Ran a while with a broken MAF on my car...

Ran a while with a broken MAF on my car, the catalytic converters were already reaching their limit and now I am sure they are toasted.
Anyone could share their stories about removing the CATS. ?
Thanks!

the oil blowback in my SLK fouls my maf too,but i just clean it every half year and it's going strong. How could you leave it long enough for it to die?

Also if yours is like my SLK I had dual cats, Which i had removed and replaced with 1 large high flow cat. The entire exhaust was replaced though.

Had a BMW E39 530i, removed the Y-resonator and the rear muffler to get some sound going, since it was almost completely silent when stock, sounded really good without being loud or obnoxious in any way.

Then the cats shit themselves, removed them and it was so fucking obnoxiously loud you could literally hear it screaming half a city away. Was fun at times, but it got pretty tiring over time and just cruising in it was too loud to be comfy for daily driving, but probably wouldn't be if the mufflers were still in its place.

If I remember right the supercharger on those mercades usually burn them selves and other parts out. And buying cats for the kompressor version might be a little pricey if they really broke.
You can't really run a merc with a busted sensor cause the whole car detect it and some other part will stop working. If anything DONT go to a dealership find a small certified Merc auto shop

If it doesn't throw cat efficiency codes just ignore it.

As for replacing cats? Well, like most exhaust work, it's a fun time torching the nuts and bolts glowing red hot to try to break them loose. Don't reuse the old nuts, bolts, and gaskets. Do use high temp never-seize imo (that's just like my opinion maaan). And hopefully you won't have to start cutting things apart with a sawzall, replacing more than you thought you'd have to due to rotted out flanges, or draging it to a shop with your tail between your legs because you rounded something off and admitted defeat.

Had to travel 1000km non stop. The MAF cel came up and Im pretty sure it read the mixture only on the upstream O2 sensor as the car was dying at idle.
I didnt had the choice.
Fixed the MAF at home and since then it is rattling like crazy near the two cats..

Good, thanks! I really like the M111, an amazing engine. I though about bypassing both cats even if it throws me a CEL, its my summer car anyway.

I read about that, right now it is Manifold -> flex pipe -> two cats in tandem -> resonator -> muffler.
Dont plan to touch the resonator nor the muffler, just the cats.

Thanks for your input!

Well, I always thought the Downstream sensor was useless in a modern OBD2 sensor. It only indicate the ECU if the cats do their jobs while the Upstream is essential for fuel/air mixture.
I have to be honest I never ran with no cats so we will see.
If they are clogged I hope I will see a difference.

Haha, you are not wrong it is a bit rusted. I already dissasemble the manifold/flexpipe flange.
The rest is just two rubber hooks and two bolts (soaking in penetratiing oil right now). Will get the whole thing off to.work on it.

Well, it is rattling like crazy and the way it is made it looks like if one cat is clogged the other take all the load.
Anyway this is a summer car and I didnt paid a lot for it so, why not try it.

It's possible you might have overheated the cat to the point where the catalyst matrix came detached or started to break apart (age would help do this anyway). You if take the cat off and it's a maraca then that's what happened. It might or might not still be in good enough shape to do its job. Or pieces could start blowing out the back, facing the wrong direction, and otherwise clogging up the exhaust.

Sometimes you can tell that this is the case just by tapping on the cat to find out which one has loose stuff knocking around inside.

Yeah in the E39 the cats are in the exhaust manifold, getting to them is a bitch, and new cats would've been around 1400$, got equal length headers for 400$ and put those in instead. Car won't pass inspection this year though if the guy checks the emissions, but many people here in Iceland get off with minor stuff like that

The whole idea of them using two sets of o2 sensors is kind of dumb and costly, I get it can pick up better readings but it also just complicates everything especially if you don't have a mercades diagnosis tool/computer.
It might run a bit richer but not as much as an american car with a busted or clogged cat

Do they have an actual wideband or actual A/F in the rear? For what purpose, some fraction of a percent improvement in fuel efficiency?

Car is 18 years old with 230 000KM.
Pretty sure what I did killed the already aging cats.
I will check tonight if it rattles inside. Thanks!

We don't have yearly inspection in here so I will be good. The only reason why I would be in trouble is a LOUD exhaust system then the cops gives you a mandatory inspection.

I don't think it will sound like hell once I take off the cats because there will still be the resonator and the muffler.

>I always thought the Downstream sensor was useless in a modern OBD2 sensor. It only indicate the ECU if the cats do their jobs while the Upstream is essential for fuel/air mixture.

this has been my understanding as well, user

i'm gonna call 'citation required' on the idea that downstream O2s are being used to trim fuel mixture.

oxygen content after catalytic processing is not valuable to determine engine emissions, because the variable of "how effective are the cats" is not known and can't be predicted.

I've had bad downstream sensors on two cars and it didnt affected anything.
We will see with this one!

Yeah if the rest is stock you should probably be fine, my E39 went mainfold/cats->big middle muffler->Y-resonator->rear muffler, since i removed the Y resonator and rear muffler, when i replaced the cats, the only "muffler" of the 4 original ones was the long one in the middle, so 1/4 of the sound deading was gone, otherwise it probably would've been fine.

Weird thing is that in all the time i had this car, over a year, half the time it being obnoxiously loud, i was only pulled over once, and that was because i didn't have a front plate, which went on for 3 weeks without me being pulled over, even though i was passing and seeins cops allt he time.

Car was all black, with illegal tint in the front (no tint is allowed), ridiculously loud, always hooning, and i pretty much always had the front fogs on and the headlights off, yet i was never pulled over, cops here are weird man

>pic related

Both sensors on my W202 have 4 wires.
I think the newer sensors runs on 5 wires, probably mean it is a wideband sensor.
I could be wrong tough.

Sweet bimmer! A pure cops magnet in here loll.
I don't want any ,"drone" noise either. Anyway a loud exhaust system with an automatic transmission is pointless

Thanks! Sold it a few months back though, maintenance kept biting me in the ass, but it was a great, really fun car, handled like it was on rails (M-Sport suspension with lowering springs)

When i had the muffler and Y-resonator removed, there was a slight drone at certain RPMs but i got used to it really fast and it didn't bother me, after i removed the cats however it was always almost unbearably loud.

That probably differs between cars though, some cars become unbearable just by removing the muffler while other cars are fine after you remove a shitload of stuff from the exhaust, but if the whole exhaust is stock and you just remove the mufflers, i don't think it should be too bad in any decent car

The more I read the less I think the downstream sensor doesnt influence the A/F mix.
I fear the car will be stuck in open loop. (Not good).

Nevermind. I'll cut these bastards off.