F355 Cat question?

You probably should look into why it melted (excess unburned fuel in the header) as well as why the TCU did not throw a slow down light. It is likely that this is the tip of the iceberg.

 

I had the same problem except on the right side. My right was completely gone. Nothing more than a straight pipe before it set off any lights. Presently having my OME cats recored by Fabspeed. This should give me the OME look with improved performance. In California we are required to have an approved cat to pass emissions. My cats will have the original ASNA number on the outside so visually should pass. Ill have them tested once I get them back on the car.

 

is there a way to check for excess unburned fuel on one side?

 

Use a pyrometer on it. The cheapest place is Harbor Freight. About $25 on sale. You can check for excessive heat on the cat - basically anything over 350 degrees as I remember. Use the other cat as an index. Make sure you measure on the exact same place of both cats. Then for fun, test your headers near their exhaust ports and then the header covers at the bulges. Hot spots may indicate cracked pipes. Then you can take a break and chase your pet kitties with it.

 

meany!

 

Waiting for the new CATS and I'll check them.

 

Are those OEM cats?

 

Yes, definitely not. I suspected as much as they appear to be metallic core where as OEM are ceramic. I have heard that the new Ferrari cats are metallic core which is why I asked.

You might consider having someone check the exhaust gas composition before the cats. You would need to find a shop with a gas analyzer. It does seem very strange that they would melt down w/o a SD light and the O2 sensor looks like it could be shot as well, but I believe you said no CEL either.

Those cats also look rusty which might mean they are cheap after market units which could be the reason that one failed. Just guessing on that issue though.

 

Saw a 1999 F355 this past weekend with what appear to be original cats. Cores were metallic. Late change?
My '97 were ceramic.

 

I don't want to scare you...but you definitely need to look into why that side is getting so hot. I'll share a local friend's bad 355 experience...bought a 355 with no PPI, the seller 'graciously' replaced both cats after he complained they overheated right after purchase. Fast forward a year...he brought it in to look deeper into the problem, needed major engine overhaul (apologize, he didn't say exactly what) and instead dumped for a $25k loss and bought a reliable 'Vette to enjoy....

 

Concerned about that myself. Car has run fine but right cat was completely blown out while left was still intact. 25,000 miles on the car. Have new metallic cats coming. Just bought a cheap laser thermometer from HF. How hot should a well performing cat be on the pre and post ends? What temp should be coming out of the stock headers? Thermometer goes up to about 999F.

 

A cat operate best at around 1000*F.


I would not worry too much about you car. You probably had ceramic cats which break up and blow out the exhaust. You said you have a whitest power on you O2 sensor. That is characteristic of a ceramic cat breaking up.

Very unusual to see a metallic cat melt. Defiantly something amiss with the OP's car. But could be just cheap cats.

 

yes

 

My '98 had cats replaced in '02 with OEM. They were ceramic. In 2012 when I did a major the core on the left cat was loose but still there. I replaced them with Fabspeed.

 

Sent you a PM

 

Hyperflow, Fabspeed, Nouvalari are all pretty much the same from what I've seen.

 

The tubing itself (pre cats) should read around 375°F for a 348 to 400°F for a 355 ....... +/- 30°F ............. ideally they should be the same temp on both banks or within 25°F from each other max.

 

Thanks

 

I had 44K miles on my 95 355 with the original cats before I sold it. Cats weren't in bad shape either. Old but surprisingly not bad. If I were you I would use this as an excuse to get a set of 200-300 cel cats