Guys, the following is plain and simple... Aftermarket catalysts, headers, or any combination do *not* throw on Check Engine lights, whether in 2.7 or 5.2 Motronic. The engine has to be running healthy to begin with in order to have no Check Engine lights. Any competent and experienced mechanic can test the exhaust gases to see if engine is sick or healthy. A new catalytic converter simply doesn't solve the problem of the existence of a a sick engine sending the wrong exhaust gases through the system. This he would do by testing the gases before the catalysts, with the oxygen sensors disconnected. Then he would test them after the catalysts.
WRONG...if that was so why is it you take a perfectly running 5.2 car and put test pipes on it a cel light pops up? Why are O2 extensions used in the farthest back spot in a cat? that statement is not true...dont believe me if your car is running right and healthy go put test pipes on and see what happens
Reading and taking notes, I currently have the L shaped extenders of it. This is a pic of under the car passenger side kind of an awkward angle. Almost tempted to call or stop by the dealer to at least talk to them. They may zip their lips when emission alterations are discussed lol. These L extenders are about 2" by 2" Image Unavailable, Please Login
High flow cats "shouldn't" cause a check engine light, but its also important to note that not all high flow cats are NOT created equal. For Example: Fabspeed manufactures a set of high flow sport cats for all F355 cars (both 2.7 and 5.2). In our fabrication process, we utilize a 200 Cell HJS Tri Metalic catalytic converter core. HJS manufactures an extremely high quality catalytic converter that flows at a high volume rate but still filters emissions effectively enough to keep your ECU happy and the CEL off.
I have a 5.2 three years with straight tubes, no extenders and never cels. I put on no orginal cats, plug and play and no cells either. Change the type of catalyst, it is no reason to bring up the light.
it's impossible you have a 5.2 car with straight pipes and no CELs. is your CEL bulb even in the dash? you should see come on and then go off when you start car.
+2. Every 5.2 F355 owner I know (including myself) that has installed aftermarket catalysts on their perfectly running car, started getting "low catalyst efficiency" codes within a few days to a few months after. My local dealer says that the Motronic is simply very sensitive to catalyst monitoring and is looking for a very narrow band of parameters. If they fall outside that, it throws the dreaded CE light for low catalyst efficiency. Usually, but not always, a O2 "extender" either short, long or L shaped can eliminate the CE code/light. But by removing the O2 sensor from the exhaust stream you are eliminating the monitoring function, and if there is any feedback from the secondary O2 sensor to the Motronic (there is some debate on that) this is also eliminated. Only the factory catalysts are guaranteed not to throw CE lights...anything else is a crap shoot. I returned by car back to oem catalysts.
This is essentially the same set up I have with tubi exhaust. No CEL. Maybe it's the headers? 😉
+1. I have stock headers, Hyperflow cats, and Capristo (Level 2) exhaust on my 5.2 ('99 F1 B). Have never had a single CEL (since 2007).
.....interesting thread. I just bought some Evoflow cats. I have been getting Low cat efficiency codes on my 25k mile OE cats. I have TUbi headers and exhaust. We shall see!
Curious what CEL codes ( P number ) you have experienced. Check post # 9 &18 and you can see the different ones I have gotten. Also curious one side or both sides, guess the number error codes would tell me that lol
Wow such a wide spread of results. Guess with 3 major components to the exhaust system, headers, cats and exhaust and then add the numerous brands of aftermarket parts and I have total chaos Still strange that I drove for 3000 plus miles and nothing, then L and R side codes ..... Then add the spacers and then having both new codes come up on Bank 1 the driver's side totally confuses me. Strange that nothing pops up now for the Bank 2/passenger side ?
as mentoined above..stock headers seem to be playing a role, to not trigger CEl with high flow cats on.. what are the usual high flow cats for the 355, these are some that come to mind. Nouvalari Fabspeed Hyperflow EvoFlow Larini any others..? I dont mean every brand.. more the brands that are used the most often. it does seem many are running Hyperflows..?
It could certainly contribute. More heat contained in the exhaust (stock headers are best case here) will light off the cats faster. And as mentioned, the quality of the cores as well.
$1200 for set of Nouvalari cats is what I'm willing to spend. $2500+ seems to be the range for the others. Larini's are $3000+. but if I got set of Nouvalari and after x time I started to get cels I would lose my mind. this is why I'm quiet perplexed as I thought for sure hf cats were plug n play and done. something is definitely going on with the cores from one cat to another to trigger or not a cel.
Heres an interesting read on the topic. Http://www.randomtechnology.com/technical.html 1994 ferrari 348 spider , third owner purchased may 2013 w/ 27804 miles
talk with some people who have the Nouvalari cats and get some feedback...its better to spend a little more up front then to do it all over again in a year..
Of course, I`ve bulb, light when the key is on and becomes off when the motor run. If you want, can make a picture to straight pipes-out of the car- and cel light. I put cats again to pass the emissions test in Spain. I too find it curious, but....
It's strange...I had a problem with my 2000 360 whereby a "pre-cat" in the header let go and went downstream, taking out one OEM cat. My mechanic recommended hyperflows as two of them (left and right) would be cheaper than an OEM cat and were better made to boot. I took his advice and we put in the hyperflows- the car sounded great with them, and never a CEL. Now I have a 1997 355 spider, and while installing my tubi my mechanic said he noticed one of the OEM cats looked a little tired- no running issues or CELs but just made note. So I was planning on doing an upgrade to hyperflows with next year's service since I was so happy with them on my 360...if anything, all else equal, I figured the 355 system would be less "sophisiticated" than the 360 system, and now I'm reading some of you are getting CELs with the high flow cats on a 355. I'm a little surprised... I'll likely still do the hyperflows next year since my mechanic likes them- I don't think he has issues with them otherwise he wouldn't be recommending them. He said we can wait as my OEM cats may be fine for a long awhile, but if I have the extra money in the car budget next year I'd like to upgrade to the hyperflows proactivley
