F355 with no cats..

Actually, tampering or removing emission control devices is a Federal offense subject to monetary fines and/or imprisonment. What individual states do with regards to emission testing/inspection has nothing to do with the overriding Federal laws.

 

Exactly true, that is why none of us would ever do such a thing.

 

to my understanding, the post o2 sensors are for cat efficiency.
meaning if the cats are not scrubbing the exhaust gas well enough, the cel is triggered as a warning to check/address the issue.

now with test pipes or even high flows it has been discussed already at length that cel are still possible even with spacers

questions is, other then putting up with the light, is the ecu adjusting any parameters how the engine runs while the light is on? meaning no harm?

or could the ecu be adjusting A/f ratio? meaning potential harm if left.

but I think it is the pre-o2 sensors job to do that?

all this to say as im seriously considering running test pipes on my 5.2 car, with best efforts to lessen or solve cel with spacerrs, that if I'm unlucky and still get cel is it ok to just ignore the cel, if indeed related solely to post o2 sensors.

Id hate to see a constant cel, but I have to anticipate it may very well be reality to enjoy the incredible sound!

 

The secondary O2 has basically no control over engine management. Number one input is the MAF then small corrections of the first O2 for engine control. A/F ratios.

 

ok sounds good thanks..

would suck to see a constant CEL.. with test pipes.. if spacers don't work..100%
but good to know.. as long as the CEL is related only to post 02 sensor cat efficiency, then its pretty much safe to ignore and leave it..

 

No it's not safe to ignore and leave a CEL...because you will never know if you have a new code come up thats not related to your test pipe's if you just leave it.

 

I ran straight pipes with a 5.2 and Larini for about 5 years or so. Everyone would marvel at the sound at WOT, at cruising speeds the drone was very loud, It really smelled of exhaust both in the car and especially behind me. I used to drive a lot with large groups of Ferrari owners and some would tell me that they did not like driving behind me because of the smell and my car would even give them headaches. The check engine light was always on, and I even used to put a piece of black electrical tape above he light display cuz the check engine light would bother me. I have been running the stock cats back on the car for the last couple of years, no more check engine light and car is not as loud obviously, but still sounds good...

 

great feedback from everyone.

regarding cel I wouldn't bluntly ignore it.
I will use the special mini cat spacers from Fabspeed.
and will have fingers crossed that I won't get any cel.
but if I do get cel I will check it to make sure it's post o2 sensor related and not something else. and delete it when possible. and then hope it's far in between.

my comment to ignore it was more in regards it's not affecting the engine in meantime as confirmed above until I can check/delete it periodically.

perhaps I'll pick up an obdII reader so I can deal with it at any time.

regarding the smell that will have to be confirmed myself.
I do expect it to smell more. but as others commented above some say it's not so bad and others felt it was bad enough.

my car as is sounds great with Fabspeed headers, stock cats and Nouvalari exhaust.
more beautiful sounding then anything while I'm on the road.

but after hearing my buddy's 355 with test pipes, I feel like I'm leaving a lot of the 355 experience on the table.

 

I have Tubi Manifolds, Tubi test pipes, and Big Daddies 02 min cat extenders on order.
My primary reason for these changes is to cut down on heat issues and manifold failure issues in the car

Other than sound, will these changes increase performance at all. HP gains, throttle response, etc ?

 

The test pipes should increase power on top end. It will be interesting to see how the Ecu responds and adjusts to the Big Daddies. Sound will be awesome.

However, if you sense a loss of low end or maybe even mid range torque from the test pipes, I'd order a pair of 200 cell HJS cats (about $400-500) each and have a shop weld them to your test pipes. This route is alot less expensive than buying pre-made fitted cats ($2500-3000), especially if you can find test pipes for $300 .


My car orginally came with gutted OEM cats, so I have no gauge of what the low end torque loss from oem/200 cell cats to test pipes is.

But ironically, I felt a gain in low end torque when I wired my bypass valve open. It could just be me, but I'm confident it didnt feel slower. Felt much more responsive. I have a 2.7 if that matters.

 

Ken,

Thanks for your response. What is the setup on Euro cars ? Wouldn't these be catless, like the test pipes I'm installing ? I would think the performance of my car once these items are installed would be similar to a Euro car as fas as performance.

 

My 98 F1 has 200 cel Evoflow CAT's ($1400) and no muffler. My 95 has test pipes and a Capristo. Sound is very different but I don't feel much difference in performance. Perhaps the 95 is a bit more punchy on low end?

 

Thanks Dave. Hope you're doing well.

 

I have a euro spec 5.2 355.

they are not catless.

exact same exhaust setup as all 5.2 cars.

except Euros don't have the third thermo coupler at the bypass and therefore no associated cat ecu.

so only 2 thermo couplers and 2 cat ecu's


after so much debate here. I may go a different root.

I may look to replace my Nouvalari exhaust with a TopSpeed challenge exhaust.
and just keep my stock cat setup.

which I'm thinking can be very close sounding as test pipes.

 

Thanks for the clarification on euro set up.

 

Well three weeks and hundreds of miles later, I must concede that I prefer the sound (mostly the tone) and driveability of the cats rather than the race pipes.

IMO, looking back, straight pipes were so loud it overpowered the rest of the driving experience.

 

This was my experience too. The tone is better with cats opposed to
test pipes. Sold my Tubi test pipes and haven't looked back.

 

An update on this thread with my recent experience.
Bought some angled O2 sensor extenders a couple of months ago (only like $30/pair on eBay, chromed nicely, look/function just like the *way* expensive Fabspeed ones).

Installed a few weeks ago with some coarse steel wool inserted in them.
I kept meaning to clear codes, but never thought to plug in my OBD reader when going out for drives... figured I'd get around to it soon. Lots of rain lately, so not much driving time.

Tonight, on a quick drive, I noticed the CEL had turned itself off. I know that OBD codes will clear themselves if they aren't experienced after like 3 drives of sufficient length. I'll check the actual codes tomorrow to ensure all is clear, but for now it looks like I can be chalked up as another successful story of angled extenders with straight pipes (no cats)

My Setup:
Rebuilt OEM headers in re-wrapped OEM heat shields
Cappy I (no 3rd bung, so the 3rd thermocouple is just tied off to the side, connected to the ECU)
Test pipes (aka no cats)
Angled O2 extenders with steel wool inserted
4 OEM O2 sensors and 3 OEM thermocouples, all functioning

Finally, no CEL after 3 years of swapping to OEM cats just long enough to pass inspection. Time to get this thing in for this year's pass while it's still clear.

 

Great research. I'll do a similar write up soon on the big daddies with a similar set up to your.