I have avoided replacing my bad cats ever since I bought my car 3 years ago. I was able to do this because I live in New York and the emissions test allows you to have one system not checked in. I would reset my codes then drive it until all the systems would check in except for the cats then go get it inspected. This works because the cats are the last system to check in. I now live in Va and will eventually have to register my car here. I talked to a mechanic and he said all the systems have to check in in Va for it to pass. Does anybody know of a way to trick the computer to think that the cats are ok? I have heard that some people have had success by putting a washer on the back 2 O2 sensors. This pulls the sensor out a little and they see less of the flow. Which allows the cats to check in OK. Any info would be appreciated. Thanks

 

If your cat(s) are bad they should be replaced. When they go bad they either will crumble to pieces and rattle and be inefficient, or they get clogged with carbon and increase backpressure-which can be very harmful to your engine.You probably already knew that, but I guess if they were clogged bad enough you would certainly notice it during engine operation... You can get cheap universal cats and have the flanges welded on to fit. A bad rear 02 sensor will throw a cat code/CEL too. If you are in a bind I guess you could try the washer method, but a spark plug non fouler would probably work better- if it fits- dont know what the clearance is like on the 2.8 cats.

 

My cats are only not reducing emission properly. I dont care about this because the codes comes in when I am lugging it or the car is idling, and that is when the emission are highest. So overall I think my cats are working fine. What is the "spark plug non fouler" method. I have never heard of that. Thanks onepoint8tee

 

A lot of people use them for the rear 02so they dont get a CELwhen they put in a test pipe. You can get them at autozone or advance autoparts. The brand name is HELP! There are two screwed into each other in this pic from when I put in my test pipe:

 

Thanks onepoint8tee. A pic is worth a thousand words. So that is how you 1.8ers get away with no cats very clever. I guess I would have known that if I wasn’t a 2.8 noob. Why do you have 2? I would assume the farther away the O2 sensor is the less changes in the flow it sees. Basically it’s a glorified super washer.

 

Well the rear 02 sensor is basicalyjust a tatle tale for the front 02 sensor/cat and has no affect on performance, etc. So its best to take it as far out of the stream as possible without making it so NO activity is detected. Ive still had a couple CEL's for no activity, but not often. Id rather have an occasional CEL by having it further away from the stream than to have a constant CEL by keeping it tooclose.

 

I will give it a shot in a couple of weeks when Im at my parents house. No place to do it in my Apt complex. I will post back with my results. Thanks again onepoint8tee

 

I'm about to do this to my HFC with just one, though... if I keep getting CEL's I'll add another. Good thing it's so easy to get back there, eh!? [:@]

 

Its semi-easy with the test pipe, probably not so much with a hfc since its probably a little bulkier.

 

a HFC wont make any difference because that's what its designed for ( its a high flow catalytic converter ) but its still restrictive and a power lose