Short Life Catalytic Converter

[Lemming]

Greetings…

I am hoping someone can help me.

I have a 2005 Pontiac Sunfire, after receiving another P0420 code I am replacing the catalytic converter a second time in 15,000 miles (total miles on the car 103,000). The cat I just pulled off is quite discolored and appears burnt. It was pretty and new when I put it on at 88,000 miles. I have previously replaced the downstream oxygen sensor. The car does not burn oil or have any coolant leaks. I am getting fairly nice gas mileage, 31mpg. No other fault codes are coming up, either. I have no problems with acceleration or power. For the most part the car runs GREAT, just seems to be eating catalytic converters. I am in a state where I have to go through emissions inspections every two years, so I want to do everything the correct and legal way.

Other than replacing the spark plugs, is there anything I can do to extend the life of the catalytic converter?? I’m guessing that there is excess fuel not being burned during the combustion process?? I’m an old school “points and condenser” shade tree mechanic, so these error codes are fairly new to me. I appreciate any assistance or suggestions.

Thank you in advance…

 

[melsg5]

1. Have you tried using an air/fuel meter?
2. Did you install a brand name O2 sensor?
3. Did you install a brand name Cat?

 

[Lemming]

In answer to your questions...

(1) No, I have not used an "Air/Fuel" meter. Can you explain more about this device and how it is used??

(2) I replaced the downstream oxygen sensor with a "Bosch" Oxygen sensor.

(3) The catalytic converter was a "Davico" brand.

Again, thank you for your help.

 

[melsg5]

An air fuel meter functions like an oxygen sensor but it is not a permanent component of the car. Typically it is inserted into the tail pipe for testing.
I would recommend you try an OEM AC-Delco oxygen sensor.
I can't file any negative comments about the Davico brand of converters.
I would check to make sure you have no vacuum leaks, cracked hose etc.

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[Lemming]

I did have a cracked hose/intake resonator nipple. It is where the hose comes from the valve cover into the intake resonator above the throttle body. I think that may be some type of PCV system?? I did repair it (new hose and new intake resonator).

Perhaps, I didn't catch it early enough and it damaged the catalytic converter??

One more question.

Is it my understanding that the computer controls the amount of fuel sent into the cylinders for combustion?? If so, is there any way to lean it out or send less fuel for combustion??

Again, thank you...

 

[Zimgxp]

Short of a custom tune, the fueling can't be changed. Verify the air fuel ratio. It should be around 14.7 to 1

 

[Lemming]

OK... I have two more questions.

(1) I removed one of my spark plugs and went to my local car parts shop to obtain replacements. The spark plugs that were in the car did not cross reference to my Sunfire. So I purchased the correct AC Delco plugs and installed. Could the wrong spark plugs in the car have anything to do with the pre-mature failure of my catalytic converter??

(2) After waiting a week for parts, I put everything back together and connected the battery back up (I had disconnected it when I disassembled the previous cat and downstream oxygen sensor). Upon attempting to start, all the dash lights came on like normal, when I went to engage the starter to start the car, I heard a "click" and the dash panel went blank/dark, no starter engaged, no lights, nothing. I assumed it was something to do with a security mode?? So I came in and read the owners manual, but came up with nothing (I don't have a security system or security fob). Being a shade tree mechanic, I disconnected the battery and waited 30 seconds and re-connected it. The car started right up, I took it for a little test drive and it actually runs better. Was the first attempt to start the car some type of "passlock" or "security" lockout from being disconnected from the battery for a week?? I didn't get any security lights or any other codes or error messages. Is the car safe to drive or will this security thingy kick back in at a later date??

Thank you in advance...

 

[melsg5]

wrong plugs can create strange problems
it sounds like the first time you had a bad battery connection

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