Testing for Blocked Catalytic Converter

[dsp26]

Hi All.

I have a suspicion my cat is blocked... the way my exhaust system is setup itś kinda hard to remove for me to wanna check visually so what i wanted to know is:
- Is it safe for me to drive the car around while the actual 02 sensor is unplugged from the bung? while the loom is still plugged in?

I just want to do a highway/motorway test at WOT and see if this frees up or reduces some hesitation as no one is willing to dyno my car with everything after the header removed.

[vinnY]

wouldn't your af ratios go all funny since it'll be reading next to no fuel?
drown the motor in petrol or something

[dsp26]

wouldn't your af ratios go all funny since it'll be reading next to no fuel?
drown the motor in petrol or something

was thinking that for when i drive normally to the motorway.. should be OK for WOT though right? closed loop ecu?

[bennjamin]

do not do it. o2 will read pure o2 instead of Carbon monoxide Sulphur Oxide
Nitrogen Oxide Br2O - and will dump as much fuel as it can to "counter" this apparent lean situation to protect the engine.

[dsp26]

damn. sorted then.

Just that the retards who flanged my cat at Bankstown had it slightly offset therefore has to be forced into a rotation slightly to get to align on one end... took me 2hrs to do 2 bolts last time...

mite just bring it to an exhaust shop then.

[dsp26]

ok just to revisit this, did some testing before getting my stomach operation...

turns out it is safe to unscrew O2 sensor as long as the engine hasn't warmed up fully....

cat is ****ed.. massive response difference.. would surely show up on the dyno.




my question is, why did my 4month old high flow metal core cat shit itself after my engine shat itself?

only thing i can think of is that i had a massive oil leak in the plug wells from worn rocker gasket and i was burning heaps of oil... crusted up, hardened and blocked in the catalyst?

[Limbo]

is it a metal cat? metal cats stuff up but their core does not usually break in pieces.
Hi-flow cats have a ceramic substance and they crack and block the pipes.

You should see the seams of all the exhaust joins start to carbon up or leak.

Last time this happened to me, it caused my header gasket to blow.

Good idea to take it to an exhaust shop and get it fixed. I get all my work dun at performance exhuast as you prob know, but since it 4 mths old i'd take it back.Take it down and get it fixed before it blows some of you other exhaust seals.

BTW... It might be a bad batch of cats. Dun tell me its a xforce one?

[dsp26]

^^^yeah just ordered a new one, but luckily i cannot drive for a month or so.... some things to help though with diagnosis which were my tell-tale signs and some specific to vtec:


- a completely clogged system will stall the car as the catalyst heats up and expands or prevent the car from revving past a certain point (those who have shoved steel wool in their exhaust for certain reasons will know what it feels like). mine ran ok from startup, but lost power as the car warmed up.

- a partially clogged system will dip the powerband significantly as rpms reach vtec x-over but start climbing again to a limit. This WILL NOT happen to non-vtec cars and will make the dyno sheet look like it's losing power in the midrange whereas on any other car powerloss is constant as rpm's rise. this is why i couldn't accept for the longest time that my cat was ****ed since it was only like 4months old

- the head, extractors, engine bay get hotter A LOT hotter than normal but not significant enough to be detected by the dash water temp gauge

- exhaust flow should be constant, when you rev the vehicle then back off suddenly there should still be outward flow on the muffler, even a partially blocked exhaust system will stop momentarily on throttle back off

- exhaust could smell like eggs (possibly a ceramic substrate thing), i had a metal cat, and in an underground carpark, smelled like very rich unburnt fuel possibly with water.

- ceramic cats have a high chance of shattering from rich mixtures resulting in 'exhaust pops' on throttle release

- metal cats generally have a higher temp threshhold but will melt when exceeded

- just because a cat is metal it is not indestructible or neccesarily 'high flow', especially if it has more than 200cpsi like mine did... mine had around 300cpsi (cells per square inch) making the gaps in the substrate narrower and more prone to melting and blockage.

- a true high flow cat will have 200cpsi or less (preferably 100cpsi) and be epa/carb approved because it uses heavier metal substrate to catalyse better to compensate for having less cells and less surface area to catalyse.

- easy test is to completely unscrew the primary o2 sensor or just test header back if your daring.

[CRXer]

hey ronny,still crxin i see?

no time,long see......

full of knowledge like always(i fell asleep halfway thru above post,ahhahaha)

u can run the O2 unbunged,just dont leave it hanging where it will burn something with the heater.Also just expect fuel usage to creep up at low loads(reset ecu when finished) or just take it for a quick run at high loads(open loop,o2 not active)

btw,is it blocked or did i miss that bit of info above?

