clogged Cat converter

[camarokidd10]

Ok, here's the scenario: on my car I have a borla cat-back exhaust, whisper intake lid, K&N filter, and slp ram air kit. one day my car starts acting up on me...such as I hear a clicking coming from the engine at high RPM's and the car wont shift unless I take my foot off the gas. [img]graemlins/omg.gif[/img] and I'm thinkin to myself what the hell! I take it to the dealership and they say that its the air/fuel ratio, that the engine isnt supplying enough fuel to burn all the extra air coming in from all the mods. now I know as well as everyone on this board that that is a load of horse dookie. So they tell me to convert it back to stock and see what happens. So I play along, but I have a lil ace in the hole. I convert the lid and filter back to stock, I block off the ram air, and then I auto-tap the car to get some readings from it. well I got the exact same readings as the dealer did even after I converted everything abck to stock, I was getting lots of knock retard at high RPM's, car wouldnt shift out of first at full throttle, and cylinder 3 would misfire. And so I bring it back to the dealer and they tell me its because the cat is clogged! the car only has 30K miles on it and the air/fuel ratio is 14.7 to 1.

Now here is my question. How can a misfire in a specific cylinder, a high knock retard at high rmp's, and the car not shifting at open throttle be caused by a clogged cat? any info on this topic is much appreciated

[Bass482]

The exact same thing happend to me...all of the same symptoms. I brought the car to the dealer and they replaced the cat under warrenty...

They tried to tell me that the exhaust had too little back preasure...but I said they were wrong and they did more testing and finaly said that I was right...

When you stomp on it, that increases the CFM flowing through the cat drastically.

It might backfire because the air isn't escaping out of the exhaust valves fast enough because its backed up all the way to the cat. The fuel and fresh air are forced into the cylinder and because there is still exhaust in there the gases fill up the cylinder quicker and it ignites before the piston is fully compressed causing a misfire?

Once I got my new cat everything was fine...so I decided not to think about it again... ;)

[Bass482]

oh yeah...

this happend to my car at 17000 miles [img]graemlins/thumbsdown.gif[/img]

[camarokidd10]

dude, thank you so much! the dealer says they arent going to replace it under warranty because theyre stating that my mods caused this to happen. so you know how much theyre charging me? $1100!!! you think I should just say screw it and go for the hi-flo cat?

[knowledgefreak]

can you say no brainer? and i would tell them you are going to report them to the bbb for wanting to charge you 1100 dollars for a factory replacement that malfunctioned. They have to prove your mods cause the problem.

Go get a 60 dollar catco or 160 carsound cat

[bu-bye]

<blockquote>quote:</font><hr>Originally posted by knowledgefreak:
can you say no brainer? and i would tell them you are going to report them to the bbb for wanting to charge you 1100 dollars for a factory replacement that malfunctioned. They have to prove your mods cause the problem.

Go get a 60 dollar catco or 160 carsound cat<hr></blockquote>

yea do just that. In no way do your mods harm the CAT. I would kick and screem till they replace it. Call GM if you have to. When someone goes all the way to the top they don't have time to b!tch and fight over a $25 or (less) part.

[Blac Drop Top]

They are so full of crap. Tell them to eat rotten cheese.

either call gm divison directly or buy a highflow cat.

[whtefbrd96]

No MAKE THEM REPLACE it the HAVE TO. And then after they replace it go buy a high flow cat just for spite !! :D

[Bass482]

be persistant and make them do it!!!! they have to prove to you that it's your mods.... If they try to pull the air/fuel crap again, tell them that you know the computer learns that the extra air is there and compensates for it...


Good luck! [img]smile.gif[/img]

[chevcamaro18]

yeah gm warranty is bs no matter what you will do they will try to get out of it so you are kinda screwed. sorry man but id go with the hi flow cat and shop around muffler shops for the cheapest install price better than fighting with the dealer

[camarokidd10]

I'm gonna call GM today and speak to a representative. I'm also having a meeting with the shop foreman tomorrow to discuss the issue at hand. I'm gonna be stern, yet calm and cool at the same time :D I've already ordered a random tech 2.5in cat from thunder racing, but I'm not letting the dealership get away with this!! I'm doing what Whtefbrd96 told me to do lol I'm gonna make then put a new cat on, then I'm gonna put the new hi-flo cat on just in spite of them LOL aint I a biznitch? MUAHAHAHAHA. but I will make them eat the price of this cat, aint no WAY that thing costs 1100 bucks. If I have to go all the way up the friggin ladder to the president of GM I will cause this is [img]graemlins/bs.gif[/img]

[Seppo Kaitainen]

You could try another dealer.

I clogged a HF cat. By the time I finally got around to taking it off it was "dolphin safe". At that point there was no reason to replace it.

[camarokidd10]

FOLLOW UP.....

whats up guys. well, the dealer isnt budging on this. So what I basically did was gave them the international sign for F U and took it to my friend's shop. we gutted the cat and took everything out of it, totally hollowed it out. And wouldnt you know it, it fixed my problem! no more misfiring, no more knock retard, and that biznitch gets goin like WHOA! lol so now that I finally got this out of the way, I added my intake lid and K&n filter back in and unblocked my ram air kit and she's running very sweet now. :D I just wanted to say thanks to all you guys that posted on this topic to help me resolve this... LONG LIVE THE F-BODY!!! PeAcE Ya'll, I'm out. [img]graemlins/fluffy.gif[/img] fluffy likes it too!