I know there have been some previous posts about this issue, but I just want to know what some of you have done in the past as I'm sure you've run in to this at some point or another. I've already run through codes and it is definitely the Catalytic Converter. My gas mileage has decreased so I know they're faulty and it isn't a cold weather/warm weather thing.

I have a fast intentions exhaust system.

What do you all recommend? I'm thinking of just scheduling an appointment with my exhaust shop to take a look and see what needs to be done.

Don't mean to repeat posts, but your help would be appreciated.

 

Replace 'em with hfc's.... will really open up your exhaust

 

How are you sure it's the cats and not a bad sensor? What are you codes? Gas mileage is changing due to the code telling your long-term fuel trim to make adjustments. Let me know what codes you getting and I can better diagnose for ya.

 

Get FI RHFC's to match your exhaust.

 

I forgot the exact code number, Robert, but i think it was 0420. Got the codes at a actual shop and the guy told me sometimes the sensor gets messed up due to going from colder weather to warm weather and he cleared it thinking it may not come back, but if it does to maybe consult with an exhaust shop.

Getting HFCs is something I can consider

 

OK... I would first diagnose the reason for the code, P0420. I'm all for getting HFC but shotgunning parts doesn't fix the problem. You could add the HFC and still have the code due to a bad sensor.

Catalyst converters just don't randomly fail. And it is an expensive part to replace. Little background on the sensors; There are two sensors in the exhaust stream; a pre-cat and after-cat. The pre-cat is more of a AFR, or wideband sensor. Its purpose is to make sure the engine is getting the optimal air/fuel mixture for factors like power, gas milage, epa regulations, etc... This is not an O2 sensor. The after cat sensor, most know of and shotgun parts at it (replace without diagnosing) is an O2 sensor. Its purpose is to make sure that the catalytic is working efficiently. Basically burn all the bad gases the tree huggers hate. When it detects the cat is working it tells you ecm to add or remove fuel. That is why you'll see changes in your gas milage. Reason it add or removes fuel are; bad cat obviously, exhaust leak (before the sensor*), too much or not enough fuel delivery (leaky or stuck injector), or even the air/fuel mixture is getting burned properly during combustion. Reasons could go on forever.

Basically though you need to diagnose why you have this code. As mentioned on that link a scope tool is best. It tells you what exactly is going on. It is what I would recommend before just changing parts.

 

I really appreciate the tips. Talked to a respected shop near me and will be getting things checked out tomorrow.