355 Catalytic Converters

Don't discount the fact that from mid 1998 through 1999, Ferrari used metal catalysts that are very durable. The earlier oem ceramic ones (1995 to early 1998) had a problem with the cores not durably secured to the housing and eventually worked loose and crumbled apart. The only cats I had good luck passing emission tests and avoiding CE lights was with oem whether ceramic or metallic.

I tried using MillerCat to rebuild one of my bad ceramic ones with a claimed high performance metal catalyst core, and it started showing "low catalyst efficiency" codes after about 8 months of use. I sent it back, they recored it again and it failed 6 months later. A spacer on the post catalyst O2 sensor kept the CE light off...but ultimately I found a set of the oem factory ceramic ones.

 

FYI: Ive got a set of high flow 200CEL cats for sale off my '99 spider... They were put in about 2000miles ago, and come with both pre and post O2 sensors (sensors may need to be replaced)...

PM me if anyone is interested!

 

Meant to say I found a set of OEM metallic core catalysts. One and done.

 

those would work on a 97 spider I assume?

 

I just called Glenn [Nuvolari]. He responded to an email in 15 mins and sent a pic! $1200.00USD.
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I bought Nouvalari cats for my 95B recently and there’s a ferment issue and bung for O2 sensor in wrong place on drivers side. It’s now week 2-3 with no solution from them. They asked me to send that side back to the UK to fix it, but then the car will be out of commission until they ship it back AND my car will be stuck on a lift at the shop that did the work. I bought these because I saw such great reviews and now I’m wishing I hadn’t. Hopefully you have better luck.

 

No problem on my '95.

 

Nouvalari ended up having an additional call with the tech that did the install to get more details on the fitment issues. They are going to make a replacement and send it out. Progress for sure.

 

If anyone needs original cats (need to have them re-cored); I have a pair from my '97 355. PM me and I'll send pics and will be open to reasonable offer. I purchased replacements I found on-line 2 yrs ago when I had my major done by Classic Coach (NJ) over a year ago.

 

you are almost ALWAYS better off with a quality aftermarket cat for our 355s and 348s. Stock units used ceramic cores and they weight a ton. I have ones made by gothspeed, one of the Stooges and they are great. He can make them to suit your ear if you are looking for a specific tone. Mine have a low rpm thrum like a Corvette and an F1 wail at higher rpms. No commercial version does this. But that's just my taste. The aftermarket is better. Check with suppliers because thy may be holding on to some lightly used Fabspeed or Tubi items. The aftermarket units flow better and are much lighter.

 

The problem is most of the aftermarket will throw codes if your car is a 1996 and on with OBDII and a post catalyst O2 monitor. The Bosch motronic is very sensitive to the calibration of the catalyst and will throw "low catalyst efficiency" codes. I had no luck and had to go back to OEM. I suspect your car is pre 1996 without the additional O2 monitor?

One work around is an O2 spacer or other trick, but then the O2 sensor can no longer do its job to ensure the catalyst is functioning properly.
For OBDII 355s (1996 to 1999) the best solution is to find a set of the OEM metallic core catalysts that became standard from late 1998 to the end of production in 1999. Ferrari still makes them, but they are crazy expensive. You can get lucky like I did and found some new ones for sale on eBay for a great price.

 

It is definitely possible to make an aftermarket, high-flow cat that will not throw codes for catalyst efficiency.

The way to do it is with a large diameter metallic core that has really high "precious metals loading". But since the price of the precious metals used in cats has doubled or tripled in the past few years, these are NOT going to be cheap.

And practically speaking, it's also not possible to get them CARB approved, and with so many states requiring this approval now, commercially it's just a non-starter.

 

Vince got a 348 so cat efficiency is not an error he would see.

As for the 355, the o2 sensor extender is not recommended for the front sensors, only the rear sensors in order to reduce the Cat Inefficiency code. The front O2 sensors work just fine as they have.

 

Nouvalari cats work just fine on my 98 with no CEL’s, for what it’s worth

 

Just a reminder that Fabspeed, Nouvalari or any after market catalytic convertors are not DOT/EPA approved. As a result, while they will pass an emissions test and not trigger a CEL.....they will flunk a visual inspection if your State requires one as part of the emissions test.

The EPA in recent years has cracked down on companies that make/sell aftermarket catalytic convertors so that they have to list the parts as "off road use only".

Fortunately......most of the 355 fleet has moved into the Antique classification for most States which exempts them from Emission requirements.