plugged cats?

[tillroot1]

Guys, I have been having some problems with my car, its the 6.2 and 6spd man, 2010. lately I noticed a cold condition miss, and then during acceleration it would miss in higher rpms, the first thought was a cracked spark plug. It has a janetty tune, arh longtubes,cats and mufflers and pipes, a cai cold air kit. the car has 42000 miles, I took it in to have new tires installed and the shop plugged the car in, a random miss code was thrown, the shop mech pulled a plug, very black, and brown, the electrode looked fine, pulled another and the electrode was worn clear to the insulator, pulled the rest and 4 out of the 8 had no tip exposed out of the insulator, it has been suggested that the cats may be plugged, my question is, can they be pulled and cleaned, they were spendy and I would hate to just throw them away, if indeed they are plugged. If they were plugged wouldnt the car throw a code stating so? I am not looking to throw any stones just fix the issues. Thanks, Ron Tilley

[yotaman96]

If they are plugged, it's because they failed and have come apart inside.

[lionssfan]

are you supercharged...this can shorten the life of stock a convertor. You can check back pressure with a gauge at the "pre" or forward 02 sensors. should not be more then around 1.25 psi. at 2000 rpm engine hot. if higher then look to be clogged convertor. also jiggle the muffler to see if it has loose convertor parts in the muffler or bang on it with your fist. You can pull the pipe connection and look at the inside of the convertor on the bank that that set the code or better the bank that had the bad plugs. also look at your post o2's (the 02's rear of the convertor)with a scan tool. if they show as much activity or cross counts as the front 02 then the convertor internals are gone/burned up. Typically the post 02's are slower responding with a good convertor when you look at it with a scan tool. Replacing the convertor if clogged or missing is what you will need to do. and replace all plugs of course. are the right plugs in the car the right ones? But first you need to look at why they burned up? tune?

[injector]

I've had this issue. I found out the parts inside the Cats went all the way to the stock mufflers when i went with magnaflow. what I've done (and that is my advise), custom made that area to fit resonators and remove the cats to lower the tone. when you the car is due for testing, remove the the resonator and fit hi flow cats (you have the pips already, so just get the hi flow cats and weld them).

[tillroot1]

Originally Posted by injector

I've had this issue. I found out the parts inside the Cats went all the way to the stock mufflers when i went with magnaflow. what I've done (and that is my advise), custom made that area to fit resonators and remove the cats to lower the tone. when you the car is due for testing, remove the the resonator and fit hi flow cats (you have the pips already, so just get the hi flow cats and weld them).

by removing the cats, will that adversely affect the cars computer? throw codes, and so on, I did think of doing just that, the whole thing is hard for me to grasp, the plugs are long life, the car is not old, not alot of miles on it, and so on, all I know is that I want to fix it. I would think the high flow cats would last alot longer for sure, 91 octane gas is all that I have access to here in my area, and that is all the car has had in it since new. Thanks, Ron Tilley

[Unobtainium]

The. Computer can be told to ignore the info from the secondary sensors, if it hasn't already.
As I mentioned in the other thread, I ve swapped bad cats to resonators for many customers already in 2012. It's a very common problem on supercharged cars. I always advise against cats now for those applications when I'm approached for custom exhaust.
If you need to pass a test once in a while, then do as suggested above and make the resonators remove able and replaceable with cats. v-bands work great for this.

[injector]

codes are easy issue that can be solved by tuning. Don't worry about it so much. This is better than going with direct pipes as your car will be loud even with stock mufflers and still throw codes.

[tillroot1]

Originally Posted by Unobtainium

The. Computer can be told to ignore the info from the secondary sensors, if it hasn't already.
As I mentioned in the other thread, I ve swapped bad cats to resonators for many customers already in 2012. It's a very common problem on supercharged cars. I always advise against cats now for those applications when I'm approached for custom exhaust.
If you need to pass a test once in a while, then do as suggested above and make the resonators remove able and replaceable with cats. v-bands work great for this.

so, if the cats are pulled off, what do I do with the sensors? unplug and leave alone? do they still need to be installed to the pipes? Thanks, Ron Tilley

[GMTool]

From what I have read, you really do not know for sure if one of your cats or both or niether one is plugged or damaged yet? I cant imagine that both of them failed at the same time. I would get under the car and hit them with a clinched fist and listens to see if I could hear any rattling sounds like the cats honeycomb is broken apart inside it. Or where your cats connect to your catback, take off the band clamp and take a look see. If your cats were plugged, your car probably has been running like crap, correct? Hard starting, poor acceleration, very hot, ect. I know you said it has had a cold miss condition, and your plugs look bad. Maybe the problem is something else.

[tillroot1]

Originally Posted by GMTool

From what I have read, you really do not know for sure if one of your cats or both or niether one is plugged or damaged yet? I cant imagine that both of them failed at the same time. I would get under the car and hit them with a clinched fist and listens to see if I could hear any rattling sounds like the cats honeycomb is broken apart inside it. Or where your cats connect to your catback, take off the band clamp and take a look see. If your cats were plugged, your car probably has been running like crap, correct? Hard starting, poor acceleration, very hot, ect. I know you said it has had a cold miss condition, and your plugs look bad. Maybe the problem is something else.

I will get under the car and try that to check, I do not know if the cats are the problem for sure, but that was suggested to be. It scares me to have 4 out of 8 plugs with the electroded burnt off, the engine temp has never been high, it starts the same as it always has, just the miss and loss of power. thanks, Ron Tilley

[lionssfan]

Take it to a reliable tuner shop. A dealer won't cover it if it's still under warrenty, because of the headers and cats as you probably already know anyways. You need to root cause what started the problem. Bad tune, many things could of caused a mis code? As soon as your miss code set that would of been the time to diagnos the problem. Because at that point did a mis cause the cats to go bad or if the cats went bad did that cause the plugs to foul. From the sounds of it you probable had driveablility problems for awhile, always best to take it in soon as possible.

first step find out condition of cats as mentioned above. if ok, replace all plugs and diagnose from there root cause of mis fire code could be many things...bad tune, plugs, plug wire, injector on and on. If cat is clogged and you don't have emission testing in your state. Then you could remove all inner material of the cats and replace plugs and install a tune with rear o2 sensor deletes. and root cause from there again. I don't know how handy you are, but looks like at some point your going to need a "reliable" tuner shop in your area to look at it. Your going to need a scan tool to diagnos at some point. I wouldn't cut corners on a tuner shop...go to the best in your area. good luck

[GMTool]

Originally Posted by tillroot1

I will get under the car and try that to check, I do not know if the cats are the problem for sure, but that was suggested to be. It scares me to have 4 out of 8 plugs with the electroded burnt off, the engine temp has never been high, it starts the same as it always has, just the miss and loss of power. thanks, Ron Tilley

Is the bad looking plugs all on the same side of the engine? If so, the cat on that side would be most suspect.

[tillroot1]

can anyone refer a competent tuner shop in the Billings Mt area?, that is the nearest city where I reside. Thanks , Ron Tilley