[dsp26]

^^lol, was about to molest one of your other posts just to ask you the same... long time no see or hear friendage.

yeah twas partially blocked from melted catalyst in random chunks so dunno what caused it... since the substrate was so narrow i'm guessing some debree from when my engine blew flew into a read hot catalyst and melted bits together.

didn't wanna bother trying to undo the header back due to the weird bankstown exhaust job so wanted a partial confirmation by un-screwing the primary o2 sensor... the positive results from doing so was final confirmation that i needed to convince me to put the effort into actually removing the header back for visual check confirming blocked cat.

[CRXer]

dont molest me kind sir....im very fragile.............

did u run it long enough unbunged to run up a fuel system code or similar?

back to the strip now with new unbridled HP for u?

oh btw..............cat brand????

[dsp26]

dont molest me kind sir....im very fragile.............

did u run it long enough unbunged to run up a fuel system code or similar?

back to the strip now with new unbridled HP for u?

oh btw..............cat brand????

yeah as expected, when the car reached operating temp cel came on for o2 sensor.

one that was on the car was an american shipped metal cat... the new one on the way is an epa approved 2.5in 200cpsi metal cat from none other than magnaflow (AU$175 shipped from within Aussie btw)... i can't afford the exotic 100cpsi metalcat brand one :p

yeah once all fixed, gonna chuck my IM/TB back on and be back at the track

my lesson learned is...
brand stuff cheap on eBay = :thumbsup:
cheap non name eBay stuff = :thumbdwn::thumbdwn::thumbdwn::thumbdwn::thumbdwn: :thumbdwn::thumbdwn::thumbdwn::thumbdwn::thumbdwn: :thumbdwn::thumbdwn::thumbdwn:

[CRXer]

thought u learned eGay lesson long ago???

thats a good price man,i paid like $300 shipped for my metalcat,bout 3 years ago now,that was from aussie seller,wish i did bit more research.........

[dsp26]

^^what size? cheapest i found at 2.5 was $350 and that was on eGay for the metalcat brand

man you were away for a bit, did you see my thread on my 6puck xtr clutch shitting itself in traffic? another eGay lesson learned.... actually it was more of a realisation that i shouldn't believe everything i read on hondatech from so called experts and their cheap ways...

[bennjamin]

my last metalcat shat itself fairly quickly - about 15,000ks after install. The legacy lives on in my car ( big chunk rattling around in muffler). Now have a cheap XFORCE cat who knows who cares. Passes EPA thats all i can for :)

[CRXer]

my last metalcat shat itself fairly quickly - about 15,000ks after install. The legacy lives on in my car ( big chunk rattling around in muffler). Now have a cheap XFORCE cat who knows who cares. Passes EPA thats all i can for :)

yeh??..genuine metalcat or just metal-cat of some other brand??????

mines done 40k+ now,still workin

[dsp26]

yeah benny i'd be pretty pissed but the brand metalcat and magnaflow have warranty along the lines of 5yrs/50,000km from date of purchase

[CRXer]

^^what size? cheapest i found at 2.5 was $350 and that was on eGay for the metalcat brand

man you were away for a bit, did you see my thread on my 6puck xtr clutch shitting itself in traffic? another eGay lesson learned.... actually it was more of a realisation that i shouldn't believe everything i read on hondatech from so called experts and their cheap ways...

yeh,its 2.5,was from some vic company cant remember now,have to dig out my plethora of receipts to find.

hahaha.....6puck in sydney peak hour.....how painful......nowonder it shit itself.

oh ben,magical 14's maybe at wakey if u remove that chunk from ur arse pipe,yes u care.........yes u do

[bennjamin]

if anyone elses comments are to influence - removing the chunk out of my muffler would equate to low 13's at the 1/4 and 1.12 flat around wakie. Yeah. Rofl.It IS annoying tho.
BTW cat was stamped "catco" metalcat. So not an actual "metal cat" sorry to mislead you guys. Still - POS.

[CRXer]

if anyone elses comments are to influence - removing the chunk out of my muffler would equate to low 13's at the 1/4 and 1.12 flat around wakie. Yeah. Rofl.It IS annoying tho.
BTW cat was stamped "catco" metalcat. So not an actual "metal cat" sorry to mislead you guys. Still - POS.

maybe chunk is the only reason for 13.8's,1.15's.....who knows,could be magical chunk??????
its like fkd rear subframes could lead to 1.14's......who knows..............
go super stock man!!!!!!!!!!!......go!!!!!!!!!!!!

[bennjamin]

**** **** you are right. Magic chunk gives power. Magic subframe gives corner speed.

[dsp26]

^^^ if i get you gents correctly that only applies if you come from the right angle?

[CRXer]

^^^ if i get you gents correctly that only applies if you come from the right angle?

huh???? please explain.....im virgin........

it means ronny.....let car go to shit & magical things happen.........

see dude,ur trying too hard,just let it all go to pieces

[Limbo]

lol
i got a magnaflow metal cat also, its been pretty good.
They come in the standard cat shape which also helps keep the cops off your back.
usually when they see a metal cat they like to epa you