I just noticed something on re-reading this post- if a hyperflow cat for example has a port for the post-cat O2 would this still be fine vs trying a cat that doesn't have the port, or trying to remove/use extenders? For some reason when I first read this I took it to mean a high flow cat may not clean the air as well or otherwise cause mis-readings that would affect the fuel metering, but on re-reading I notice you specifiy use of extenders/removing/simulators... It seems to me that hyperflow has been a "trusted brand" for Ferraris in general, and I'm thinking I want to put them on mostly for the enhanced sound when the bypass valve is not sending the exhaust through the secondary system (and as a side benefit, if there is any lower heat generated). I'm not really looking for or expecting any performance increase given the valid point that the main cats aren't used when pushing the motor at higher RPMs/throttle use, but of course I don't want to damage the motor with incorrect fuel mix or throw any CELs. I liked the hyperflow/tubi combo in my 360, and I already have the tubi on my 355...just want that little bit more/enhanced sound at the lower rpms and I think the hyperflow will be the ticket?
Andrew I have a tubi exhaust and hyperflows on my car. You're welcome to come and see it/listen to it as I see youre in NJ. I don't get CELs and I don't use extenders. So far... One year and about 3000 miles.
Andrew I did not mention any "BRAND" of catalytic converter as my point was to explain how the 355 dual exhaust system works and that "high flow" cats are not needed and may in fact cause issues. The 360 does not have the same type exhaust system as the 355 and the 360 uses a completely different engine management system software. I am very knowledgeable of the software architecture of the 5.2 Motronic(USA Version) and some of the things stated by others here on this forum go directly against the software logic that comes pre-programmed into the ECM. When things are stated that go directly against the software logic it is indicative of a serious problem.i.e. the one making the statement doesn't have a clue of what they are talking about....this is very common problem on just about all forums. I will quote myself again; "An interesting point to be noted is that some people have installed the same high flow after market cat.......some get a CEL immediately, others get a CEL miles later...and some get no CEL's.......all of this is totally dependent on fuel metering efficiency, combustion efficiency, and overall mechanical condition of each individual engine on which these cats are installed. Might as well include the wiring harness,sensors,etc. At least you can see the many many variables involved." The 5.2 Motronic is designed to have a "pre" and "post" cat Lamba Sensor, therefore you never use a cat that has only a "pre" cat Lamba Sensor bung. The only comment I made regarding using O2 Sensor extenders is: "how that effects the engine when you remove it from the exhaust stream with extenders or remove and use a simulator I will leave it up to you to determine." It is up to you to determine the use or non-use of these type of products. drbob101 has sent you an invite....go over and check his system out and see if that is the sound you want....if so then you can replicate his set-up and I know he will help you out if you get any CEL's.
I have a Tubi, Hyperflows and OEM headers. I get P0433 and P0432 fairly regularly. I have the short extenders, but may try the L-shaped ones. Sound is perfect IMO.
Well Bruce, I was hoping there could be a clairification that it should be OK with the dual port/bung hyperflows (as opposed to not likely being OK to use extenders or otherwise trying to trick the computer), but it seems you made it clear that it's simply not ideal either way given the potential issues with the 5.2 system. Kevin's post on codes just confirms potential issues- thanks for posting Kevin as that would be the idential set up I would have preferred... And thanks for the offer Bob- it's tempting to have a listen, but that may be torture if I don't then put them on my car I'll drive the car for this season and see how I feel when the car is in for service next spring...why did they have to make it so complicated!
I didnt replace the OEM cats with the hyperflows electively. One of the OEMs was rattling. I do have new OEM headers also, just to clarify.
Kind of my issue- my mechanic said OEM cats still looks OK, not throwing CEL etc but one may be just starting to deterioriate- and I hear rattles when the motor is cold- not sure if cats or bypass valve. I don't notice the rattles as much when the motor is warm. I too have OEM headers- you have the same set up I would like with hyperflows combined w/OEM headers and tubi exhaust. 21,000 miles on the car (1997). This thread was very helpful to me- I will wait to make the decision... The OEM's are the safest bet but more money- can "gamble" and put hyperflows on and hope no CELs but realize they may come and at least very informed of that risk given this thread. Of the aftermarket, hyperflows seem to be the ones recommended by my mechanic and by several other people here on f-chat. And they do show a 355 in their Forza advertisements
Exactly how mine sounded at 21k. Rattle cokd, went say. I have a lift so it was obvious where it was coming from when on it. I thought something clutch related. Call Troy at hyperflow also. Very knowledgeable and hdloful.
Can I ask you a really dumb question? Actually it's a smart question directed at a dumb comment. Did I say anything about test pipes? You do not have an understanding of what the oxygen sensors are doing or about this matter in general. Even someone with absolutely no mechanical knowledge whatsoever knows that test pipes will throw on a Check Engine light in a 5.2 car. That's because 5.2 cars have an extra set of oxygen sensors. Thanks for attempting to teach me something I've known about 10 times as long as the length of time you've known about F-Chat.
