'm not getting any check engine light on the sensors, but what else could make it run rich? I think my temp sensor for mixture is working because my exhaust doesn't smell really rich, like when you first start a cold motor.

Thanks,
Brian

 

[elmariachi]

but what else could make it run rich?Brian

-Injector Leak, Blockage
-Mass Air Flow Meter
-Engine Coolant Temperature Sensor
-Ignition System
-Fuel Pressure
-Gas Leakage from the Exhaust System
-Open or Short in the Oxygen Sensor or associated wiring
-Oxygen Sensor Defective
-Engine Control Unit

Go here for more detail:

http://www.4x4wire.com/toyota/4Runner/tech/OBDII_ECU/