View Full Version : catalist removal ?

07-18-2004, 02:25 PM
going to have my cat's removed on my 1997 540i tomorow what kind of diffrence should i expect to see from her ? the engine has only done 28 k

07-18-2004, 02:30 PM
I dunno but wouldnt it mess up your emmissions from passing and possibly illegal. I think you should get some more power but not that much if doing a straight pipe.

maybe in uk you dont have emmissions testing but here in Canada its illegal to have no cat

07-18-2004, 02:42 PM
we only have emission testing here.

07-18-2004, 02:46 PM
no we have them aswell i know california has smog tests etc etc we have as part of our mot is a co2 emmisions test but the cats will be put back in for that

07-18-2004, 05:55 PM
Wont that throw you a Check Engine light??

07-18-2004, 05:57 PM
shouldnt do due to there not being any sensors there apart from the lamba/landa ???? but the exhaust gasses free flow past them thats what i think any way ?

07-18-2004, 06:28 PM
Emissions this Emissions that.... just got to a Russian garage pay them 200 and there you go you passed :\.....

07-18-2004, 09:43 PM
....LOL .... imagine sitting in the traffic jam and looking back on your rear view mirror and wondering why are those people behind your car falling to sleep in the car .....lol...

07-18-2004, 09:47 PM
Originally posted by 535isport
going to have my cat's removed on my 1997 540i tomorow what kind of diffrence should i expect to see from her ? the engine has only done 28 k

no performance value....louder though

07-18-2004, 10:18 PM
wow only 28k on a 97

i thought mine was low, just hit 35 on a 98

damn that car must sit a lot

07-18-2004, 10:24 PM
shouldnt there be a small performance value? basically its free flowing and nothing to slow down the escaping gasses?

I think you get like a 20 horsepower gain probably more

but a) its LOUD as ****.
and wouldn;t you be able to blow fire out of the exhaust pipe?maybe not cuz the exhaust pipe is too long?

07-18-2004, 10:26 PM
you won't gain 20hp, maybe 5hp, it will be louder, & because the cats are removed you would love some backpressure causing backfire at high RPM's

07-19-2004, 06:29 AM
i love the siting in trafic coment sounds good ill just give it a rev if people geton my nervs lol not fussed about beformance realy as long as it sorts my miss fire out fingers crossed as for it being louder its a v8 you can never have it to loude lol

07-19-2004, 09:48 AM
Originally posted by 535isport
shouldnt do due to there not being any sensors there apart from the lamba/landa ???? but the exhaust gasses free flow past them thats what i think any way ?

If its an OBD II ecu then it probably will throw a check engine light, because they have 2 O2 sensors one before the CAT and one after, the one after is to make sure that the cat is doing its job, if the ecu gets the same reading off both the sensors it will assume the cat is no longer working and will set the light off.

07-19-2004, 06:56 PM
Bad idea in my opinion!!! *no-no*

First of all, it's illegal and you'll be polluting the environment for extremely minor performance gains. Second, you'll be loosing some needed backpressure from your engine, therefore loosing a lot of low-end torque at low RPM's. Unless you plan on staying past 5000 RPM, you're wasting your time and the environment.

07-19-2004, 06:59 PM
had it done today cat's out its brilliant berfomance brilliant noise took it straight to 140 like it wasnt evan trying im so happy and no it didnt come up with a check engine light which is evan better

07-19-2004, 07:05 PM
Just because it's louder does not mean that it's faster. Perception is not reality. :rolleyes:

07-19-2004, 07:06 PM
em missing my point i know what you mean but when the cats where on there and the car was missing now all the time on cylinder 1-9 it is about twice as fast as it was !

07-19-2004, 07:19 PM
OK now I'm confused, your car was missing on 9 cylinders??? I'll assume you meant 8 cylinders, but in any event, if your engine was missing, especially all 8 cylinders are a car with only 28k miles, you have serious problems other than your catalysts, unless they were clogged beyond belief.. which I seriously doubt at 28k miles. Also, if your engine was missing, you would have had a check engine light, in addition, OBD-II would have triggered the check engine light to blink indicating a major engine problem.

I don't disagree that your engine sounds good, but if nice sound was your goal, you could have accomplished the same by installing a free-flowing catback exhaust system. At least that way, you would not be contributing to major air pollution.

For what it's worth...

- Surge

07-19-2004, 07:24 PM
i may have miss typed one of my posts yes i ment 8 cylinders the ENGINE has done 28k sinse it was replaced at 98k when the old engine sucked alot of water up and put a piston thru the block the car it self has done 118k hence why it needed removeing and it doesnt have the second set of sensors soit didnt trigger the check engine light , as to the comment about my pollution compar me to the 00000000's of people running around in there death traps with out mot's and smog tests etc ect and evan worse massive companys filling our air with god knows what polution mine is very little cheers

07-19-2004, 07:42 PM
I replaced my cats because they were clogged causing severe missfire, my car would stall out and limit my speed as well

07-19-2004, 08:02 PM
Well... what can I say? If you're not part of the solution, you're part of the problem. I guess I take environmental issues quite seriously, but then again, since I own a car I'm also part of the problem - so I'm guilty as well.

07-20-2004, 04:43 AM
QUACK = that is the exact same thing mine was doing but when i first got it i didnt notice it (my dad did thought staraight away ) lol but the other owner knew aswell but at a price of 1100 to replace the cat's from bmw he s##t him self but i just got them removed for £175