Catalytic converters?? What to do??

[rudutoit]

Hi guys!

I had a little issue with my car the other day, it started feeling sluggish and after sitting in traffic for two hours (DAMN the N12!!!) my engine management light came on and the car was dead! (I wouldn't rev beyond 3000 rpm)

After getting home I put it on a x-431 diagnostic computer and it came up with all sorts of funny errors about fueling and environmental warnings, but basically my cats are shot!

Has anyone replaced cats on a BMW? I don't want to spend the 22k at the dealers.

I am thinking I want to put small canister mufflers on where they are at the moment but I think I am going to get fault codes because I have 4 o2 Sensors like this:

If anyone has any advise I will appreciate it!

Thanks!

 

[Sherwin@xcede]

Drill them out.

 

[SirSparky]

well this is my experiance with cats.........

with all my cars where i have removed the cats i have replaced them with a free flow box.sometimes you will get the engine light still coming on because the readings on the o2 sensors are still incorrect according to the ecu specs.
inorder for this to go away you need to get something thats called a cat fooler.

last time i got a price which was about 1 year ago from stingray exhausts in jhb was R450 per fooler.so if you have 2 02 sensors youre gonna need 2 foolers.....

the boxes should cost you between 700-1000 per box....depending on where you get them...still a whole lot cheaper than what bmw are asking!

 

[plonkster]

I saw an interesting invention at Hex microsystems ones (hex.co.za), a little black box that pretends to be a lambda sensor and simply gives a constant healthy reading. I'm pretty sure this will have all sorts of performance affecting side-effects, but it should allow you to remove the cats completely and just feed the ECU with a signal saying all is fine. Yes, it is a little evil.

 

[SirSparky]

if you still wanna maintain the orig cats i could prob find out for you from my contact in the states how much its gonna cost to replace the cats....imho......get the free flow boxes.....those cats will eventually block again due to our poor quality fuel

 

[rudutoit]

I have two freeflow boxes that I can stick in the system. As I understand it the back O2 sensors are just there to annoy you when your cats go bad... All the tuning and ECU values are handled by the front O2 Sensors??

Thanks for the help guys, I am going to do this today so I'll have feedback later... I am not doing the foolers or anything on the back yet because I need the car running again ASAP. If I need the foolers I will do them next week...

Cheers!

 

[SirSparky]

the car will still perform badly if the foolers are not in.you might be lucky and the ecu wont need them.

 

[clutchplate]

hmm, interesting. I'd just remove the cats completely will make it sound better too, and bit more performance ...

btw, are you sure about only the front sensors being used by the ECU for tuning ? and the back sensors are ONLY used to test if the CATS are faulty ? do the rear 2 sensors change ecu tuning also ? ...

because my rear two sensors I think are FRIED...

 

[SirSparky]

the rear ones according to the guys in the state are basically just to let you know if ur cats are fried...the pre 02 senors do the fueling etc

 

[ANiMOSiTY]

Front/Primary/Pre-Cat O2 Sensors are directly used for fuel mixture control, in conjunction with the MAFs.
The Rear/Secondary/Post-Cat O2 Sensors are primarily there to monitor Catalytic Converter performance but DO affect long-term fuel trimming.

Biofreak did a de-cat on his M5, and simply replaced the cats with straight pipes - no ECU/CEL lights at all.

 

[SirSparky]

did he get any dme codes stored or not?

 

[ANiMOSiTY]

did he get any dme codes stored or not?

I don't think so, but even if the DME did log some codes, it's not serious enough to pull timing or power, so I wouldn't worry about it.

That's his car though.. Your results may vary.

 

[SirSparky]

i believe your cps was giving problems thats why your L/H reading was low.....did your car battle to start at all with this?

 

[danielscvhamann]

I would also just remove them, save your self the money, and you even get some more performance out of it as well.

You can have a problem with fault codes and engine light coming on but you can avoid that easily with an ECU upgrade for example then the problem is gone or one of those foolers as mentioned above...

 

[clutchplate]

Rudutoit, your lights won't come on. all 4 my cats are removed... we did detect the 2 rear o2 sensors with BimmerMan's Carsoft. but I think its just that both my rear sensors are acctually toasted, because we struggled to get them out when we were making my exhaust...

ok, I'm glad it doesn't REALLY affect the fueling/performance. hmm. I'm contemplating going stand alone ECU on beemer sometime. dunno tho. Would love to find a way to program the ecu thats in there directly.

 

[ANiMOSiTY]

i believe your cps was giving problems thats why your L/H reading was low.....did your car battle to start at all with this?

You talking to me, or the original poster?
Wrong thread

 

[rudutoit]

i believe your cps was giving problems thats why your L/H reading was low.....did your car battle to start at all with this?

You talking to me, or the original poster?
Wrong thread

My car started acting up Wednesday... It gets better and then freaks out again... As soon as I drive on the highway or get stuck in traffic...

I think the cats are heating up and choking my engine... I am only going to be able to sort it out on monday

 

[SirSparky]

ani u have pm