pethog Posted December 30, 2008 Share Posted December 30, 2008 Greetings all. Replaced exhaust in Aug 08 with custom system. Car ran great, MPG was good. Cat failed last week, blocked. Had to remove O2 sensor for car to run. I want to try and figure out why it failed and what to check before(and if ) I replace it. Codes list O2 sensor and EGR valve. Sube mechanic suggested EGRs don't fail but solenoids do. (My Chiltons show the solenoid as seperate- SMPI) Is this likely? Any suggestions of what else to look for? CMP sensor etc? Thanks for any suggestions, Happy New Year! Pethog in Toronto Quote Link to comment Share on other sites More sharing options...
Pontiac6KSTEAWD Posted December 30, 2008 Share Posted December 30, 2008 To much oil bypass can create a sooty deposit on the Cat. Which in turn causes it to fail. From my understandings, this is why Sub has a dual cat system. So there isnt as much oil buildup, and the cat can heat up and burn it off, befor it gets burned on.. Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted December 30, 2008 Share Posted December 30, 2008 Does the car run too rich? Alot of cat failures are caused by this. The egr code may be from the plugged up cat. That cat sure didnt last long. Quote Link to comment Share on other sites More sharing options...
Skip Posted December 30, 2008 Share Posted December 30, 2008 somebody tried running leaded Avgas? Quote Link to comment Share on other sites More sharing options...
pethog Posted December 30, 2008 Author Share Posted December 30, 2008 Hi: Car doesn't/didn't burn a lot of oil, or smoke; passed its emissions testing ok. Oil pressure is down below 50% on the dial! Could that indicate "blowback" Worn rings? It's only done 250 K (130M) Same for gas. Mileage was good. Didn't smoke! That's why I was wondering what would cause it to run rich. I put a new fuel pump on in the summer. Seems to be OK. Would it help to cut the cat open, see what it looks like? Thanks Pete Quote Link to comment Share on other sites More sharing options...
Yo'J Posted December 30, 2008 Share Posted December 30, 2008 Slipped timing belt? 130K is time. Carbon blocking egr in manifold? Quote Link to comment Share on other sites More sharing options...
DaveT Posted December 30, 2008 Share Posted December 30, 2008 (edited) Codes list O2 sensor and EGR valve. Sube mechanic suggested EGRs don't fail but solenoids do. +1 for the Sube mechanic. Here is my fix for the EGR code: http://home.comcast.net/~davidtief/solenoid.html If the O2 sensor was going bad, it can cause the mixture to be off, and kill the cat. I had that happen once. When this partial failure happens, the ECU doesn't recognize it as a failure, and no error code shows. Edited December 31, 2008 by DaveT clarity Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted December 30, 2008 Share Posted December 30, 2008 Was it throwing codes befor the cat failed? Quote Link to comment Share on other sites More sharing options...
pethog Posted January 2, 2009 Author Share Posted January 2, 2009 Thanks for the help guys. Timing belt was changed 25K ago, there was a code come up a while back from the original failed cat in August just prior to getting the new one installed. I think we're going to cut off the cat and check it out, replace it and the O2, check the egr. DaveT- your egr fix looks great. I am constantly amazed at the knowledge and experience you all have!. I guess I just didn't get my hands dirty enough when I was a kid. The parts guy, Howard, at the local dealership was a former mechanic, and for years had shared his time and experience when I went to buy parts. He passed away a year ago. Now they don't even have the shop manuals for the loyales..... Silent lifters in 09! pethog in Toronto Quote Link to comment Share on other sites More sharing options...
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