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Yes. It works. You don't need any minicat on sensors. Primary O2 sensors are BEFORE cats.
I went with 100 cell IIRC.
Thanks for replying.
Im talking about installing minincats on the post catalytic sencors.
Those are the once that throw CEL errors if your cats are bad or in this case missing.
Else if a tuner disables the sensors in the tune to keep the cell light away the car wont pass emissions test.
I'm wondering about the overall setup. If it would be beneficial to driveability and performance.
P.S.
I just realised my phone auto corrected cat-less to careless downpipes.
LoL
Hello, I am faced with most likely replacing my catalytic converters on my 08 GTS with 128K miles. I have P0421 and P0431 codes. I already replaced all 4 O2 sensors, but the codes came back. So far, I've replaced thermostat, thermostat housing and updated the coolant lower pipe in the process as well. I've searched and ran out of other options on how to get rid of these codes. Do these codes mean front or rear cats? I'd appreciate any other suggestions or expertise anyone may have on this matter. If you could share some diy instructions on performing this task, thank you.
Not sure if this helps, but I chased the same problem. Kept getting codes....replaced O2 sensors...codes came back.
After noticing the codes would return more frequently when it was humid out, I started jiggling the wires where the O2 sensors plug in (in the engine bay) and sure enough, there was a loose wire in the plug that the O2 sensors plugs into. Simply jiggling the wires stopped the codes.
I recently replaced the coolant reservoir tank and in doing so, probably bumped the O2 sensor wires on the passenger side and low and behold, warnings came back. Reset them and they haven't returned. Those wires are touchy!!
Im talking about installing minincats on the post catalytic sencors.
Those are the once that throw CEL errors if your cats are bad or in this case missing.
Else if a tuner disables the sensors in the tune to keep the cell light away the car wont pass emissions test.
You seem to already have a good understanding of this, THE REAL QUESTION IS: Will the mini-cat spacers be efficient enough to keep the O2 sensors within the proper range to avoid triggering the CEL.
I am wondering the same thing, getting rid of primary cats should gain anywhere between 25-40 hp.
Obviously closer to the higher number with your Turbo.
Yes, to pass OBD2 emission test, no CEL errors allowed and all monitors must be “ready”, so disabling downstream O2 sensors via tune would not work for me too. In theory, mini cat spacers should do the trick, but real experience confirmation would be great.
My cats are throwing low efficiency codes as well, so just getting rid off them (as a punishment LOL), replacing with cat-less pipes would be awesome.
Finishing the job with installation of high flow cats in place of secondary cats would get rid of 70% of the smell.
If you ever proceed with the project, please post update.
Quick update. My engine needs to come out because it left coolant all over the highway. Im doing a ton of work while in there.
I ordered HH cat-less downpipes since both of my flex pipes are bad. also since engine is coming out, changing downpipes wont cost a thing.
Unfortunately Hank could not deliver and i canceled order. ordered FVD today. not as pretty and doesn't seem that they would flow as well as Hanks, but i have no other choice. Still catless, should be a good change in sound and a little HP.
Ordered Fabspeed mini cat spacers as well.
Will report when everything is done.
Quick update. My engine needs to come out because it left coolant all over the highway. Im doing a ton of work while in there.
I ordered HH cat-less downpipes since both of my flex pipes are bad. also since engine is coming out, changing downpipes wont cost a thing.
Unfortunately Hank could not deliver and i canceled order. ordered FVD today. not as pretty and doesn't seem that they would flow as well as Hanks, but i have no other choice. Still catless, should be a good change in sound and a little HP.
Ordered Fabspeed mini cat spacers as well.
Will report when everything is done.
Sorry forgot.
So Fabspeed mini catalytics did not fit no matter how the tech tried. The wires of the censor would have been rubbing on stuff. Ended up buying a couple different sets of small cheap mini cats and that worked through doubling up. Used a mini cat and then a small spacer with a small hole so not too much gas passes to the censor.
so use something like this on the censor itself:
and something like this in the actual exhaust pipe:
Please note YRMV. it is not guaranteed it will be enough for your sencors so you might have to try a combo of different things. I got all new sensors while i was at it jut to make sure everything is optimal.
The sound is slightly on raspy side at times for my taste but sound overall not too bad. good grunt when in sport mode and in comfort is almost not noticeable till you floor it. i prefer the cleanliness of the sound when in comfort but then it doesn't scream as loud
IMHO it has a little extra go. But on such heavy car nothing to write home about.....
Two years back, my 955 Turbo was not showing readiness on the CATS. Replaced the PCV diaphragm and the check valves between it and the intake. Ran some random cat cleaning stuff in a tank of gas. Passed SMOG inspection and stopped burning oil. Oil will coat and eventually kill cats. Clean cats should last a looooong time. An ounce of prevention is worth a pound of cure.
Two years back, my 955 Turbo was not showing readiness on the CATS. Replaced the PCV diaphragm and the check valves between it and the intake. Ran some random cat cleaning stuff in a tank of gas. Passed SMOG inspection and stopped burning oil. Oil will coat and eventually kill cats. Clean cats should last a looooong time. An ounce of prevention is worth a pound of cure.
Didn't do it because cats were bad. They were in perfect shape after 140k miles on the car. Both flex pipes were bad and engine was coming out anyway for other repairs. A set of FVDs were nearly same price as cutting and welding new flex pipes in.
Lucky for you. California is a PITA when it comes to CATs. Must be OEM or have a CARB approval # stamped into the body of the replacement cat. And CA approved replacement cats are way more expensive.
09-30-2019, 04:13 PM
