SDL and overheated cats/headers

This brings me back to my main complaint.... I have flow thru cats now just installed them. My car sounds like a$$ now, and smells like I'm dumping fuel out the exhaust even with O2 extensions..Switching to another sport cat and it wont sound any better.. I have a tubi on now...I have a nouvalari on the shelf. The tubi had a nice high pictched scream but was to quiet. Not sure about going through the labor to put on the nouvalari and have it still sound the same and not loud enough....I think it sounded good with stock cats but to quiet. Looking for the best sounding set up without spending a fortune

 

Randy,

The extenders have nothing to do with the smell - the smell is coming from the exhaust gases that are no longer processed by the CAT's since the elements are gone. The extenders are only used to fool the rear 02 Sensor (to make the ECU think the CAT's are working)

And, the CAT's have little to do with the sound compared to the muffler.

 

I understand cats dont have a lot to with sound.....But enough it lost that high pitch. Thats enough to make not like it.

 

Bottom line to all of this IMHO..

Don't drive the car, until you pull that cat out of it and look at both ends.
If it is broken, inspect the other side while your at it.
Get replacments cats, what ever you choose.
Start the car and monitor manifold temps at EACH cylinder with an infared temp gun and compare your numbers.
Do this as the car is warming up from cold.

This will give you an idea as to which cylinder(s) are causing your over heat issue. From there you can narrow it down.

You converters should not be glowing red hot..at all. That is a fire hazard. Be thankful you caught it in time.

Do not automaticly assume its a bad sensor or thermocouple. They could very well be doing there job as designed. Which in this case its appears they are.

If you have any questions, the fine folks here will help you out.

 

Now, that's good advice - thanks for posting.

 

Just another data point. Had a similar issue with an over-heating cat. In my case the problem was a bad #7 ignition wire. Key is to properly diagnose. Simple fix.

 

Ketel:

Go for the FabSpeed re-cores if you need new cats. California STAR requires approved equipment to pass smog and none of the aftermarkets are approved. (I know that you are aware of this but adding it before the out of state guys chime in with other products). The re-cores of the original cats pass the visual test and mine tested super clean on the smog. Added plus is that they are supposed to improve performance. I haven't noticed as my cats were completely blown out and hollow before. I believe that the cost will be in the $1,700 - $1,800 range. More if you want a ceramic coating but then they don't look original so it defeats the point. Push them for an FChat discount and you should end up at $1,700.

 

Good point though I would think if you had a misfire that bad on and OBD II car it would throw a code for it. That would be a P030x code where x = cylinder #.

 

I had oem cats and Tubi exhaust. My OEM cats started to rattle. I replaced them with Hyperflows.

The Cats definitely changed the sound. I have a spider mind you and my top is mostly down and I hear my exhaust note clearly. The lower rpm sound is richer and louder, no doubt.

I dont get the desire to have a loud car or lets say a louder car. My car sounds fantastic and is plenty loud enough. It shrieks in tunels and purrs otherwise.

I was on a group Ferrari ride with highway driving and on pulling into the destination parking there was a group of guys looking under my car to see what was up. The hyperflows are less than $2000 and will eliminate your fuel smell also.

My two cents.

 

Agreed. When I go my cat the cats were hollow. With a tubi it was loud and shrill. I put Nouvalari cats on for emissions thinking I would put the hollow OEM cars bak on after. BUt I preferred the sound with the Nouvalari s on. Mellower at lower RPM and loud, but not a shrill up top. Nouvalaris were $1170 at my door and internally 200 cell metallic core, high flow.

 

High flow cat's will make the car a little louder. At idle, my car had a deeper tone as well. I agree with Bob and John, that changing the cat's will alter the sound. If the re-cored Fabspeed cat's were available at the time when I purchased mine, I might have gone in that direction to maintain the OEM look. Sounds like Peter has had good luck with these. CA inspection requirements are a lot tougher than MA.

 

You have to gut the bypass pipe cats to get the high pitch back. What's happening is your primary exhaust path now has lower restriction than the bypass so the exhaust doesn't go through the bypass losing the higher pitch.

 

Pete
I think if you do that on a 5.2 you will get a CEL

 

How? That flow path is not monitored by an O2 sensor
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Just buy hyper flows or something similar end of problem for life! I believe. Make sure they r ok for your state.
I am not taking sides here but I do wish everyone would post actual experience as opposed to speaking like its a fact when it's not. It would be nice knowing weather I am sometimes getting an opinion or a fact. Over the last many years sometimes I have been given advice that was presented as fact and yet it was just an opinion and sometimes even worse it was an opinion of someone who didn't even have a car but was presented as if they had first hand professional knowledge of such a problem.

Ps. Just remember i appreciate all you guys and your help over the years and I am just trying to pay it forword.

 

Try it and see.It has something to do with T thermocouple for exhaust by pass valve.

 

I don't think so because my capristo has no secondary cats and the thermocouple plugs into the bypass. I do get check engine lights but only rarely, maybe every 5000 miles or two years. I do have the minicat between the o2 sensors and the hyper flows though.

