Ok i have a SS/SC. I had a stock downpipe but it was clogging. SO i went with a full 3" exhaust and put a Cobalt Addiction Downpipe on it. Of course i reset the computer afterwards for readings. But. Ever since then i have been getting on and off CEL's..
These are the codes:

PO300
Random/Multiple
Cylinder
Misfire Detected

PO420
Catalyst Efficency
Below Threshold.

Now i have been having a big metal clinging noise under my car where the Cat is but im thinking its the heat shield. But having a Catalyst CEL doesnt help that. I also dont feel as much power as i once did. I have recently changed my Plugs and check them to see if one is messed up. And theres nothing.

Any Ideas?

 

bump

 

Yous sure that cat is not clogged, That would give you those codes

 

The one code i believe is telling you maybe that the cat is plugged..? Any wierd smells,? Lost of power could meet cat, however there is a misfire so the sluggishness could be that, Seems more fuel related maybe?

 

the clunk noise is probably the inside of the cat coming apart. you have a p0420 so your cat is pretty well fucked. the lack of power you're feeling is also common with a clogged/melted cat.

the p0300 is a miss fire obviously. This could be caused by the cat being clogged and restricting the exhaust, and more than likely it is. if a coil or plug failed it would set a misfire code for the cylinder missing, p0301 through p0304. the last number in the code will be the corresponding cylinder, p0301 = cylinder 1, 302 = cylinder 2 ect.

So basically, your problem is more than likely a clogged cat.

 

First, how do you know the first downpipe was in fact clogged?

Second, assuming that was the problem, simply replacing the pipe doesn't fix the original problem. Now you just have two bad pipes. You have to address the problem before you replace the parts.

 

^very true. you need to figure out if you're dumping raw fuel into the cat or what because something is wrong with your engine and causing it to clog up.

also, what do you mean you reset the computer? how'd you do it?

 

how do you address the problem. have a bad cat replace it right? Something on my car is clogging it or just a bad cat. Its the Cobalt Addiction 3" and i have heard of problems. So what should i do... Check the cat and see if anything falls out? Its just recently started to start popping when it idles down in gear. Could that explain a little more?

I have 60lb injectors on a 2.9 with a Intense Bin File. So the tune may not be correct. I reset the computer by unpluggint the battery for a hour right?

So if its the cat.... what do i do? Buy another again or go cat less or get a tune checked out?

 

how long have you had the ca down pipe? you can check the cat by taking it off and seeing if anything comes out, it might, or might not. if it does you can see if cobalt addiction will refund your money or hook you up with a new cat. usually cats just go bad over time, i've never seen one go bad really quick..

 

ive had it on since about September. Im going to get the heat shield above the cat straightened out tomorrow and check the coils. If that doesnt stop the metal grinding. Then its the cat.

 

Well, that extra information helps. You are flooding the **** out of your engine, super rich. No pipe is going to fix that.

What injector size is that intense tune designed for? Did you actually tune for 60 pounders?

 

They said they did. Dumb question maybe. but running rich wont blow the motor will it? My exhaust constantly has black smoke coming out of it

I got a Heat Exchanger and a 2.8 waiting to be put on

 

Okay, you keep giving me more information that makes me certain. Black smoke means super rich. And yes, it can destroy your engine. Your misfires are a result of fouled out spark plugs. Your clogged cats are due to this as well. Sorry, but your new Downpipe is also now ruined.

You need to get a tune, fast. You need new spark plugs too, valve cleaning, and yes, another new downpipe.

 

So far i found out. I was misfiring on 1st and 3rd cylinder. Im changing plugs to Autolite 3922

 

You still haven't fixed the mixture problem. If you put in new plugs first before you correct the mixture, you'll just ruin those plugs too.

 

my next step is to try and fix the heat shield that i think is the problem. if i fix it and it stops the roaring. Then i know that was it. if it still roars. Its the CAT. and then ill take the cat off and check. yeah i need a new tune.

 

Well now its a bad rattle all the time. Sounds like its coming from the resonator from my CTI exhaust. Ill find out monday

 

Stop. Just stop. Your problem is your tune, plain and simple. Fix that. Quit chasing the symptoms and fix the cause.

 

^^^^ people just dont understand

 

Well come to find out. My resonator was a spiral resonator. The spiral weld came loose. Which caused it to be rattling. So is was a porr weld. THANKS