To the original poster - I would like to help answer your question so you can rest assured. There are many threads on this topic in the archives which I can possibly dig up. But from my own tangible years of experience specifically with 2.7 and 5.2 355 cars... **THESE STATEMENTS ARE FACT, NOT CONJECTURE** If: 1) Your engine is running healthfully - the way it should, and is under the proper care of a qualified mechanic; 2) You have aftermarket catalytic converters installed correctly that are from well-known companies who are producing catalytic converters that do the job of reducing emissions correctly; 3) If your oxygen sensors are not defective 4) You had no other issues before fitting the catalytic converters; 5) You have an aftermarket exhaust installed correctly; **No Check Engine light that you may see in the future is being caused by the existence of the aftermarket catalysts themselves in combination with an aftermarket exhaust. If you have a code that corresponds to the catalysts, then the catalysts may be defective. Otherwise, there is something **else** going on with your engine. Plain and simple. 2.7 or 5.2
Sorry, but your statements above are collectively a THEORY--not fact. Hyperflow, for example advertises that their cats flow somewhere very close to test pipes (4-5% I believe). This is a material deviation from the OEM parameters programmed in the sensitive Bosch 5.2 ECU. Clearly this change alone throws off the ECU because the voltage generated by the downstream O2 sensors falls outside the OEM range. Once you've driven enough drive cycles in closed loop mode...bingo...catalyst inefficiency codes. By the way the PO owner of my car had Hyperflows installed at the recommendation of an authorized dealer. I just had my major done a couple of months ago and a well known shop confirmed the car runs great.
Kevin- what do you do when codes come- just reset and then the CEL is off for a while again? Interesting that the dealer recommended the hyperflows on your car. I'm going to call a couple of local dealers and then hyperflow to get more info from them- unless there is some sort of a special deal on OEM, I'll likely go hyperflow. While there are some different opinions on this thread, this has been quite useful information for me to understand the 355 system better and the pluses and minuses of various options w/cats. A couple of very informative posts in here....
How then do you explain the fact that plenty of owners of 5.2 cars have Hyperflows (or similar) and have NEVER had a CEL? My car runs beautifully with stock headers, Hyperflows cats, and a Nouvalari exhaust (a setup which has been on my car for 8000+ miles now). Several other owners have reported the same. I tend to agree with the thrust of 348SStb's statement.
Yes, I simply check the codes and reset. A Bluetooth OBDII scantool like the ELM 327 paired with a smartphone makes this quick and easy.
I have never claimed to have the answer to this...variations in the sensitivity of the ECU's perhaps. My car is a 1999 so I suppose it is possible for later cars to be more sensitive as a result of increased environmental regulations. Just a theory. 😃
Fair enough. Mine is a '98. Unlikely there'd be much difference between the two just because of the year. I've asked this question before but no-one answered: Is it possible that the U.S. cars are set up to be "more sensitive" than the Euro cars? The reason I agree with the thrust of 348SStb's statement is because he makes the point very clearly that if you are getting constant CELs it is likely NOT just because of the addition of aftermarket cats.
I spoke to Hyperflow- often the CELs upon changing cats are casued by connectors that can go bad...seems they are not made well and/or are aged and when "disturbed" to unplug and replug into new cats that can often lead to a bad connection- the issue is often the plugs/electrical vs. the cats themselves in other words. Removing cars that have CELs before the cat switch that are caused by something other than the cats, that makes sense to me as a potential reason that some cars get CELs and others don't after various aftermaket cats are installed. After all this, I will most likley upgrade to hyperflow- the only question is timing. I'll drive the car more and may simply budget in upgrading to them with next spring's service, unless something else brings me to the shop sooner (hopefully not though!)
I suppose that is plausible. US EPA and whatnot... Well we can agree to disagree. Oxygen is just a proxy for unburned hydrocarbons and an O2 sensor approximates unburned hydrocarbons for emissions purposes by measuring voltage of gases that pass over it (once heated to the proper tempurature and closed-loop mode is entered). To say that the gases passing through higher-flow cats will not materially deviate from more restrictive OEM cats (because of less restrictive cores, larger cells, etc.)--and therefore will not register significantly different voltages than the 5.2 ECU is programmed to accept with OEM cats--is somewhat naive.
Rechecked this connection at the cat, it looks pretty tight and solid. Better pic attached Image Unavailable, Please Login
Another item of interest drove 140 miles after the L shaped spacers were installed before the CEL. Reset Drove 122 miles CEL again. Reset Drove 93 miles CEL again. Reset Have gone 119 miles this time and it is still NO CEL, but next drive it could come on at any moment. So thinking it is NOT in the wiring ?
Are your o2 sensors original? I'm surprised at how many cars at or approaching 20 years old still are. IMO they should be replaced during every engine out maintenance. (or now if they are old)
The connectors may look tight externally, but what is the condition of the actual contact points? Those are what hyperflow was describing to be as getting brittle with age in many cases...