 

So, I pulled the Bank 2 cat today and here is what it looks like. I had another Fcar buddy look at it and he confirmed that it was toast (no pun intended.)

So, I am in the market for new cats. As TrojanFan said, I am a CA resident so more rings to jump through with our local friendly DMV than most of you folks. I'm leaning toward Fabspeed re-cores. I already have an aftermarket XOST Maranello exhaust which, for reasons that escape me, does not have a bung for a thermocouple. As such, the Bank 1 thermocouple is tied off to one side. I either have to get a bung surgically added (i.e. welded) into the exhaust or trade it out completely for another system (i.e. Tubi) that already has a bung.

I'm ok with the current exhaust but not a huge fan. It's a little loud for me, to be honest. I have a spider. The sound is tolerable but when I have passengers they complain its loud and we have trouble carrying on a normal conversation. I have heard there exists an aftermarket kit that can quiet the exhaust note via a dash switch. Send me a link if you know one out there.

On the more important stuff, I'd like to hear opinions from those, especially in CA, that have experience with swapping out their OEM cats and STILL MEETING SMOG requirements. That's critical. Fabspeed re-cores can do that. Not sure about Nouvolari and the others so send me feedback and suggestions.

Thanks all.

ketel
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Yeah its toast

Need to find why it got toasted
Aftermarket cats work fine I have them, Just make sure they are 200 cell and made of metal

I tried OEM cats vs aftermarket and only saw a 10ppm difference in HC, evo cats I think from Irvine CA

http://www.ebay.com/usr/prospecusa?_trksid=p2047675.l2559

Call hom on the phone tell him your from Fchat
http://www.evoflow.com/

 

Agreed! If you put a new cat in you might just bandaid the problem until the next meltdown. At Stoogapolluza Mitchel (YELCAB) and I were discussing your car and latest cat/sdl issue. We are in agreement. If this was a new car to me I would assume neglect. I would start ownership with a fresh major service that included fuel injector cleaning and balancing and proper cam timing. More than part replacing would be needed to be done for proper sorting like fuel pressure testing, compression and leak for example. The 355 is more in need of exact cam timing as the beginning of proper physical conditions that make proper mixture control possible. Physical systems need to be checked like header integrity to prove the possibility of proper running. With motor out while you are in there is a great time to examine engine wiring harness for proper connections and harness integrity. With engine out you can see things that you might miss with engine in. Things as simple as a cracked senor connection can have you pulling your hair out and chasing your tail.

OTOH, You could "just" go after the codes and things will work for a while until the next issue. Often problems compound with multiple weak points and the most stressed finally fails. So you fix that and the next weak link takes the system out. Rinse and repeat.

 

Ketel, I hate to say it but I think you need to take your car to a good mechanic and let them fix it for you before you do any more damage. I don't believe you can fully sort this car at Stoogefest or on your own via Fchat. This is said with the best intentions.

 

In your pictures I can see straight through that cat. The burnt cat is a symptom, not the cause. You are getting a lot, and I mean a lot, of un-burnt fuel in the exhaust from bank 2. You have a serious problem. Possible suspects are fuel delivery, burnt exhaust valves, a melted/cracked header leading to serious air entrainment into the bank 2 exhaust, very bad misfires (can not see how you would not notice this or have a code(s) for it), bad O2 sensor.

Being a 5.2 car and the observation that this is only a bank 2 problem (for now) I would start by pulling the bank 2 plugs and seeing if anything looks funny. You should be able to tell if there is a serious misfire or a cylinder running extremely rich by reading the plugs. Then check the bank 2 header for leaks. With a glowing red exhaust you may find it is toast too, but again, not necessarily the cause, though it could be. Have a compression check and/or leak down done. If you find low compression/high leakage you most likely have burnt exhaust valves. Lastly have the injectors checked, particularly on bank 2, for leakage and proper spray pattern and flow rate.

Anyway you look at it I think you are in for big bucks: at least cats, probably headers, and what ever engine work you may need. The car needs professional help. I agree with FBB here, deferred maintenance. You have had problems with the car since day 1 and too much DIY not addressing the real causes.

 

Agreed, also with the best intentions. Once you get the car back to a proper baseline, ongoing service will be much easier for you to handle.

 

What happens if the by pass valve fails do you get the same overheat situation of the cats and also the slow down light coming on. I had this coming back from Silverstone last week, everything was ok cruising at 3000 rpm through roadworks then when I started to up the revs to 4200 the sd light started to flicker on and off so slowed down. And then later got up to 5000 rpm and the sd light came on and car went into limp mode for half a mile. I slowed down again and the light went off and car back to full power. There is a rattle on tick over and it thought it was the valve but maybe it is one of the cats but it has just gone through a MOT and all ok but not sure which set of exhaust pipes he put the probe in. Going to strip the exhaust down over the winter because I think one of the manifolds is blowing !

 

Just another observation from the photos:

If you don't have metallic core CAT's (I doubt you do), then it appears you have some metal slag that has been burnt and caught in the CAT. I'd guess that's metal from your headers. I'd bet your header(s) is done.