Cat. Converter Questions?

[Ironhorse]

First off, I am not very knowledgeable about the cat. systems on vehicles. Wife and I have a '99 4 WD 5.7L Tahoe bought used 4 years ago, had 67K on it then, now has 108K. Outside of a couple issues has been a pretty good truck. Cloth interior, loaded and comfortable to drive. Just recently the "Service Engine Soon" has come on several times. Truck running fine, plenty of power, shifts smooth, all gauges reading good. Took the truck to a mech. friend I have know for years, scanned it and came up with "code PO430 catalytic efficeiency low bank 2" . He suggested replacing the right bank cat. converter. Several people I have talked to said the cat converter needs replacing BUT they don't "just go bad". Was also told DO NOT install a universal single cat. Spend a little more and go with a "direct fit" style for a lot less computer issues on the Tahoe. To my knowledge the plugs, cap and rotor has never been changed. Planned on doing plugs before this came along. Checked with my wife's GM parts man cousin, best he can do is $865 for a GM cat., local parts house can get a Walker direct fit cat. replacement for $420 plus my install costs. What to do? Do I have other problems than the cat. or will that solve my problem? Kansas does not have emissions testing mandate presently but may be coming in future from reading and listening to the news due to south centralo Kansas ozone and air issues. Bad timing since Santa doesn't need this at this time of year. Sorry for the long post but know very little cat. and emmisions stufff and don't want to spend $$ on something that won't fix the problem.

[kaycee]

Wow they like there cats,I think you could shop around and find some new cats for under $250.Then just cut your old ones out and replace it's not really rocket science.I gutted mine on my 97 HOE and bought some 02 simulators to fool the light.I don't think you can get them anymore 02 sims. but you can still gut them now or take out and run straight pipe till you get the $$

[Boog]

Been through the same issue with my 97 Burb. The cat efficiency is just below the optimum so it sets the light. The truck still runs fine. I wasnt' ready to spend big bucks for a new cat so I used another trick to stop that annoyance. You use one of the deep spark plug non foulers in between the rear O2 sensor and the pipe. You have to drill the hole in the non fouler just a big larger to clear the sensor tip then just screw them in. What it does is it moves the O2 sensor an inch or so out of the exhaust flow. Think of it as a spacer. The non fouler screws into the exhaust pipe then the sensor screws into the non fouler. Stock appearing and I've been running this on mine for 5 years now and no more codes.

[JohnC]

Originally Posted by Boog

Been through the same issue with my 97 Burb. The cat efficiency is just below the optimum so it sets the light. The truck still runs fine. I wasnt' ready to spend big bucks for a new cat so I used another trick to stop that annoyance. You use one of the deep spark plug non foulers in between the rear O2 sensor and the pipe. You have to drill the hole in the non fouler just a big larger to clear the sensor tip then just screw them in. What it does is it moves the O2 sensor an inch or so out of the exhaust flow. Think of it as a spacer. The non fouler screws into the exhaust pipe then the sensor screws into the non fouler. Stock appearing and I've been running this on mine for 5 years now and no more codes.

That's a great tip!!!

[bwood]

My dad just went though this on his 99 Tahoe. He paid right around $1k. There are two cats on these. The actual y pipe is one part that contains both cats, thats why the cost is so high. Personally, I would try and go with the OEM. I have had poor luck with aftermarket universals on newer OBD II vehicles.

Here is a Catco model from Summit:
http://www.summitracing.com/parts/CTO-9333/

Here is a Walker model from Summit:
http://www.summitracing.com/parts/WLK-50410/

Those who have told you that they don't just go out are correct. Generally its from other issues like fouling from buring antifreeze, oil or carbon build up. But, if it spends a lot of time idling or moving slow, this cuts the cats life. Have the truck checked out to make sure something else isn't going on. Are you loosing oil/coolant with no visible leaks?

[Ironhorse]

Boog, That plug fouler tip sounds promising. By drilling the hole for the sensor will that not mess up the inner threads of the non fouler? Guess I'm not sure how the sensor would then screw into the non-fouler and then the non-fouler into the cat. converter. What am I missing, as I said at first, I'm not very knowledgeble about cat. converters. I like the idea much better than spending a grand for a OEM converter.

[Boog]

No. I forgot the exact bit size but it's smaller than the internal thread size of the non fouler. It needs to be just big enough for the sensor tip to clear. Just out of habit I put antisieze on the threads too. It has worked great for me.
I didn't mention it but there are a couple of sizes of nonfoulers. You will want to get the deep one. I guess you could head to the parts house and have them pull out the correct sensor for your truck and both the non foulers and you can easily see which you will need. Like I said it's worked great for me all this time. And it's easily reversable if you choose.

[Jacfourteen]

Does the truck run rich (gas smell in the exhaust) or have a misfire? The reason I ask is if excess fuel gets to the cat it burns inside the cat and overheats it destroying the honeycomb. From what I've seen this is the most common cause for a bad cat. Like mentioned above the cat may not actually be bad, it is just not dropping the O2 reading as much as the computer would like to see. One other thing is a bad O2 sensor could also trick the computer to think the cat is bad. Just a few things to think about. So far I like the plug anti fouler idea.

[Ironhorse]

The Tahoe doesn't seem to run rich at all. Tail pipe is clear, not sooty or black. Exhaust doesn't smell "gassy". I did put in a container of fuel injector cleaner before a fill up, took it on a 325 mile round trip to Greensburg, (162 miles one way) and back, service engine soon light never came on. Ran fine at 65-70 (couple times near 80 passing vehicles). Wife took it to work today and reports the light still is off. Would the injector cleaner possible done some good? ???? About 3 weeks ago I did add some coolant since the over flow tank was down about a 1/2 quart. First time I've added any in many many months. Since then coolant is still up to level. ???? Guess I'll continue the watch and see what develops.